Donnelly-Roberts D

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Full name : Donnelly-Roberts Diana L

First name : Diana L

Mail : Neuroscience Research, Global Pharmaceutical Research and Development, Abbott Laboratories, 100 Abbott Park Road, Abbott Park, IL 60064-6100

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Country : USA

Email : diana.l.donnelly-roberts@abbvie.com

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References (74)

Title : Reducing inflammation and rescuing FTD-related behavioral deficits in progranulin-deficient mice with alpha7 nicotinic acetylcholine receptor agonists - Minami_2015_Biochem.Pharmacol_97(4)_454
Author(s) : Minami SS , Shen V , Le D , Krabbe G , Asgarov R , Perez-Celajes L , Lee CH , Li J , Donnelly-Roberts D , Gan L
Ref : Biochemical Pharmacology , 97 :454 , 2015
Abstract : Mutations in the progranulin gene cause frontotemporal dementia (FTD), a debilitating neurodegenerative disease that involves atrophy of the frontal and temporal lobes and affects personality, behavior, and language. Progranulin-deficient mouse models of FTD exhibit deficits in compulsive and social behaviors reminiscent of patients with FTD, and develop excessive microgliosis and increased release of inflammatory cytokines. Activation of nicotinic acetylcholine receptors (nAChRs) by nicotine or specific alpha7 nAChR agonists reduces neuroinflammation. Here, we investigated whether activation of nAChRs by nicotine or alpha7 agonists improved the excessive inflammatory and behavioral phenotypes of a progranulin-deficient FTD mouse model. We found that treatment with selective alpha7 agonists, PHA-568487 or ABT-107, strongly suppressed the activation of NF-kappaB in progranulin-deficient cells. Treatment with ABT-107 also reduced microgliosis, decreased TNFalpha levels, and reduced compulsive behavior in progranulin-deficient mice. Collectively, these data suggest that targeting activation of the alpha7 nAChR pathway may be beneficial in decreasing neuroinflammation and reversing some of the behavioral deficits observed in progranulin-deficient FTD.
ESTHER : Minami_2015_Biochem.Pharmacol_97(4)_454
PubMedSearch : Minami_2015_Biochem.Pharmacol_97(4)_454
PubMedID: 26206194

Title : Nicotinic acetylcholine receptors as therapeutic targets: Emerging frontiers in basic research and clinical science--Editorial Comments -
Author(s) : Dani JA , Donnelly-Roberts D , Bertrand D
Ref : Biochemical Pharmacology , 97 :351 , 2015
PubMedID: 26074266

Title : Nicotinic acetylcholine receptors as therapeutic targets: emerging frontiers in basic research and clinical science--editorial comments -
Author(s) : Dani JA , Donnelly-Roberts D , Bertrand D
Ref : Biochemical Pharmacology , 86 :1041 , 2013
PubMedID: 23684691

Title : Synthesis and SAR of 4-aminocyclopentapyrrolidines as N-type Ca(2)(+) channel blockers with analgesic activity - Beebe_2012_Bioorg.Med.Chem_20_4128
Author(s) : Beebe X , Darczak D , Henry RF , Vortherms T , Janis R , Namovic M , Donnelly-Roberts D , Kage KL , Surowy C , Milicic I , Niforatos W , Swensen A , Marsh KC , Wetter JM , Franklin P , Baker S , Zhong C , Simler G , Gomez E , Boyce-Rustay JM , Zhu CZ , Stewart AO , Jarvis MF , Scott VE
Ref : Bioorganic & Medicinal Chemistry , 20 :4128 , 2012
Abstract : A novel 4-aminocyclopentapyrrolidine series of N-type Ca(2+) channel blockers have been discovered. Enantioselective synthesis of the 4-aminocyclopentapyrrolidines was enabled using N-tert-butyl sulfinamide chemistry. SAR studies demonstrate selectivity over L-type Ca(2+) channels. N-type Ca(2+) channel blockade was confirmed using electrophysiological recording techniques. Compound 25 is an N-type Ca(2+) channel blocker that produces antinociception in inflammatory and nociceptive pain models without exhibiting cardiovascular or motor liabilities.
ESTHER : Beebe_2012_Bioorg.Med.Chem_20_4128
PubMedSearch : Beebe_2012_Bioorg.Med.Chem_20_4128
PubMedID: 22626552

Title : High throughput functional assays for P2X receptors - Namovic_2012_Curr.Protoc.Pharmacol_Chapter 9_Unit 9 15
Author(s) : Namovic MT , Jarvis MF , Donnelly-Roberts D
Ref : Curr Protoc Pharmacol , Chapter 9 :Unit 9 15 , 2012
Abstract : Adenosine triphosphate (ATP) activates two receptor superfamilies, metabotropic P2Y and ionotropic P2X receptors. The P2X receptors are nonselective cation channels that are widely expressed on excitable cells including neurons, glia, and smooth muscle cells. The protocols in this unit are useful for evaluating ligands that interact with P2X receptors on native cells or that are cloned and expressed in recombinant heterologous cell systems. Calcium imaging methods are described for the pharmacological characterization of fast or slowly desensitizing P2X receptors. While these methods are readily applicable to a wide variety of ligand-gated ion channels, the protocols provided herein detail how they can be used to measure activation of homomeric P2X3 (fast desensitizing) and heteromeric P2X2/3 (slowly desensitizing) receptors. Appropriate agonists and/or calcium dyes can be substituted to assess activity at other P2X receptor subtypes. An additional protocol is provided for measuring P2X7 receptor-mediated pore formation in THP-1, a native human acute monocytic leukemia cell line that can be used to study homomeric P2X7 (non-desensitizing) receptors that are expressed on macrophages and microglial cells.
ESTHER : Namovic_2012_Curr.Protoc.Pharmacol_Chapter 9_Unit 9 15
PubMedSearch : Namovic_2012_Curr.Protoc.Pharmacol_Chapter 9_Unit 9 15
PubMedID: 22684723

Title : Comparative analysis of inactivated-state block of N-type (Ca(v)2.2) calcium channels - Vortherms_2011_Inflamm.Res_60_683
Author(s) : Vortherms TA , Swensen AM , Niforatos W , Limberis JT , Neelands TR , Janis RS , Thimmapaya R , Donnelly-Roberts D , Namovic MT , Zhang D , Brent Putman C , Martin RL , Surowy CS , Jarvis MF , Scott VE
Ref : Inflamm Res , 60 :683 , 2011
Abstract : OBJECTIVE: The aim of this study was to compare a diverse set of peptide and small-molecule calcium channel blockers for inactivated-state block of native and recombinant N-type calcium channels using fluorescence-based and automated patch-clamp electrophysiology assays.
METHODS: The pharmacology of calcium channel blockers was determined at N-type channels in IMR-32 cells and in HEK cells overexpressing the inward rectifying K(+) channel Kir2.1. N-type channels were opened by increasing extracellular KCl. In the Kir2.1/N-type cell line the membrane potential could be modulated by adjusting the extracellular KCl, allowing determination of resting and inactivated-state block of N-type calcium channels. The potency and degree of state-dependent inhibition of these blockers were also determined by automated patch-clamp electrophysiology.
RESULTS: N-type-mediated calcium influx in IMR-32 cells was determined for a panel of blockers with IC(50) values of 0.001-7 muM and this positively correlated with inactivated-state block of recombinant channels measured using electrophysiology. The potency of several compounds was markedly weaker in the state-dependent fluorescence-based assay compared to the electrophysiology assay, although the degree of state-dependent blockade was comparable.
CONCLUSIONS: The present data demonstrate that fluorescence-based assays are suitable for assessing the ability of blockers to selectively interact with the inactivated state of the N-type channel.
ESTHER : Vortherms_2011_Inflamm.Res_60_683
PubMedSearch : Vortherms_2011_Inflamm.Res_60_683
PubMedID: 21394563

Title : Nicotinic acetylcholine receptors as therapeutic targets: emerging frontiers in basic research and clinical science--Editorial Comments -
Author(s) : Donnelly-Roberts D , Bertrand D , Gopalakrishnan M
Ref : Biochemical Pharmacology , 82 :797 , 2011
PubMedID: 21600889

Title : Poster: A-582941, a pro-cognitive alpha7 nAChR agonist, differentially modulates mitochondrial membrane potential -
Author(s) : Namovic M , Hu M , Abraham V , Towne D , Lee C-H , Gopalakrishnan M , Esbenshade T , Donnelly-Roberts D
Ref : Biochemical Pharmacology , 82 :1027 , 2011
PubMedID:

Title : Synthesis and in vitro activity of N-benzyl-1-(2,3-dichlorophenyl)-1H-tetrazol-5-amine P2X(7) antagonists - Perez-Medrano_2011_Bioorg.Med.Chem.Lett_21_3297
Author(s) : Perez-Medrano A , Donnelly-Roberts D , Florjancic AS , Nelson DW , Li T , Namovic MT , Peddi S , Faltynek CR , Jarvis MF , Carroll WA
Ref : Bioorganic & Medicinal Chemistry Lett , 21 :3297 , 2011
Abstract : Synthesis and biological evaluation of a novel class of substituted N-benzyl-1-(2,3-dichlorophenyl)-1H-tetrazol-5-amine derivatives resulted in the identification of potent P2X(7) antagonists. These compounds were assayed for activity at both the human and rat P2X(7) receptors. On the benzyl moiety, a variety of functional groups were tolerated, including both electron-withdrawing and electron-donating substituents. Ortho-substitution on the benzyl group provided the greatest potency. The ortho-substituted analogs showed approximately 2.5-fold greater potency at human compared to rat P2X(7) receptors. Compounds 12 and 38 displayed hP2X(7)pIC(50)s>7.8 with less than 2-fold difference in potency at the rP2X(7).
ESTHER : Perez-Medrano_2011_Bioorg.Med.Chem.Lett_21_3297
PubMedSearch : Perez-Medrano_2011_Bioorg.Med.Chem.Lett_21_3297
PubMedID: 21536435

Title : Discovery and biological evaluation of novel cyanoguanidine P2X(7) antagonists with analgesic activity in a rat model of neuropathic pain - Perez-Medrano_2009_J.Med.Chem_52_3366
Author(s) : Perez-Medrano A , Donnelly-Roberts D , Honore P , Hsieh GC , Namovic MT , Peddi S , Shuai Q , Wang Y , Faltynek CR , Jarvis MF , Carroll WA
Ref : Journal of Medicinal Chemistry , 52 :3366 , 2009
Abstract : We disclose the design of a novel series of cyanoguanidines that are potent (IC(50) approximately 10-100 nM) and selective (> or = 100-fold) P2X(7) receptor antagonists against the other P2 receptor subtypes such as the P2Y(2), P2X(4), and P2X(3). We also found that these P2X(7) antagonists effectively reduced nociception in a rat model of neuropathic pain (Chung model). Particularly, analogue 53 proved to be effective in the Chung model, with an ED(50) of 38 micromol/kg after intraperitoneal administration. In addition compound 53 exhibited antiallodynic effects following oral administration and maintained its efficacy following repeated administration in the Chung model. These results suggest an important role of P2X(7) receptors in neuropathic pain and therefore a potential use of P2X(7) antagonists as novel therapeutic tools for the treatment of this type of pain.
ESTHER : Perez-Medrano_2009_J.Med.Chem_52_3366
PubMedSearch : Perez-Medrano_2009_J.Med.Chem_52_3366
PubMedID: 19397270

Title : The antihyperalgesic activity of a selective P2X7 receptor antagonist, A-839977, is lost in IL-1alphabeta knockout mice - Honore_2009_Behav.Brain.Res_204_77
Author(s) : Honore P , Donnelly-Roberts D , Namovic M , Zhong C , Wade C , Chandran P , Zhu C , Carroll W , Perez-Medrano A , Iwakura Y , Jarvis MF
Ref : Behavioural Brain Research , 204 :77 , 2009
Abstract : The pro-inflammatory cytokine interleukin-1beta (IL-1beta) has been implicated in both inflammatory processes and nociceptive neurotransmission. Activation of P2X7 receptors is the mechanism by which ATP stimulates the rapid maturation and release of IL-1beta from macrophages and microglial cells. Recently, selective P2X7 receptor antagonists have been shown to reduce inflammatory and neuropathic pain in animal models. However, the mechanisms underlying these analgesic effects are unknown. The present studies characterize the pharmacology and antinociceptive effects of a structurally novel P2X7 antagonist. A-839977 potently (IC50=20-150 nM) blocked BzATP-evoked calcium influx at recombinant human, rat and mouse P2X7 receptors. A-839977 also potently blocked agonist-evoked YO-PRO uptake and IL-1beta release from differentiated human THP-1 cells. Systemic administration of A-839977 dose-dependently reduced thermal hyperalgesia produced by intraplantar administration of complete Freund's adjuvant (CFA) (ED50=100 micromol/kg, i.p.) in rats. A-839977 also produced robust antihyperalgesia in the CFA model of inflammatory pain in wild-type mice (ED50=40 micromol/kg, i.p.), but the antihyperalgesic effects of A-839977 were completely absent in IL-1alphabeta knockout mice. These data demonstrate that selective blockade of P2X7 receptors in vivo produces significant antinociception in animal models of inflammatory pain and suggest that the antihyperalgesic effects of P2X7 receptor blockade in an inflammatory pain model in mice are mediated by blocking the release of IL-1beta.
ESTHER : Honore_2009_Behav.Brain.Res_204_77
PubMedSearch : Honore_2009_Behav.Brain.Res_204_77
PubMedID: 19464323

Title : Nicotinic acetylcholine receptors as therapeutic targets: emerging frontiers in basic research and clinical science--editorial perspective -
Author(s) : Bertrand D , Gopalakrishnan M , Donnelly-Roberts D
Ref : Biochemical Pharmacology , 78 :657 , 2009
PubMedID: 19576180

Title : Selective P2X(7) receptor antagonists for chronic inflammation and pain - Carroll_2009_Purinergic.Signal_5_63
Author(s) : Carroll WA , Donnelly-Roberts D , Jarvis MF
Ref : Purinergic Signal , 5 :63 , 2009
Abstract : ATP, acting on P2X(7) receptors, stimulates changes in intracellular calcium concentrations, maturation, and release of interleukin-1beta (IL-1beta), and following prolonged agonist exposure, cell death. The functional effects of P2X(7) receptor activation facilitate several proinflammatory processes associated with arthritis. Within the nervous system, these proinflammatory processes may also contribute to the development and maintenance of chronic pain. Emerging data from genetic knockout studies have indicated specific roles for P2X(7) receptors in inflammatory and neuropathic pain states. The discovery of multiple distinct chemical series of potent and highly selective P2X(7) receptor antagonists have enhanced our understanding of P2X(7) receptor pharmacology and the diverse array of P2X(7) receptor signaling mechanisms. These antagonists have provided mechanistic insight into the role(s) P2X(7) receptors play under pathophysiological conditions. In this review, we integrate the recent discoveries of novel P2X(7) receptor-selective antagonists with a brief update on P2X(7) receptor pharmacology and its therapeutic potential.
ESTHER : Carroll_2009_Purinergic.Signal_5_63
PubMedSearch : Carroll_2009_Purinergic.Signal_5_63
PubMedID: 18568426

Title : Poster: Radioligand binding characterization of [3H]-A-998679: A novel positive allosteric modulator of alpha4\/beta2 nAChRs -
Author(s) : Anderson DJ , Vaidyanathan S , Namovic M , Donnelly-Roberts D , Lee L , Gopalakrishnan M
Ref : Biochemical Pharmacology , 78 :903 , 2009
PubMedID:

Title : Poster: Profile of A-716096, a novel thiazolylidine positive allosteric modulator of the alpha7 nicotinic acetylcholine receptor -
Author(s) : Donnelly-Roberts D , Malysz J , Faghih R , Gronlien H , Haakerud M , Thorin-Hagne K , Ween H , Gopalakrishnan SM , Hu M , Li J , Anderson DJ , Kohlhaas KL , Namovic M , Radek R , Robb H , Briggs CA , Bitner RS , Bunnelle WH , Gopalakrishnan M
Ref : Biochemical Pharmacology , 78 :912 , 2009
PubMedID:

Title : Mammalian P2X7 receptor pharmacology: comparison of recombinant mouse, rat and human P2X7 receptors - Donnelly-Roberts_2009_Br.J.Pharmacol_157_1203
Author(s) : Donnelly-Roberts D , Namovic MT , Han P , Jarvis MF
Ref : British Journal of Pharmacology , 157 :1203 , 2009
Abstract : BACKGROUND AND PURPOSE: Acute activation of P2X7 receptors rapidly opens a non-selective cation channel. Sustained P2X7 receptor activation leads to the formation of cytolytic pores, mediated by downstream recruitment of hemichannels to the cell surface. Species- and single-nucleotide polymorphism-mediated differences in P2X7 receptor activation have been reported that complicate understanding of the physiological role of P2X7 receptors. Studies were conducted to determine pharmacological differences between human, rat and mouse P2X7 receptors. EXPERIMENTAL APPROACH: Receptor-mediated changes in calcium influx and Yo-Pro uptake were compared between recombinant mouse, rat and human P2X7 receptors. For mouse P2X7 receptors, wild-type (BALB/c) and a reported loss of function (C57BL/6) P2X7 receptor were also compared. Key results: BzATP [2,3-O-(4-benzoylbenzoyl)-ATP] was more potent than ATP in stimulating calcium influx and Yo-Pro uptake at rat, human, BALB/c and C57BL/6 mouse P2X7 receptors. Two selective P2X7 receptor antagonists, A-740003 and A-438079, potently blocked P2X7 receptor activation across mammalian species. Several reported P2X1 receptor antagonists [e.g. MRS 2159 (4-[(4-formyl-5-hydroxy-6-methyl-3-[(phosphonooxy)methyl}-2-pyridinyl)azo]-benzoi c acid), PPNDS and NF279] blocked P2X7 receptors. NF279 fully blocked human P2X7 receptors, but only partially blocked BALB/c P2X7 receptors and was inactive at C57BL/6 P2X7 receptors. CONCLUSIONS AND IMPLICATIONS: These data provide new insights into P2X7 receptor antagonist pharmacology across mammalian species. P2X7 receptor pharmacology in a widely used knockout background mouse strain (C57BL/6) was similar to wild-type mouse P2X7 receptors. Several structurally novel, selective and competitive P2X7 receptor antagonists show less species differences compared with earlier non-selective antagonists.
ESTHER : Donnelly-Roberts_2009_Br.J.Pharmacol_157_1203
PubMedSearch : Donnelly-Roberts_2009_Br.J.Pharmacol_157_1203
PubMedID: 19558545

Title : [3H]A-804598 ([3H]2-cyano-1-[(1S)-1-phenylethyl]-3-quinolin-5-ylguanidine) is a novel, potent, and selective antagonist radioligand for P2X7 receptors - Donnelly-Roberts_2009_Neuropharmacol_56_223
Author(s) : Donnelly-Roberts D , Namovic MT , Surber B , Vaidyanathan SX , Perez-Medrano A , Wang Y , Carroll WA , Jarvis MF
Ref : Neuropharmacology , 56 :223 , 2009
Abstract : ATP-sensitive P2X7 receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X7 receptors leads to rapid changes in intracellular calcium concentrations, release of the pro-inflammatory cytokine IL-1beta, and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Data from gene knockout studies and recently described selective antagonists indicate a role for P2X7 receptor activation in inflammation and pain. While several species selective P2X7 antagonists exist, A-804598 represents a structurally novel, competitive, and selective antagonist that has equivalent high affinity at rat (IC50 = 10 nM), mouse (IC50 = 9 nM) and human (IC50 = 11 nM) P2X7 receptors. A-804598 also potently blocked agonist stimulated release of IL-1beta and Yo-Pro uptake from differentiated THP-1 cells that natively express human P2X7 receptors. A-804598 was tritiated ([3H]A-804598; 8.1Ci/mmol) and utilized to study recombinant rat P2X7 receptors expressed in 1321N1 cells. [3H]A-804598 labeled a single class of high affinity binding sites (Kd=2.4 nM and apparent Bmax=0.56 pmol/mg). No specific binding was observed in untransfected 1321N1 cells. The pharmacological profile for P2X antagonists to inhibit [3H]A-804598 binding correlated with their ability to block functional activation of P2X7 receptors (r=0.95, P<0.05). These data demonstrate that A-804598 is one of the most potent and selective antagonists for mammalian P2X7 receptors described to date and [3H]A-804598 is a high affinity antagonist radioligand that specifically labels rat P2X7 receptors.
ESTHER : Donnelly-Roberts_2009_Neuropharmacol_56_223
PubMedSearch : Donnelly-Roberts_2009_Neuropharmacol_56_223
PubMedID: 18602931

Title : Synthesis and in vitro activity of 1-(2,3-dichlorophenyl)-N-(pyridin-3-ylmethyl)-1H-1,2,4-triazol-5-amine and 4-(2,3-dichlorophenyl)-N-(pyridin-3-ylmethyl)-4H-1,2,4-triazol-3-amine P2X7 antagonists - Florjancic_2008_Bioorg.Med.Chem.Lett_18_2089
Author(s) : Florjancic AS , Peddi S , Perez-Medrano A , Li B , Namovic MT , Grayson G , Donnelly-Roberts D , Jarvis MF , Carroll WA
Ref : Bioorganic & Medicinal Chemistry Lett , 18 :2089 , 2008
Abstract : A novel series of aminotriazole-based P2X(7) antagonists was synthesized, and their structure-activity relationships (SAR) were investigated for activity at both human and rat P2X(7) receptors. Most compounds showed greater potency at the human receptor although several analogs were discovered with potent activity (pIC(50) > or = 7.5) at both human and rat P2X(7).
ESTHER : Florjancic_2008_Bioorg.Med.Chem.Lett_18_2089
PubMedSearch : Florjancic_2008_Bioorg.Med.Chem.Lett_18_2089
PubMedID: 18272366

Title : Synthesis and activity of N-cyanoguanidine-piperazine P2X7 antagonists - Betschmann_2008_Bioorg.Med.Chem.Lett_18_3848
Author(s) : Betschmann P , Bettencourt B , Donnelly-Roberts D , Friedman M , George J , Hirst G , Josephsohn N , Konopacki D , Li B , Maull J , Morytko MJ , Moore NS , Namovic M , Rafferty P , Salmeron-Garcia JA , Tarcsa E , Wang L , Woller K
Ref : Bioorganic & Medicinal Chemistry Lett , 18 :3848 , 2008
Abstract : A novel series of cyanoguanidine-piperazine P2X(7) antagonists were identified and structure-activity relationship (SAR) studies described. Compounds were assayed for activity at human and rat P2X(7) receptors in addition to their ability to inhibit IL-1 beta release from stimulated human whole blood cultures. Compound 27 possesses potent activity (0.12 microM) in this latter assay and demonstrates moderate clearance in-vivo.
ESTHER : Betschmann_2008_Bioorg.Med.Chem.Lett_18_3848
PubMedSearch : Betschmann_2008_Bioorg.Med.Chem.Lett_18_3848
PubMedID: 18595695

Title : Painful purinergic receptors - Donnelly-Roberts_2008_J.Pharmacol.Exp.Ther_324_409
Author(s) : Donnelly-Roberts D , McGaraughty S , Shieh CC , Honore P , Jarvis MF
Ref : Journal of Pharmacology & Experimental Therapeutics , 324 :409 , 2008
Abstract : Multiple P2 receptor-mediated mechanisms exist by which ATP can alter nociceptive sensitivity following tissue injury. Evidence from a variety of experimental strategies, including genetic disruption studies and the development of selective antagonists, has indicated that the activation of P2X receptor subtypes, including P2X(3), P2X(2/3), P2X(4) and P2X(7), and P2Y (e.g., P2Y(2)) receptors, can modulate pain. For example, administration of a selective P2X(3) antagonist, A-317491, has been shown to effectively block both hyperalgesia and allodynia in different animal models of pathological pain. Intrathecally delivered antisense oligonucleotides targeting P2X(4) receptors decrease tactile allodynia following nerve injury. Selective antagonists for the P2X(7) receptor also reduce sensitization in animal models of inflammatory and neuropathic pain, providing evidence that purinergic glial-neural interactions are important modulators of noxious sensory neurotransmission. Furthermore, activation of P2Y(2) receptors leads to sensitization of polymodal transient receptor potential-1 receptors. Thus, ATP acting at multiple purinergic receptors, either directly on neurons (e.g., P2X(3), P2X(2/3), and P2Y receptors) or indirectly through neural-glial cell interactions (P2X(4) and P2X(7) receptors), alters nociceptive sensitivity. The development of selective antagonists for some of these P2 receptors has greatly aided investigations into the nociceptive role of ATP. This perspective highlights some of the recent advances to identify selective P2 receptor ligands, which has enhanced the investigation of ATP-related modulation of pain sensitivity.
ESTHER : Donnelly-Roberts_2008_J.Pharmacol.Exp.Ther_324_409
PubMedSearch : Donnelly-Roberts_2008_J.Pharmacol.Exp.Ther_324_409
PubMedID: 18042830

Title : Synthesis and in vitro activity of N'-cyano-4-(2-phenylacetyl)-N-o-tolylpiperazine-1-carboximidamide P2X7 antagonists - Morytko_2008_Bioorg.Med.Chem.Lett_18_2093
Author(s) : Morytko MJ , Betschmann P , Woller K , Ericsson A , Chen H , Donnelly-Roberts D , Namovic MT , Jarvis MF , Carroll WA , Rafferty P
Ref : Bioorganic & Medicinal Chemistry Lett , 18 :2093 , 2008
Abstract : A novel series of cyanoguanidine-piperazine P2X(7) antagonists was designed based upon the structure of A-740003. Structure-activity relationship (SAR) studies focused on the piperazine moiety and the right hand side substitution. Compounds were assayed for activity at human and rat P2X(7) receptors and compound 29 was found to possess potent activity (IC(50)=30-60 nM) at both species.
ESTHER : Morytko_2008_Bioorg.Med.Chem.Lett_18_2093
PubMedSearch : Morytko_2008_Bioorg.Med.Chem.Lett_18_2093
PubMedID: 18272365

Title : Structure-activity relationship studies on N'-aryl carbohydrazide P2X7 antagonists - Nelson_2008_J.Med.Chem_51_3030
Author(s) : Nelson DW , Sarris K , Kalvin DM , Namovic MT , Grayson G , Donnelly-Roberts D , Harris R , Honore P , Jarvis MF , Faltynek CR , Carroll WA
Ref : Journal of Medicinal Chemistry , 51 :3030 , 2008
Abstract : N'-aryl acyl hydrazides were identified as P2X7 receptor antagonists. Structure-activity relationship (SAR) studies evaluated functional activity by monitoring calcium flux inhibition in cell lines expressing recombinant human and rat P2X7 receptors. Selected analogs were assayed in vitro for their capacity to inhibit release of cytokine IL-1beta. Compounds with potent antagonist function were evaluated in vivo using the zymosan-induced peritonitis model. A representative compound effectively attenuated mechanical allodynia in a rat model of neuropathic pain.
ESTHER : Nelson_2008_J.Med.Chem_51_3030
PubMedSearch : Nelson_2008_J.Med.Chem_51_3030
PubMedID: 18438986

Title : Novel and potent 3-(2,3-dichlorophenyl)-4-(benzyl)-4H-1,2,4-triazole P2X7 antagonists - Carroll_2007_Bioorg.Med.Chem.Lett_17_4044
Author(s) : Carroll WA , Kalvin DM , Perez Medrano A , Florjancic AS , Wang Y , Donnelly-Roberts D , Namovic MT , Grayson G , Honore P , Jarvis MF
Ref : Bioorganic & Medicinal Chemistry Lett , 17 :4044 , 2007
Abstract : Structure-activity relationship (SAR) studies were conducted around early tetrazole-based leads 3 and 4. Replacements for the tetrazole core were investigated and the pendant benzyl substitution was reoptimized with a triazole isostere. Triazole-based P2X(7) antagonists were identified with similar potency to the lead compound 4 but with improved physiochemical properties. Compound 12 was active in a rat model of neuropathic pain.
ESTHER : Carroll_2007_Bioorg.Med.Chem.Lett_17_4044
PubMedSearch : Carroll_2007_Bioorg.Med.Chem.Lett_17_4044
PubMedID: 17482819

Title : P2X7-related modulation of pathological nociception in rats - McGaraughty_2007_Neurosci_146_1817
Author(s) : McGaraughty S , Chu KL , Namovic MT , Donnelly-Roberts D , Harris RR , Zhang XF , Shieh CC , Wismer CT , Zhu CZ , Gauvin DM , Fabiyi AC , Honore P , Gregg RJ , Kort ME , Nelson DW , Carroll WA , Marsh K , Faltynek CR , Jarvis MF
Ref : Neuroscience , 146 :1817 , 2007
Abstract : Growing evidence supports a role for the immune system in the induction and maintenance of chronic pain. ATP is a key neurotransmitter in this process. Recent studies demonstrate that the glial ATP receptor, P2X7, contributes to the modulation of pathological pain. To further delineate the endogenous mechanisms that are involved in P2X7-related antinociception, we utilized a selective P2X7 receptor antagonist, A-438079, in a series of in vivo and in vitro experiments. Injection of A-438079 (10-300 micromol/kg, i.p.) was anti-allodynic in three different rat models of neuropathic pain and it attenuated formalin-induced nocifensive behaviors. Using in vivo electrophysiology, A-438079 (80 micromol/kg, i.v.) reduced noxious and innocuous evoked activity of different classes of spinal neurons (low threshold, nociceptive specific, wide dynamic range) in neuropathic rats. The effects of A-438079 on evoked firing were diminished or absent in sham rats. Spontaneous activity of all classes of spinal neurons was also significantly reduced by A-438079 in neuropathic but not sham rats. In vitro, A-438079 (1 microM) blocked agonist-induced (2,3-O-(4-benzoylbenzoyl)-ATP, 30 microM) current in non-neuronal cells taken from the vicinity of the dorsal root ganglia. Furthermore, A-438079 dose-dependently (0.3-3 microM) decreased the quantity of the cytokine, interleukin-1beta, released from peripheral macrophages. Thus, ATP, acting through the P2X7 receptor, exerts a wide-ranging influence on spinal neuronal activity following a chronic injury. Antagonism of the P2X7 receptor can in turn modulate central sensitization and produce antinociception in animal models of pathological pain. These effects are likely mediated through immuno-neural interactions that affect the release of endogenous cytokines.
ESTHER : McGaraughty_2007_Neurosci_146_1817
PubMedSearch : McGaraughty_2007_Neurosci_146_1817
PubMedID: 17478048

Title : Discovery of P2X7 receptor-selective antagonists offers new insights into P2X7 receptor function and indicates a role in chronic pain states - Donnelly-Roberts_2007_Br.J.Pharmacol_151_571
Author(s) : Donnelly-Roberts D , Jarvis MF
Ref : British Journal of Pharmacology , 151 :571 , 2007
Abstract : ATP-sensitive P2X(7) receptors are localized on cells of immunological origin including peripheral macrophages and glial cells in the CNS. Activation of P2X(7) receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1beta and following prolonged agonist exposure, the formation of cytolytic pores in plasma membranes. Both the localization and functional consequences of P2X(7) receptor activation indicate a role in inflammatory processes. The phenotype of P2X(7) receptor gene-disrupted mice also indicates that P2X(7) receptor activation contributes to ongoing inflammation. More recently, P2X(7) receptor knockout data has also suggested a specific role in inflammatory and neuropathic pain states. The recent discovery of potent and highly selective antagonists for P2X(7) receptors has helped to further clarify P2X receptor pharmacology, expanded understanding of P2X(7) receptor signaling, and offers new evidence that P2X(7) receptors play a specific role in nociceptive signaling in chronic pain states. In this review, we incorporate the recent discoveries of novel P2X(7) receptor-selective antagonists with a brief update on P2X(7) receptor pharmacology and its therapeutic potential.
ESTHER : Donnelly-Roberts_2007_Br.J.Pharmacol_151_571
PubMedSearch : Donnelly-Roberts_2007_Br.J.Pharmacol_151_571
PubMedID: 17471177

Title : A-85380: a pharmacological probe for the preclinical and clinical investigation of the alphabeta neuronal nicotinic acetylcholine receptor - Rueter_2006_CNS.Drug.Rev_12_100
Author(s) : Rueter LE , Donnelly-Roberts D , Curzon P , Briggs CA , Anderson DJ , Bitner RS
Ref : CNS Drug Rev , 12 :100 , 2006
Abstract : A-85380 [3-(2(s)-azetidinylmethoxy) pyridine] is a neuronal nicotinic acetylcholine receptor (nAChR) agonist that has been a useful tool in the investigation of the function of nAChRs in both preclinical and clinical studies. Amongst nAChR subtypes, A-85380 shows selectivity for the alpha(4)beta(2) vs. the alpha(7) or alpha(1)beta(1)deltagamma nAChRs. In functional in vitro cation flux assays, A-85380 is a potent and full agonist. A-85380 has a broad-spectrum analgesic profile with efficacy in acute, persistent, and neuropathic pain models. As demonstrated using selective nAChR antagonists or alpha(4) antisense, the alpha(4)beta(2) nAChR mediates the analgesic effects of A-85380. Interestingly, the site of action depends upon the type of pain as antinociception is mediated by descending inhibition into the spinal cord whereas anti-allodynia in neuropathic pain is mediated at both central and peripheral sites. Radiolabelled forms of A-85380 have been developed and shown to be safe for use in vivo in humans. In clinical studies using positron and photon emission tomography, marked decreases in alpha(4)beta(2) nAChRs have been seen in patients with Parkinson's and Alzheimer's disease. Although not developed as a therapeutic agent, A-85380 has proven to be an important component in the development of novel nAChR ligands for the treatment of pain and other disorders.
ESTHER : Rueter_2006_CNS.Drug.Rev_12_100
PubMedSearch : Rueter_2006_CNS.Drug.Rev_12_100
PubMedID: 16958984

Title : A-740003 [N-(1-{[(cyanoimino)(5-quinolinylamino) methyl]amino}-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide], a novel and selective P2X7 receptor antagonist, dose-dependently reduces neuropathic pain in the rat - Honore_2006_J.Pharmacol.Exp.Ther_319_1376
Author(s) : Honore P , Donnelly-Roberts D , Namovic MT , Hsieh G , Zhu CZ , Mikusa JP , Hernandez G , Zhong C , Gauvin DM , Chandran P , Harris R , Medrano AP , Carroll W , Marsh K , Sullivan JP , Faltynek CR , Jarvis MF
Ref : Journal of Pharmacology & Experimental Therapeutics , 319 :1376 , 2006
Abstract : ATP-sensitive P2X(7) receptors are localized on cells of immunological origin including glial cells in the central nervous system. Activation of P2X(7) receptors leads to rapid changes in intracellular calcium concentrations, release of the proinflammatory cytokine interleukin-1beta (IL-1beta), and following prolonged agonist exposure, cytolytic plasma membrane pore formation. P2X(7) knockout mice show reduced inflammation as well as decreased nociceptive sensitivity following peripheral nerve injury. A-740003 (N-(1-{[(cyanoimino)(5-quinolinylamino) methyl] amino}-2,2-dimethylpropyl)-2-(3,4-dimethoxyphenyl)acetamide) is a novel competitive antagonist of P2X(7) receptors (IC(50) values = 40 nM for human and 18 nM for rat) as measured by agonist-stimulated changes in intracellular calcium concentrations. A-740003 showed weak or no activity (IC(50) > 10 muM) at other P2 receptors and an array of other neurotransmitter and peptide receptors, ion channels, reuptake sites, and enzymes. A-740003 potently blocked agonist-evoked IL-1beta release (IC(50) = 156 nM) and pore formation (IC(50) = 92 nM) in differentiated human THP-1 cells. Systemic administration of A-740003 produced dose-dependent antinociception in a spinal nerve ligation model (ED(50) = 19 mg/kg i.p.) in the rat. A-740003 also attenuated tactile allodynia in two other models of neuropathic pain, chronic constriction injury of the sciatic nerve and vincristine-induced neuropathy. In addition, A-740003 effectively reduced thermal hyperalgesia observed following intraplantar administration of carrageenan or complete Freund's adjuvant (ED(50) = 38-54 mg/kg i.p.). A-740003 was ineffective in attenuating acute thermal nociception in normal rats and did not alter motor performance at analgesic doses. These data demonstrate that selective blockade of P2X(7) receptors in vivo produces significant antinociception in animal models of neuropathic and inflammatory pain.
ESTHER : Honore_2006_J.Pharmacol.Exp.Ther_319_1376
PubMedSearch : Honore_2006_J.Pharmacol.Exp.Ther_319_1376
PubMedID: 16982702

Title : 1-aryl-3-(4-pyridine-2-ylpiperazin-1-yl)propan-1-one oximes as potent dopamine D4 receptor agonists for the treatment of erectile dysfunction - Kolasa_2006_J.Med.Chem_49_5093
Author(s) : Kolasa T , Matulenko MA , Hakeem AA , Patel MV , Mortell K , Bhatia P , Henry R , Nakane M , Hsieh GC , Terranova MA , Uchic ME , Miller LN , Chang R , Donnelly-Roberts D , Namovic MT , Hollingsworth PR , Martino B , El Kouhen O , Marsh KC , Wetter JM , Moreland RB , Brioni JD , Stewart AO
Ref : Journal of Medicinal Chemistry , 49 :5093 , 2006
Abstract : A new series of dopamine D4 receptor agonists, 1-aryl-3-(4-pyridinepiperazin-1-yl)propanone oximes, was designed through the modification of known dopamine D4 receptor agonist PD 168077. Replacement of the amide group with a methylene-oxime moiety produced compounds with improved stability and efficacy. Structure-activity relationsips (SAR) of the aromatic ring linked to the N-4-piperazine ring confirmed the superiority of 2-pyridine as a core for D4 agonist activity. A two-methylene linker between the oxime group and the N-1-piperazine ring displayed the best profile. New dopamine D4 receptor agonists, exemplified by (E)-1-(4-chlorophenyl)-3-(4-pyridin-2-ylpiperazin-1-yl)propan-1-one O-methyloxime (59a) and (E)-1-(3-chloro-4-fluorophenyl)-3-(4-pyridin-2-ylpiperazin-1-yl)propan-1-one O-methyloxime (64a), exhibited favorable pharmacokinetic profiles and showed oral bioavailability in rat and dog. Subsequent evaluation of 59a in the rat penile erection model revealed in vivo activity, comparable in efficacy to apomorphine. Our results suggest that the oximes provide a novel structural linker for 4-arylpiperazine-based D4 agonists, possessing leadlike quality and with potential to develop a new class of potent and selective dopamine D4 receptor agonists.
ESTHER : Kolasa_2006_J.Med.Chem_49_5093
PubMedSearch : Kolasa_2006_J.Med.Chem_49_5093
PubMedID: 16913699

Title : Structure-activity relationship studies on a series of novel, substituted 1-benzyl-5-phenyltetrazole P2X7 antagonists - Nelson_2006_J.Med.Chem_49_3659
Author(s) : Nelson DW , Gregg RJ , Kort ME , Perez-Medrano A , Voight EA , Wang Y , Grayson G , Namovic MT , Donnelly-Roberts D , Niforatos W , Honore P , Jarvis MF , Faltynek CR , Carroll WA
Ref : Journal of Medicinal Chemistry , 49 :3659 , 2006
Abstract : 1-Benzyl-5-aryltetrazoles were discovered to be novel antagonists for the P2X(7) receptor. Structure-activity relationship (SAR) studies were conducted around both the benzyl and phenyl moieties. In addition, the importance of the regiochemical substitution on the tetrazole was examined. Compounds were evaluated for activity to inhibit calcium flux in both human and rat recombinant P2X(7) cell lines using fluorometric imaging plate reader technology. Analogues were also assayed for their ability to inhibit IL-1beta release and to inhibit P2X(7)-mediated pore formation in human THP-1 cells. Compound 15d was advanced to efficacy studies in a model of neuropathic pain where significant reversal of mechanical allodynia was observed at doses that did not affect motor coordination.
ESTHER : Nelson_2006_J.Med.Chem_49_3659
PubMedSearch : Nelson_2006_J.Med.Chem_49_3659
PubMedID: 16759108

Title : Discovery of 3-methyl-N-(1-oxy-3',4',5',6'-tetrahydro-2'H-[2,4'-bipyridine]-1'-ylmethyl)benzam ide (ABT-670), an orally bioavailable dopamine D4 agonist for the treatment of erectile dysfunction - Patel_2006_J.Med.Chem_49_7450
Author(s) : Patel MV , Kolasa T , Mortell K , Matulenko MA , Hakeem AA , Rohde JJ , Nelson SL , Cowart MD , Nakane M , Miller LN , Uchic ME , Terranova MA , El-Kouhen OF , Donnelly-Roberts D , Namovic MT , Hollingsworth PR , Chang R , Martino BR , Wetter JM , Marsh KC , Martin R , Darbyshire JF , Gintant G , Hsieh GC , Moreland RB , Sullivan JP , Brioni JD , Stewart AO
Ref : Journal of Medicinal Chemistry , 49 :7450 , 2006
Abstract : The goal of this study was to identify a structurally distinct D(4)-selective agonist with superior oral bioavailability to our first-generation clinical candidate 1a (ABT-724) for the potential treatment of erectile dysfunction. Arylpiperazines such as (heteroarylmethyl)piperazine 1a, benzamide 2, and acetamides such as 3a,b exhibit poor oral bioavailability. Structure-activity relationship (SAR) studies with the arylpiperidine template provided potent partial agonists such as 4d and 5k that demonstrated no improvement in oral bioavailability. Further optimization with the (N-oxy-2-pyridinyl)piperidine template led to the discovery of compound 6b (ABT-670), which exhibited excellent oral bioavailability in rat, dog, and monkey (68%, 85%, and 91%, respectively) with comparable efficacy, safety, and tolerability to 1a. The N-oxy-2-pyridinyl moiety not only provided the structural motif required for agonist function but also reduced metabolism rates. The SAR study leading to the discovery of 6b is described herein.
ESTHER : Patel_2006_J.Med.Chem_49_7450
PubMedSearch : Patel_2006_J.Med.Chem_49_7450
PubMedID: 17149874

Title : Pharmacological characterization of P2X7 receptors in rat peritoneal cells - Chen_2005_Inflamm.Res_54_119
Author(s) : Chen YW , Donnelly-Roberts D , Namovic MT , Gintant GA , Cox BF , Jarvis MF , Harris RR
Ref : Inflamm Res , 54 :119 , 2005
Abstract : OBJECTIVE AND DESIGN: P2X(7) receptor activation by ATP results in the release of IL-1beta and IL-18. Prolonged stimulation can lead to pore formation and cell death. In this study we pharmacologically characterized P2X(7) receptors on rat peritoneal cells (RPC) and on 1321N1 cells transfected with rat P2X(7) receptor (1321rP2X(7)-11). MATERIALS AND
METHODS: RPC were isolated from rats by lavage. P2X(7) agonist induced pore formation in RPC was measured by EtBr uptake. P2X(7)-stimulated pore formation and Ca(++) influx in 1321rP2X(7)-11 cells were measured by a fluorometric imaging plate reader. The effects of pyridoxal phosphate-6-azo phenyl -2'-4'-disulfonic acid (PPADS) on pore formation and Ca(++) influx were examined in both RPC and 1321rP2X(7)-11. P2X(7)-mediated IL-1beta release in RPC and the effect of PPADS were determined.
RESULTS: RPC express functional P2X(7) receptors that were activated by ATP analogs with a rank order of potency of 2'- 3'-O-(4-Benzoylbenzoyl) adenosine 5'-triphosphate (BzATP) > ATP > alpha,beta-methylene ATP. Activation of P2X(7) receptors by BzATP was inhibited by PPADS. Similar results were also obtained in 1321rP2X(7)-11 cells. Activation of P2X(7) receptors on RPC resulted in IL-1 beta secretion, which was inhibited by PPADS.
CONCLUSIONS: RPC express functional P2X(7) receptors that form pores and mediate the release of IL-1beta.
ESTHER : Chen_2005_Inflamm.Res_54_119
PubMedSearch : Chen_2005_Inflamm.Res_54_119
PubMedID: 15883745

Title : 2-[4-(3,4-Dimethylphenyl)piperazin-1-ylmethyl]-1H benzoimidazole (A-381393), a selective dopamine D4 receptor antagonist - Nakane_2005_Neuropharmacol_49_112
Author(s) : Nakane M , Cowart MD , Hsieh GC , Miller L , Uchic ME , Chang R , Terranova MA , Donnelly-Roberts D , Namovic MT , Miller TR , Wetter JM , Marsh K , Stewart AO , Brioni JD , Moreland RB
Ref : Neuropharmacology , 49 :112 , 2005
Abstract : 2-[4-(3,4-Dimethylphenlyl)piperazin-1-ylmethyl]-1H benzoimidazole (A-381393) was identified as a potent dopamine D4 receptor antagonist with excellent receptor selectivity. [3H]-spiperone competition binding assays showed that A-381393 potently bound to membrane from cells expressing recombinant human dopamine D4.4 receptor (Ki=1.5 nM), which was 20-fold higher than that of clozapine (Ki=30.4 nM). A-381393 exhibited highly selective binding for the dopamine D4.4 receptor (>2700-fold) when compared to D1, D2, D3 and D5 dopamine receptors. Furthermore, in comparison to clozapine and L-745870, A-381393 exhibits better receptor selectivity, showing no affinity up to 10 microM for a panel of more than 70 receptors and channels, with the exception of moderate affinity for 5-HT2A (Ki=370 nM). A-381393 potently inhibited the functional activity of agonist-induced GTP-gamma-S binding assay and 1 microM dopamine induced-Ca2+ flux in human dopamine D4.4 receptor expressing cells, but not in human dopamine D2L or D3 receptor cells. In contrast to L-745870, A-381393 did not exhibit any significant intrinsic activity in a D4.4 receptor. In vivo, A-381393 has good brain penetration after subcutaneous administration. A-381393 inhibited penile erection induced by the selective D4 agonist PD168077 in conscious rats. Thus, A-381393 is a novel selective D4 antagonist that will enhance the ability to study dopamine D4 receptors both in vitro and in vivo.
ESTHER : Nakane_2005_Neuropharmacol_49_112
PubMedSearch : Nakane_2005_Neuropharmacol_49_112
PubMedID: 15992586

Title : ABT-089: pharmacological properties of a neuronal nicotinic acetylcholine receptor agonist for the potential treatment of cognitive disorders - Rueter_2004_CNS.Drug.Rev_10_167
Author(s) : Rueter LE , Anderson DJ , Briggs CA , Donnelly-Roberts D , Gintant GA , Gopalakrishnan M , Lin NH , Osinski MA , Reinhart GA , Buckley MJ , Martin RL , McDermott JS , Preusser LC , Seifert TR , Su Z , Cox BF , Decker MW , Sullivan JP
Ref : CNS Drug Rev , 10 :167 , 2004
Abstract : ABT-089 [2-methyl-3-(2-(S)-pyrrolidinylmethoxy)pyridine dihydrochloride salt] is a selective neuronal nicotinic receptor (NNR) modulator with cognitive enhancing properties in animal models of cognitive functioning. Amongst NNR subtypes, ABT-089 shows selectivity for the cytisine binding site on the alpha4beta2 receptor subtype as compared to the alpha-bungarotoxin (alpha-BgT) binding sites on the alpha7 and alpha1beta1deltagamma receptor subtypes. In functional in vitro electrophysiological and cation flux assays, ABT-089 displays differential activity including agonism, partial agonism and antagonism depending upon the NNR subtype and assay. ABT-089 is as potent and efficacious as (-)-nicotine at evoking acetylcholine (ACh) release from hippocampal synaptosomes. Furthermore, ABT-089 is neuroprotective against excitotoxic glutamate insults, with even greater potency seen after chronic treatment. Similarly, ABT-089 is effective in models of cognitive functioning, including enhancement of baseline functioning as well as improvement of impaired cognitive functioning seen following septal lesioning and natural aging. In neuroprotective assays the compound is most potent by chronic administration. In stark contrast to the positive effects in the cognitive models, ABT-089 shows little propensity to induce adverse effects such as ataxia, hypothermia, seizures, cardiovascular or gastrointestinal side effects. Together these data suggest that ABT-089 is a NNR modulator with the potential for treating cognitive disorders with markedly limited adverse cardiovascular and gastrointestinal side effects.
ESTHER : Rueter_2004_CNS.Drug.Rev_10_167
PubMedSearch : Rueter_2004_CNS.Drug.Rev_10_167
PubMedID: 15179445

Title : In vitro and in vivo effects of an alpha3 neuronal nicotinic acetylcholine receptor antisense oligonucleotide - Adams_2004_Brain.Res.Mol.Brain.Res_129_67
Author(s) : Adams MR , Nikkel AL , Donnelly-Roberts D , Watt AT , Johnston JF , Cowsert LM , Butler M , Kroeger PE , Frost L , Curzon P , Decker MW , Bitner RS
Ref : Brain Research Mol Brain Res , 129 :67 , 2004
Abstract : In the mammalian central nervous system (CNS), a family of alpha and beta subunits (alpha2-7, beta2-4) assemble to form both hetero- and homopentameric neuronal nicotinic acetylcholine receptors (nAChRs). In contrast to alpha4beta2 and alpha7, the predominant brain subtypes, far less is known regarding the functional expression and significance of alpha3-containing nAChRs in the CNS. In trying to better understand the role alpha3 in the CNS, an antisense knockdown strategy was utilized in the present studies. Specifically, Isis 106567 was identified out of 80 antisense oligonucleotides (aONs) designed and screened for their ability to reduce alpha3 mRNA expression in PC-12 cells. In addition to reducing alpha3 mRNA by greater than 75%, Isis 106567 attenuated nicotine-induced calcium influx in alpha3-expressing F11 cells. In vivo studies revealed significant reduction of alpha3 mRNA levels in both thalamus and medial habenula, regions known to express alpha3, following continuous (7 days) intracerebroventricular (i.c.v.) infusion of Isis 106567 in rats. Consistent with functional alpha3 knockdown, epibatidine-induced c-Fos expression in the medial habenula was attenuated in aON-treated rats. Known physiological responses elicited by epibatidine, such as hypothermia and micturition, were not affected by alpha3 aON treatment. However, the incidence of epibatidine-induced seizures was reduced in alpha3-antisense aON-treated rats, suggesting that alpha3 may be involved in mediating seizures produced by the nAChR agonist. Results of our studies suggest that Isis 106567 may be a useful in vivo tool for characterizing the functional significance of alpha3 expression in the CNS.
ESTHER : Adams_2004_Brain.Res.Mol.Brain.Res_129_67
PubMedSearch : Adams_2004_Brain.Res.Mol.Brain.Res_129_67
PubMedID: 15469883

Title : Dopamine D4 ligands and models of receptor activation: 2-(4-pyridin-2-ylpiperazin-1-ylmethyl)-1H-benzimidazole and related heteroarylmethylarylpiperazines exhibit a substituent effect responsible for additional efficacy tuning - Stewart_2004_J.Med.Chem_47_2348
Author(s) : Stewart AO , Cowart MD , Moreland RB , Latshaw SP , Matulenko MA , Bhatia PA , Wang X , Daanen JF , Nelson SL , Terranova MA , Namovic MT , Donnelly-Roberts D , Miller LN , Nakane M , Sullivan JP , Brioni JD
Ref : Journal of Medicinal Chemistry , 47 :2348 , 2004
Abstract : A series of subtype selective dopamine D(4) receptor ligands from the hetroarylmethylphenylpiperazine class have been discovered that exhibit a remarkable structure-activity relationship (SAR), revealing a substituent effect in which regiosubstitution on the terminal arylpiperazine ring can modulate functional or intrinsic activity. Other structure-dependent efficacy studies in the dopamine D(4) field have suggested a critical interaction of the heteroarylmethyl moiety with specific protein microdomains in controlling intrinsic activity. Our studies indicate that for some binding orientations, the phenylpiperazine moiety also plays a key role in determining efficacy. These data also implicate a kinetic or efficiency term, contained within measured functional affinities for agonists, which support a sequential binding and conformational stabilization model for receptor activation. The structural similarity between partial agonist and antagonist, within this subset of ligands, and lack of bioisosterism for this substituent effect are key phenomena for these hypotheses.
ESTHER : Stewart_2004_J.Med.Chem_47_2348
PubMedSearch : Stewart_2004_J.Med.Chem_47_2348
PubMedID: 15084133

Title : Central mechanisms regulating penile erection in conscious rats: the dopaminergic systems related to the proerectile effect of apomorphine - Hsieh_2004_J.Pharmacol.Exp.Ther_308_330
Author(s) : Hsieh GC , Hollingsworth PR , Martino B , Chang R , Terranova MA , O'Neill AB , Lynch JJ , Moreland RB , Donnelly-Roberts D , Kolasa T , Mikusa JP , McVey JM , Marsh KC , Sullivan JP , Brioni JD
Ref : Journal of Pharmacology & Experimental Therapeutics , 308 :330 , 2004
Abstract : Apomorphine has been used as a pharmacological probe of dopaminergic receptors in a variety of central nervous system disorders. The utility of apomorphine as an agent for the treatment of erectile dysfunction has also been demonstrated clinically. Apomorphine is a nonselective dopaminergic receptor agonist with potent binding affinity (Ki) of 101, 32, 26, 2.6, and 10 nM for D1, D2, D3, D4, and D5, respectively. When administered either subcutaneously (s.c.) or intracerebroventricularly (i.c.v.), apomorphine fully evoked penile erections in conscious rats with maximum effect at 0.1 micromol/kg s.c. and 3 nmol/rat i.c.v., respectively. Apomorphine was less efficacious when injected intrathecally (i.t.) to L4-L6 spinal levels (50% at 30-100 nmol/rat i.t.). Penile erection facilitated by apomorphine was blocked by haloperidol and clozapine (i.p. and i.c.v.) but not by domperidone (a peripherally acting dopaminergic receptor antagonist). In this model using conscious rats, penile erection was significantly induced by quinpirole (D2-D3-D4 receptor agonist), but not by R(+)-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol (SKF38393) and R(+)-6-chloro-7,8-dihydroxy-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzapine (SKF81297) (D1 receptor agonists), or a D2 receptor agonist R-5,6-dihydro-N,N-dimethyl-4H-imidazo[4,5,1-ij]quinolin-5-amine (PNU-95666E). The role of D4 receptors in penile erection was demonstrated using selective D4 receptor agonists [(4-phenylpiperazinyl)-methyl]benzamide (PD168077) and 5-fluoro-2-[[4-(2-pyridinyl)-1-piperazinyl]methyl]-1H-indole (CP226269), whether administered systemically (s.c.) or locally in the brain (i.c.v.). The ability of apomorphine to activate D3 receptors in relation to its proerectile activity remains to be elucidated by use of selective subtype agonists. These results suggest that the proerectile action of apomorphine in rats is mediated at supraspinal levels and that this effect is not mimicked by a D2 receptor agonist but associated with activation of D4 receptors.
ESTHER : Hsieh_2004_J.Pharmacol.Exp.Ther_308_330
PubMedSearch : Hsieh_2004_J.Pharmacol.Exp.Ther_308_330
PubMedID: 14569075

Title : Activation of dopamine D4 receptors by ABT-724 induces penile erection in rats - Brioni_2004_Proc.Natl.Acad.Sci.U.S.A_101_6758
Author(s) : Brioni JD , Moreland RB , Cowart M , Hsieh GC , Stewart AO , Hedlund P , Donnelly-Roberts D , Nakane M , Lynch JJ, 3rd , Kolasa T , Polakowski JS , Osinski MA , Marsh K , Andersson KE , Sullivan JP
Ref : Proc Natl Acad Sci U S A , 101 :6758 , 2004
Abstract : Apomorphine, a nonselective dopamine receptor agonist, facilitates penile erection and is effective in patients suffering from erectile dysfunction. The specific dopamine receptor subtype(s) responsible for its erectogenic effect is not known. Here we report that the dopamine D(4) receptor plays a role in the regulation of penile function. ABT-724 is a selective dopamine D(4) receptor agonist that activates human dopamine D(4) receptors with an EC(50) of 12.4 nM and 61% efficacy, with no effect on dopamine D(1), D(2), D(3), or D(5) receptors. ABT-724 dose-dependently facilitates penile erection when given s.c. to conscious rats, an effect that is blocked by haloperidol and clozapine but not by domperidone. A proerectile effect is observed after intracerebroventricular but not intrathecal administration, suggesting a supraspinal site of action. s.c. injections of ABT-724 increase intracavernosal pressure in awake freely moving rats. In the presence of sildenafil, a potentiation of the proerectile effect of ABT-724 is observed in conscious rats. The ability of ABT-724 to facilitate penile erection together with the favorable side-effect profile indicates that ABT-724 could be useful for the treatment of erectile dysfunction.
ESTHER : Brioni_2004_Proc.Natl.Acad.Sci.U.S.A_101_6758
PubMedSearch : Brioni_2004_Proc.Natl.Acad.Sci.U.S.A_101_6758
PubMedID: 15087502

Title : Synthesis and functional activity of (2-aryl-1-piperazinyl)-N-(3-methylphenyl)acetamides: selective dopamine D4 receptor agonists - Matulenko_2004_Bioorg.Med.Chem_12_3471
Author(s) : Matulenko MA , Hakeem AA , Kolasa T , Nakane M , Terranova MA , Uchic ME , Miller LN , Chang R , Donnelly-Roberts D , Namovic MT , Moreland RB , Brioni JD , Stewart AO
Ref : Bioorganic & Medicinal Chemistry , 12 :3471 , 2004
Abstract : Diaryl piperazine acetamides were identified as potent and selective dopamine D(4) receptor agonists. Our strategy is based on an amide bond reversal of an acid sensitive, dopamine D(4) receptor partial agonist, PD 168077. This reversal provided compounds with excellent potency and improved stability. Systematic evaluation of the substitution on the aryl piperazine portion revealed a significant effect on functional activity. The synthesis and biological activity of these new dopamine D(4) agonists is discussed.
ESTHER : Matulenko_2004_Bioorg.Med.Chem_12_3471
PubMedSearch : Matulenko_2004_Bioorg.Med.Chem_12_3471
PubMedID: 15186832

Title : Discovery of 2-(4-pyridin-2-ylpiperazin-1-ylmethyl)-1H-benzimidazole (ABT-724), a dopaminergic agent with a novel mode of action for the potential treatment of erectile dysfunction - Cowart_2004_J.Med.Chem_47_3853
Author(s) : Cowart M , Latshaw SP , Bhatia P , Daanen JF , Rohde J , Nelson SL , Patel M , Kolasa T , Nakane M , Uchic ME , Miller LN , Terranova MA , Chang R , Donnelly-Roberts D , Namovic MT , Hollingsworth PR , Martino BR , Lynch JJ, 3rd , Sullivan JP , Hsieh GC , Moreland RB , Brioni JD , Stewart AO
Ref : Journal of Medicinal Chemistry , 47 :3853 , 2004
Abstract : A new class of agents with potential utility for the treatment of erectile dysfunction has been discovered, guided by the hypothesis that selective D4 agonists are erectogenic but devoid of the side effects typically associated with dopaminergic agents. The lead agent 2-(4-pyridin-2-ylpiperazin-1-ylmethyl)-1H-benzimidazole (1, ABT-724) was discovered by optimization of a series of benzimidazole arylpiperazines. This highly selective D4 agonist was found to be very potent and efficacious in vivo, eliciting penile erections in rats at a dose of 0.03 micromol/kg, with a positive response rate of 77% erectile incidence. Even at high doses, it was devoid of side effects in animal models of central nervous system behaviors, emesis, or nausea. The structure-activity relationship of the parent benzimidazole series leading to 1 is described, with the detailed in vitro and in vivo profiles described. Distinctive structural features were discovered that are associated with D4 selective agonism in this series of analogues.
ESTHER : Cowart_2004_J.Med.Chem_47_3853
PubMedSearch : Cowart_2004_J.Med.Chem_47_3853
PubMedID: 15239663

Title : Synthesis and activity of 2-[4-(4-[3H]-2-cyanophenyl)piperazinyl]-N-(2,4,6-[3H]3-3-methylphenyl)acetamide: a selective dopamine D4 receptor agonist and radioligand - Matulenko_2004_Bioorg.Med.Chem.Lett_14_5095
Author(s) : Matulenko MA , Surber B , Fan L , Kolasa T , Nakane M , Terranova MA , Uchic ME , Miller LN , Chang R , Donnelly-Roberts D , Namovic MT , Moreland RB , Brioni JD , Stewart AO
Ref : Bioorganic & Medicinal Chemistry Lett , 14 :5095 , 2004
Abstract : The first selective dopamine D4 agonist radioligand is described. The synthesis of these piperazine radioligands relied on the transformation of brominated precursors 4a and 4b with tritium gas in the presence of a sensitive cyano functional group. The specific activity of these two radioligands was measured and [3H]6b found to be suitable for use in D4 saturation and competition binding studies. The synthesis, biological, and radioactivity of this new agonist radioligand as well as preliminary SAR will be discussed.
ESTHER : Matulenko_2004_Bioorg.Med.Chem.Lett_14_5095
PubMedSearch : Matulenko_2004_Bioorg.Med.Chem.Lett_14_5095
PubMedID: 15380206

Title : Comparative pharmacology of human dopamine D(2)-like receptor stable cell lines coupled to calcium flux through Galpha(qo5) - Moreland_2004_Biochem.Pharmacol_68_761
Author(s) : Moreland RB , Nakane M , Donnelly-Roberts D , Miller LN , Chang R , Uchic ME , Terranova MA , Gubbins EJ , Helfrich RJ , Namovic MT , El-Kouhen OF , Masters JN , Brioni JD
Ref : Biochemical Pharmacology , 68 :761 , 2004
Abstract : The goal of this study was to develop a new approach to study the pharmacology of the dopamine D(4) receptor that could be used in comparative studies with dopamine D(2) and D(3) receptors. Stable HEK-293 cell lines co-expressing recombinant human D(2L), D(3) or D(4) receptors along with Galpha(qo5) cDNA were prepared. Dopamine induced a robust, transient calcium signal in these cell lines with EC(50)s for D(2L), D(3) and D(4) of 18.0, 11.9 and 2.2 nM, respectively. Reported D(4)-selective agonists CP226269 and PD168077 were potent, partial D(4) agonists exhibiting 31-1700-fold selectivity for D(4) over D(3) or D(2). Non-selective D(2)-like agonists apomorphine and quinpirole showed full efficacy but did not discriminate across the three receptors. D(3)-selective agonists 7-hydroxy-DPAT and PD128907 were potent but non-selective D(2)-like agonists. The reported D(3) partial agonist BP-897 exhibited minimal agonist activity at D(3) but was a potent D(3) antagonist and a partial D(4) agonist. Other D(2)-like antagonists, haloperidol, clozapine, and domperidone showed concentration-dependent inhibition of dopamine responses at all three receptors with K(i) ranging from 0.05 to 48.3 nM. The D(3) selective antagonist S33084 and D(4)-selective antagonist L-745870 were highly selective for D(3) and D(4) receptors with K(b) of 0.7 and 0.1 nM, respectively. Stable co-expression of D(2)-like receptors with chimeric Galpha(qo5) proteins in HEK-293 cells is an efficient method to study receptor activation in a common cellular background and an efficient method for direct comparison of ligand affinity and efficacy across human D(2L), D(3) and D(4) receptors.
ESTHER : Moreland_2004_Biochem.Pharmacol_68_761
PubMedSearch : Moreland_2004_Biochem.Pharmacol_68_761
PubMedID: 15276084

Title : Mitogen-activated protein kinase and caspase signaling pathways are required for P2X7 receptor (P2X7R)-induced pore formation in human THP-1 cells - Donnelly-Roberts_2004_J.Pharmacol.Exp.Ther_308_1053
Author(s) : Donnelly-Roberts D , Namovic MT , Faltynek CR , Jarvis MF
Ref : Journal of Pharmacology & Experimental Therapeutics , 308 :1053 , 2004
Abstract : Brief activation of the ATP-sensitive P2X(7) receptor (P2X(7)R) stimulates the maturation and release of interleukin 1beta (IL-1beta)in macrophages, whereas prolonged agonist activation induces the formation of cytolytic pores in cell membranes. The present study investigated potential downstream mechanisms associated with native human P2X(7)R activation in lipopolysaccharide and interferon-gamma differentiated THP-1 cells. 2,3-O-(4-Benzoylbenzoyl)-ATP (BzATP)-induced pore formation (EC(50) = 35 microM) was blocked by a selective P2X(7)R antagonist, 1[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine (KN-62) (IC(50) = 44 nM) and by pyridoxal phosphate-6-azophenyl-2-4-disulfonic acid (PPADS) (IC(50) = 344 nM). KN-62 and PPADS also blocked BzATP-induced IL-1beta release (EC(50) = 617 microM) with IC(50) values of 75 and 3500 nM, respectively. The selective p38 mitogen-activated protein kinase (MAPK) inhibitor, 4-(4-fluorophenyl)-2-(4-hydroxyphenyl)-5-(4-pyridyl)-1H-imidazole (SB 202190), potently inhibited BzATP-induced pore formation (IC(50) = 75 nM) but did not alter P2X(7)-mediated calcium influx or IL-1beta release. SB 202190 and KN-62 also attenuated BzATP-mediated activation of phosphorylated p38 MAPK (pp38 MAPK). Two caspase inhibitors, YVAD (caspase 1) and DEVD (caspase 3), attenuated both BzATP-induced pore formation and IL-1beta release in a concentration-dependent fashion. Neither DEVD nor p38-MAPK inhibitors blocked cell membrane pore formation evoked by maitotoxin or by activation of human P2X(2a) receptors. These results indicate that P2X(7)R-mediated pore formation results from a coordinated cascade involving both the p38 MAPK and caspase pathways that is distinct from other cytolytic pore-forming mechanisms. In contrast, P2X(7)R-mediated IL-1beta release is dependent on caspase activity but not p38 MAPK. Taken together, these results support the hypothesis that downstream cellular signaling mechanisms, rather than channel dilation, mediate cytolytic pore formation after prolonged agonist activation, which underlies P2X(7) receptors.
ESTHER : Donnelly-Roberts_2004_J.Pharmacol.Exp.Ther_308_1053
PubMedSearch : Donnelly-Roberts_2004_J.Pharmacol.Exp.Ther_308_1053
PubMedID: 14634045

Title : A cell-based microarrayed compound screening format for identifying agonists of G-protein-coupled receptors - Gopalakrishnan_2003_Anal.Biochem_321_192
Author(s) : Gopalakrishnan SM , Moreland RB , Kofron JL , Helfrich RJ , Gubbins E , McGowen J , Masters JN , Donnelly-Roberts D , Brioni JD , Burns DJ , Warrior U
Ref : Analytical Biochemistry , 321 :192 , 2003
Abstract : The identification of agonist and antagonist leads for G-protein-coupled receptors (GPCRs) is of critical importance to the pharmaceutical and biotechnology industries. We report on the utilization of a novel, high-density, well-less screening platform known as microarrayed compound screening microARCS) that tests 8640 compounds in the footprint of a standard microtiter plate for the identification of novel agonists for a specific G-protein-coupled receptor. Although receptors coupled to the G alpha(q) protein can readily be assessed by fluorescence-based Ca(2+) release measurements, many GPCRs that are coupled to G alpha(s) or G alpha(i/o) proteins are not amenable to functional evaluation in such a high-throughput manner. In this study, the human dopamine D(4.4) receptor, which normally couples through the G alpha(i/o) protein to inhibit adenylate cyclase and to reduce levels of intracellular cAMP, was coupled to intracellular Ca(2+) release by stably coexpressing this receptor with a chimeric G(alpha qo5) protein in HEK-293 cells. In microARCS format, the cells expressing D(4.4) receptor and G alpha(qo5) protein were preloaded with fluo-4, cast into a 1% agarose gel, placed above the compound sheets, and imaged successively using a ViewLux charge-coupled device imaging system. Dopamine and other agonists evoked an increase in fluorescence response that appeared as bright spots in a time- and concentration-dependent manner. Utilizing this technology, a library of 260,000 compounds was rapidly screened and led to the identification of several novel agonists. These agonists were further characterized using a fluorometric imaging plate reader assay. Excellent confirmation rates coupled with enhanced efficiency and throughput enable microARCS to serve as an alternative platform for the screening and identification of novel GPCR agonists.
ESTHER : Gopalakrishnan_2003_Anal.Biochem_321_192
PubMedSearch : Gopalakrishnan_2003_Anal.Biochem_321_192
PubMedID: 14511684

Title : Reduced nicotinic receptor-mediated antinociception following in vivo antisense knock-down in rat - Bitner_2000_Brain.Res_871_66
Author(s) : Bitner RS , Nikkel AL , Curzon P , Donnelly-Roberts D , Puttfarcken PS , Namovic M , Jacobs IC , Meyer MD , Decker MW
Ref : Brain Research , 871 :66 , 2000
Abstract : Pharmacological activation of neuronal nicotinic acetylcholine receptors can produce non-opioid antinociception in rodents. However, multiple nAChR subtypes exist, the most abundant of which contain alpha4 and beta2 subunits. The purpose of the present study was to investigate the role of alpha4-containing nAChRs in mediating nicotinic antinociception using an in vivo antisense strategy. Both i.c.v. infusion and repeated bolus injections into the cerebral aqueduct of an antisense oligonucleotide against the alpha4 subunit significantly attenuated the antinociceptive effects of the nAChR agonist A-85380 in the paw withdrawal test of acute thermal pain. Rats treated with a scrambled oligonucleotide displayed a full antinociceptive response to A-85380, while discontinuing antisense treatment restored the antinociceptive effects of the nicotinic agonist. Double immunohistochemical labeling revealed near-complete overlap of expression of the serotonin marker tryptophan hydroxylase and the alpha4 nAChR subunit in the dorsal raphe nucleus. The expression of alpha4-containing nAChRs by serotonergic neurons in the dorsal raphe offered a means to address nonspecific alpha4 knock-down, i.e., oligonucleotide-induced neurotoxicity. Immunohistochemical detection of alpha4 expression was reduced by nearly 50% in the dorsal raphe of antisense-treated rats as compared to either saline or missense-treated controls. In contrast, the expression of tryptophan hydroxylase, as well as, the alpha7 nAChR subunit in antisense-infused rats was similar to that observed in saline- and missense-treated controls. The results of these studies suggest that alpha4-containing nAChRs, possibly expressed by serotonergic neurons, are involved in nicotinic-mediated analgesia. However, these data do not eliminate the possibility that other nicotinic subunit combinations may also play a role in antinociception produced by nAChR activation.
ESTHER : Bitner_2000_Brain.Res_871_66
PubMedSearch : Bitner_2000_Brain.Res_871_66
PubMedID: 10882784

Title : Structure-activity studies related to ABT-594, a potent nonopioid analgesic agent: effect of pyridine and azetidine ring substitutions on nicotinic acetylcholine receptor binding affinity and analgesic activity in mice - Holladay_1998_Bioorg.Med.Chem.Lett_8_2797
Author(s) : Holladay MW , Bai H , Li Y , Lin NH , Daanen JF , Ryther KB , Wasicak JT , Kincaid JF , He Y , Hettinger AM , Huang P , Anderson DJ , Bannon AW , Buckley MJ , Campbell JE , Donnelly-Roberts D , Gunther KL , Kim DJ , Kuntzweiler TA , Sullivan JP , Decker MW , Arneric SP
Ref : Bioorganic & Medicinal Chemistry Lett , 8 :2797 , 1998
Abstract : Analogs of A-98593 (1) and its enantiomer ABT-594 (2) with diverse substituents on the pyridine ring were prepared and tested for affinity to nicotinic acetylcholine receptor binding sites in rat brain and for analgesic activity in the mouse hot plate assay. Numerous types of modifications were consistent with high affinity for [3H]cytisine binding sites. By contrast, only selected modifications resulted in retention of analgesic potency in the same range as 1 and 2. Analogs of 2 with one or two methyl substituents at the 3-position of the azetidine ring also were prepared and found to be substantially less active in both assays.
ESTHER : Holladay_1998_Bioorg.Med.Chem.Lett_8_2797
PubMedSearch : Holladay_1998_Bioorg.Med.Chem.Lett_8_2797
PubMedID: 9873625

Title : Identification and initial structure-activity relationships of (R)-5-(2-azetidinylmethoxy)-2-chloropyridine (ABT-594), a potent, orally active, non-opiate analgesic agent acting via neuronal nicotinic acetylcholine receptors - Holladay_1998_J.Med.Chem_41_407
Author(s) : Holladay MW , Wasicak JT , Lin NH , He Y , Ryther KB , Bannon AW , Buckley MJ , Kim DJ , Decker MW , Anderson DJ , Campbell JE , Kuntzweiler TA , Donnelly-Roberts D , Piattoni-Kaplan M , Briggs CA , Williams M , Arneric SP
Ref : Journal of Medicinal Chemistry , 41 :407 , 1998
Abstract : New members of a previously reported series of 3-pyridyl ether compounds are disclosed as novel, potent analgesic agents acting through neuronal nicotinic acetylcholine receptors. Both (R)-2-chloro-5-(2-azetidinylmethoxy)pyridine (ABT-594, 5) and its S-enantiomer (4) show potent analgesic activity in the mouse hot-plate assay following either intraperitoneal (i.p.) or oral (p.o.) administration, as well as activity in the mouse abdominal constriction (writhing) assay, a model of persistent pain. Compared to the S-enantiomer and to the prototypical potent nicotinic analgesic agent (+/-)-epibatidine, 5 shows diminished activity in models of peripheral side effects. Structure-activity studies of analogues related to 4 and 5 suggest that the N-unsubstituted azetidine moiety and the 2-chloro substituent on the pyridine ring are important contributors to potent analgesic activity.
ESTHER : Holladay_1998_J.Med.Chem_41_407
PubMedSearch : Holladay_1998_J.Med.Chem_41_407
PubMedID: 9484491

Title : Broad-spectrum, non-opioid analgesic activity by selective modulation of neuronal nicotinic acetylcholine receptors - Bannon_1998_Science_279_77
Author(s) : Bannon AW , Decker MW , Holladay MW , Curzon P , Donnelly-Roberts D , Puttfarcken PS , Bitner RS , Diaz A , Dickenson AH , Porsolt RD , Williams M , Arneric SP
Ref : Science , 279 :77 , 1998
Abstract : Development of analgesic agents for the treatment of severe pain requires the identification of compounds that are devoid of opioid receptor liabilities. A potent (inhibition constant = 37 picomolar) neuronal nicotinic acetylcholine receptor (nAChR) ligand called ABT-594 was developed that has antinociceptive properties equal in efficacy to those of morphine across a series of diverse animal models of acute thermal, persistent chemical, and neuropathic pain states. These effects were blocked by the nAChR antagonist mecamylamine. In contrast to morphine, repeated treatment with ABT-594 did not appear to elicit opioid-like withdrawal or physical dependence. Thus, ABT-594 may be an analgesic that lacks the problems associated with opioid analgesia.
ESTHER : Bannon_1998_Science_279_77
PubMedSearch : Bannon_1998_Science_279_77
PubMedID: 9417028

Title : Synthesis and structure-activity relationships of pyridine-modified analogs of 3-[2-((S)-pyrrolidinyl)methoxy]pyridine, A-84543, a potent nicotinic acetylcholine receptor agonist - Lin_1998_Bioorg.Med.Chem.Lett_8_249
Author(s) : Lin NH , Gunn DE , Li Y , He Y , Bai H , Ryther KB , Kuntzweiler T , Donnelly-Roberts D , Anderson DJ , Campbell JE , Sullivan JP , Arneric SP , Holladay MW
Ref : Bioorganic & Medicinal Chemistry Lett , 8 :249 , 1998
Abstract : Analogs of 3-[2-((S)-pyrrolidinyl)methoxy]pyridine, (A-84543, 1) with 2-, 4-, 5-, and 6-substituents on the pyridine ring were synthesized. These analogs exhibited Ki values ranging from 0.15 to > 9,000 nM when tested in vitro for neuronal nicotinic acetylcholine receptor binding activity. Assessment of functional activity at subtypes of neuronal nicotinic acetylcholine receptors indicates that pyridine substitution can have a profound effect on efficacy at these subtypes, and several subtype-selective agonists and antagonists have been identified.
ESTHER : Lin_1998_Bioorg.Med.Chem.Lett_8_249
PubMedSearch : Lin_1998_Bioorg.Med.Chem.Lett_8_249
PubMedID: 9871663

Title : The role of neuronal nicotinic acetylcholine receptors in antinociception: effects of ABT-594 - Decker_1998_J.Physiol.Paris_92_221
Author(s) : Decker MW , Curzon P , Holladay MW , Nikkel AL , Bitner RS , Bannon AW , Donnelly-Roberts D , Puttfarcken PS , Kuntzweiler TA , Briggs CA , Williams M , Arneric SP
Ref : Journal de Physiologie (Paris) , 92 :221 , 1998
Abstract : ABT-594, a nicotinic acetylcholine receptor agonist, has antinociceptive effects in rat models of acute thermal, persistent chemical, and neuropathic pain. Direct injection of ABT-594 into the nucleus raphe magnus (NRM) is antinociceptive in a thermal threshold test and destruction of serotonergic neurons in the NRM attenuates the effect of systemic ABT-594. However, lidocaine-inactivation of the NRM prevents the antinociceptive effect of systemic (-)-nicotine but not that of systemic ABT-594.
ESTHER : Decker_1998_J.Physiol.Paris_92_221
PubMedSearch : Decker_1998_J.Physiol.Paris_92_221
PubMedID: 9789812

Title : ABT-594 [(R)-5-(2-azetidinylmethoxy)-2-chloropyridine]: a novel, orally effective analgesic acting via neuronal nicotinic acetylcholine receptors: I. In vitro characterization - Donnelly-Roberts_1998_J.Pharmacol.Exp.Ther_285_777
Author(s) : Donnelly-Roberts D , Puttfarcken PS , Kuntzweiler TA , Briggs CA , Anderson DJ , Campbell JE , Piattoni-Kaplan M , McKenna DG , Wasicak JT , Holladay MW , Williams M , Arneric SP
Ref : Journal of Pharmacology & Experimental Therapeutics , 285 :777 , 1998
Abstract : The discovery of (+/-)-epibatidine, a naturally occurring neuronal nicotinic acetylcholine receptor (nAChR) agonist with antinociceptive activity 200-fold more potent than that of morphine, has renewed interest in the potential role of nAChRs in pain processing. However, (+/-)-epibatidine has significant side-effect liabilities associated with potent activity at the ganglionic and neuromuscular junction nAChR subtypes which limit its potential as a clinical entity. ABT-594 [(R)-5-(2-azetidinylmethoxy)-2-chloropyridine] is a novel, potent cholinergic nAChR ligand with analgesic properties (see accompanying paper by Bannon et al., 1998b) that shows preferential selectivity for neuronal nAChRs and a consequently improved in vivo side-effect profile compared with (+/-)-epibatidine. ABT-594 is a potent inhibitor of the binding of [3H](-)-cytisine to alpha 4 beta 2 neuronal nAChRs (Ki = 37 pM, rat brain; Ki = 55 pM, transfected human receptor). At the alpha 1 beta 1 delta gamma neuromuscular nAChR labeled by [125I] alpha-bungarotoxin (alpha-Btx), ABT-594 has a Ki value of 10,000 nM resulting in a greater than 180,000-fold selectivity of the compound for the neuronal alpha 4 beta 2 nAChR. In contrast, (+/-)-epibatidine has Ki values of 70 pM and 2.7 nM at the alpha 4 beta 2 and alpha 1 beta 1 delta gamma nAChRs, respectively, giving a selectivity of only 38-fold. The S-enantiomer of ABT-594, A-98593 has activity at the neuronal alpha 4 beta 2 nAChR identical with ABT-594 (Ki = 34-39 pM), which demonstrates a lack of stereospecific binding similar to that reported previously for (+/-)-epibatidine. A similar lack of stereoselectivity is seen at the human alpha 7 receptor. However, A-98593 is 3-fold more potent at the neuromuscular nAChR (Ki = 3420 nM) and the brain alpha-Btx-sensitive nAChR (Ki = 4620 nM) than ABT-594. ABT-594 has weak affinity in binding assays for adrenoreceptor subtypes alpha-1B (Ki = 890 nM), alpha-2B (Ki = 597 nM) and alpha-2C (Ki = 342 nM), and it has negligible affinity (Ki > 1000 nM) for approximately 70 other receptors, enzyme and transporter binding sites. Functionally, ABT-594 is an agonist. At the transfected human alpha 4 beta 2 neuronal nAChR (K177 cells), with increased 86Rb+ efflux as a measure of cation efflux, ABT-594 had an EC50 value of 140 nM with an intrinsic activity (IA) compared with (-)-nicotine of 130%; at the nAChR subtype expressed in IMR-32 cells (sympathetic ganglion-like), an EC50 of 340 nM (IA = 126%); at the F11 dorsal root ganglion cell line (sensory ganglion-like), an EC50 of 1220 nM (IA = 71%); and via direct measurement of ion currents, an EC50 value of 56,000 nM (IA = 83%) at the human alpha 7 homooligimeric nAChR produced in oocytes. A-98593 is 2- to 3-fold more potent and displays approximately 50% greater intrinsic activity than ABT-594 in all four functional assays. In terms of potency, ABT-594 is 8- to 64-fold less active than (+/-)-epibatidine and also has less IA in these functional assays. ABT-594 (30 microM) inhibits the release of calcitonin gene-related peptide from C-fibers terminating in the dorsal horn of the spinal cord, an effect mediated via nAChRs. Pharmacologically, ABT-594 has an in vitro profile distinct from that of the prototypic nicotinic analgesic (+/-)-epibatidine, with the potential for substantially reduced side-effect liability and, as such, represents a potentially novel therapeutic approach to pain management.
ESTHER : Donnelly-Roberts_1998_J.Pharmacol.Exp.Ther_285_777
PubMedSearch : Donnelly-Roberts_1998_J.Pharmacol.Exp.Ther_285_777
PubMedID: 9580626

Title : Evidence for nicotinic receptors potentially modulating nociceptive transmission at the level of the primary sensory neuron: studies with F11 cells - Puttfarcken_1997_J.Neurochem_69_930
Author(s) : Puttfarcken PS , Manelli AM , Arneric SP , Donnelly-Roberts D
Ref : Journal of Neurochemistry , 69 :930 , 1997
Abstract : F11 cells are a dorsal root ganglion (DRG) cell line used to model the function of authentic type C, peptidergic, nociceptive neurons. The cellular events underlying the antinociceptive effects of (+/-)-epibatidine, a nicotinic acetylcholine receptor (nAChR) ligand that is 200-fold more potent than morphine, is unknown. The present study investigated the ability of cholinergic channel activators (ChCAs) to effect nAChR-gated ion flux and modulate the release of substance P (SP), a neuropeptide identified to play a critical role in nociception. The prototypical agonists (-)-nicotine and (-)-cytisine, the ganglionic stimulant 1,1-dimethyl-4-phenylpiperazinium, the novel ChCA ABT-418 [(S)-3-methyl-5-(-1-methyl-2-pyrrolidinyl)isoxazole], and (+/-)-epibatidine evoked a concentration-dependent stimulation of rubidium (86Rb+) efflux with EC50 values of 14.2 +/- 1.6, 63.4 +/- 24, 3.8 +/- 2.0, 29.8 +/- 2.6, and 0.019 +/- 0.001 microM as well as maximal intrinsic activities of 100, 97, 69, 75, and 102%, respectively. The noncompetitive nAChR antagonist mecamylamine potently antagonized (-)-nicotine-evoked ion flux, whereas the competitive antagonist dihydro-beta-erythroidine was a weak antagonist, giving support to an alpha3beta4 nAChR subtype. In addition, concentrations of (+/-)-epibatidine, similar to those necessary to induce maximal 86Rb+ efflux, evoked spontaneous release of SP from these cells, which was blocked by mecamylamine. Furthermore, prolonged exposure to (+/-)-epibatidine desensitized the functional response of the nAChR in this cell line (IC50 = 12 +/- 9 nM). These findings in F11 cells provide a model to investigate the role nAChRs play in modulating DRG cell function, and may lead to insights into the role these receptors have in modulating nociceptive transmission.
ESTHER : Puttfarcken_1997_J.Neurochem_69_930
PubMedSearch : Puttfarcken_1997_J.Neurochem_69_930
PubMedID: 9282914

Title : ABT-089 [2-methyl-3-(2-(S)-pyrrolidinylmethoxy)pyridine]: I. A potent and selective cholinergic channel modulator with neuroprotective properties - Sullivan_1997_J.Pharmacol.Exp.Ther_283_235
Author(s) : Sullivan JP , Donnelly-Roberts D , Briggs CA , Anderson DJ , Gopalakrishnan M , Xue IC , Piattoni-Kaplan M , Molinari E , Campbell JE , McKenna DG , Gunn DE , Lin NH , Ryther KB , He Y , Holladay MW , Wonnacott S , Williams M , Arneric SP
Ref : Journal of Pharmacology & Experimental Therapeutics , 283 :235 , 1997
Abstract : Accumulating preclinical and clinical evidence data suggests that compounds that selectively activate neuronal nicotinic acetylcholine receptor (nAChR) subtypes may have therapeutic utility for the treatment of several neurological disorders. In the present study, the in vitro pharmacological properties of the novel cholinergic channel modulator ABT-089 [2-methyl-3-(2-(S)-pyrrolidinylmethoxy)pyridine], are described. In radioligand binding studies, ABT-089 was shown to display selectivity toward the high-affinity (-)-cytisine binding site present on the alpha4beta2 nAChR subtype (Ki = 16 nM) relative to the [125I]alpha-bungarotoxin binding site present on the alpha7 (Ki > or = 10,000 nM) and alpha1beta1deltagamma (Ki > 1000 nM) nAChR subtypes. In cation flux and channel current studies, ABT-089 displayed a more complex profile than (-)-nicotine having agonist, partial agonist and inhibitory activities depending on the nAChR subtype with which it interacts. ABT-089 differentially stimulated neurotransmitter release. The compound displayed a similar potency and efficacy to (-)-nicotine to facilitate ACh release (ABT-089, EC50 = 3 microM; (-)-nicotine, EC50 = 1 microM), but was markedly less potent and less efficacious than (-)-nicotine to stimulate dopamine release (ABT-089, EC50 = 1.1 microM; (-)-nicotine, EC50 = 0.04 microM). Additionally, ABT-089 was neuroprotective against the excitotoxic insults elicited by exposure to glutamate in both rat cortical cell cultures (EC50 = 10 +/- 3 microM) and differentiated human IMR32 cells (EC50 = 3 +/- 2 microM). The differential full agonist/partial agonist profile of ABT-089, as compared with (-)-nicotine and ABT-418, illustrates the complexity of nAChR activation and the potential to target responses at subclasses of the neuronal and peripheral receptors.
ESTHER : Sullivan_1997_J.Pharmacol.Exp.Ther_283_235
PubMedSearch : Sullivan_1997_J.Pharmacol.Exp.Ther_283_235
PubMedID: 9336329

Title : Functional characterization of the novel neuronal nicotinic acetylcholine receptor ligand GTS-21 in vitro and in vivo - Briggs_1997_Pharmacol.Biochem.Behav_57_231
Author(s) : Briggs CA , Anderson DJ , Brioni JD , Buccafusco JJ , Buckley MJ , Campbell JE , Decker MW , Donnelly-Roberts D , Elliott RL , Gopalakrishnan M , Holladay MW , Hui YH , Jackson WJ , Kim DJ , Marsh KC , O'Neill A , Prendergast MA , Ryther KB , Sullivan JP , Arneric SP
Ref : Pharmacol Biochem Behav , 57 :231 , 1997
Abstract : (2.4)-Dimethoxybenzylidene anabaseine dihydrochloride (GTS-21), a compound that interacts with rat neuronal nicotinic acetylcholine receptors (nAChRs), was evaluated using human recombinant nAChRs in vitro and various pharmacokinetic and behavioral models in rodents, dogs and monkeys. GTS-21 bound to human alpha 4 beta 2 nAChR (K1-20 nM) 100-fold more potently than to human alpha 7 nAChR, and was 18- and 2-fold less potent than (-)-nicotine at human alpha 4 beta 2 and alpha 7 nAChR, respectively. Functionally. GTS-21 stimulated [5H]dopamine release from rat striatal slices with an EC50 of 10 +/- 2 microM (250-fold less potent and 70% as efficacious as (-)-nicotine), an effect blocked by the nAChR antagonist dihydro-beta-erythroidine. However, GTS-21 did not stimulate human alpha 4 beta 2 nor human ganglionic nAChRs significantly. In vivo, GTS-21 had no adverse effect on dog blood pressure (< or = 2.5 micromol/kg i.v. bolus infusion), in marked contrast with (-)-nicotine, GTS-21 (-62 micromol/kg.s.e.) also did not cross-discriminate significantly with (-)-nicotine in rats and did not reduce temperature or locomotion in mice. Neither was it active in the elevated plus maze anxiety model (0.19-6.2 micromol/kg.IP) in normal mice. However, GTS-21 did improve learning performance of monkeys in the delayed matching-to-sample task (32-130 nmol/kg.i.m.).
ESTHER : Briggs_1997_Pharmacol.Biochem.Behav_57_231
PubMedSearch : Briggs_1997_Pharmacol.Biochem.Behav_57_231
PubMedID: 9164577

Title : Structure-activity studies on 2-methyl-3-(2(S)-pyrrolidinylmethoxy) pyridine (ABT-089): an orally bioavailable 3-pyridyl ether nicotinic acetylcholine receptor ligand with cognition-enhancing properties - Lin_1997_J.Med.Chem_40_385
Author(s) : Lin NH , Gunn DE , Ryther KB , Garvey DS , Donnelly-Roberts D , Decker MW , Brioni JD , Buckley MJ , Rodrigues AD , Marsh KG , Anderson DJ , Buccafusco JJ , Prendergast MA , Sullivan JP , Williams M , Arneric SP , Holladay MW
Ref : Journal of Medicinal Chemistry , 40 :385 , 1997
Abstract : 2-Methyl-3-(2(S)-pyrrolidinylmethoxy)pyridine, ABT-089 (S-4), a member of the 3-pyridyl ether class of nicotinic acetylcholine receptor (nAChR) ligands, shows positive effects in rodent and primate models of cognitive enhancement and a rodent model of anxiolytic activity and possesses a reduced propensity to activate peripheral ganglionic type receptors. The profiles of S-4, its N-methyl analogue, and the corresponding enantiomers across several measures of cholinergic channel function in vitro and in vivo are presented, together with in vitro metabolism and in vivo bioavailability data. On the basis of its biological activities and favorable oral bioavailability, S-4 is an attractive candidate for further evaluation as a treatment for cognitive disorders.
ESTHER : Lin_1997_J.Med.Chem_40_385
PubMedSearch : Lin_1997_J.Med.Chem_40_385
PubMedID: 9022806

Title : Stable expression, pharmacologic properties and regulation of the human neuronal nicotinic acetylcholine alpha 4 beta 2 receptor - Gopalakrishnan_1996_J.Pharmacol.Exp.Ther_276_289
Author(s) : Gopalakrishnan M , Monteggia LM , Anderson DJ , Molinari EJ , Piattoni-Kaplan M , Donnelly-Roberts D , Arneric SP , Sullivan JP
Ref : Journal of Pharmacology & Experimental Therapeutics , 276 :289 , 1996
Abstract : (-)-Nicotine, the prototypical agonist for neuronal nicotinic acetylcholine receptors (nAChR) has been shown to bind with high affinity to the rodent and avian alpha 4 beta 2 nAChR subtype. This subtype may represent a primary molecular target for some of the beneficial central nervous system effects i.e., cognitive enhancement, anxiolysis, analgesia, neuroprotection, of (-)-nicotine and related ligands. However, a detailed study of the human alpha 4 beta 2 subunit combination has not yet been reported. In this study, we stably coexpressed the human neuronal alpha 4 and beta 2 nAChR subunits in human embryonic kidney (HEK) 293 cells and studied its pharmacological and regulatory properties. [3H]Cytisine bound to stably transfected cells with high affinity (KD value, 0.2 +/- 0.04 nM) and with a Bmax value of 1359 +/- 91 fmol/mg protein. A good correlation (r = 0.98) was observed between binding affinities in transfected cells and in native neuronal preparations for a series of nAChR ligands. 86Rb+ efflux studies showed that stably transfected cells express functional ion channels that are sensitive to blockade by dihydro-beta-erythroidine. (+/-)-Epibatidine, (-)-nicotine, 1,1-dimethyl-4-phenylpiperazinium, (S)-3-methyl-5-(1-methyl-2-pyrrolidinyl)isoxazole (ABT-418), acetylcholine and (-)-cytisine stimulated 86Rb+ efflux with EC50 values of 0.02, 3.9, 2.5, 10, 44 and 38 microM, respectively. Treatment of transfected cells with (-)-nicotine for 7 days led to a significant increase in the density of [3H](-)-cytisine binding sites (EC50 = 0.56 microM) and a significant enhancement in the sensitivity of ACh. Specific binding or (-)-nicotine-evoked cation efflux was not detected in untransfected cells. Analysis of total cellular RNA from transfected, but not untransfected cells, showed the expected fragment sizes corresponding to the human alpha 4 and beta 2 subunit mRNA. These results demonstrate that stable expression of the human alpha 4 beta 2 nAChR subunit combination can give rise to functional ion channels that bind [3H](-)-cytisine with high affinity, exhibit homologous regulation and evoke agonist-induced cation flux with pharmacological properties consistent with native neuronal alpha 4 beta 2 nAChR.
ESTHER : Gopalakrishnan_1996_J.Pharmacol.Exp.Ther_276_289
PubMedSearch : Gopalakrishnan_1996_J.Pharmacol.Exp.Ther_276_289
PubMedID: 8558445

Title : Novel 3-Pyridyl ethers with subnanomolar affinity for central neuronal nicotinic acetylcholine receptors - Abreo_1996_J.Med.Chem_39_817
Author(s) : Abreo MA , Lin NH , Garvey DS , Gunn DE , Hettinger AM , Wasicak JT , Pavlik PA , Martin YC , Donnelly-Roberts D , Anderson DJ , Sullivan JP , Williams M , Arneric SP , Holladay MW
Ref : Journal of Medicinal Chemistry , 39 :817 , 1996
Abstract : Recent evidence indicating the therapeutic potential of cholinergic channel modulators for the treatment of central nervous system (CNS) disorders as well as the diversity of brain neuronal nicotine acetylcholine receptors (nAChRs) have suggested an opportunity to develop subtype-selective nAChR ligands for the treatment of specific CNS disorders with reduced side effect liabilities. We report a novel series of 3-pyridyl ether compounds which possess subnanomolar affinity for brain nAChRs and differentially activate subtypes of neuronal nAChRs. The synthesis and structure-activity relationships for the leading members of the series are described, including A-85380 (4a), which possesses ca.50 pM affinity for rat brain [(3)H]-(-)-cytisine binding sites and 163% efficacy compared to nicotine to stimulate ion flux at human alpha4beta2 nAChR subtype, and A-84543 (2a), which exhibits 84-fold selectivity to stimulate ion flux at human alpha4beta2 nAchR subtype compared to human ganglionic type nAChRs. Computational studies indicate that a reasonable superposition of a low energy conformer of 4A with (S)-nicotine and (-)-epibatidine can be achieved.
ESTHER : Abreo_1996_J.Med.Chem_39_817
PubMedSearch : Abreo_1996_J.Med.Chem_39_817
PubMedID: 8632405

Title : A-85380 [3-(2(S)-azetidinylmethoxy) pyridine]: in vitro pharmacological properties of a novel, high affinity alpha 4 beta 2 nicotinic acetylcholine receptor ligand - Sullivan_1996_Neuropharmacol_35_725
Author(s) : Sullivan JP , Donnelly-Roberts D , Briggs CA , Anderson DJ , Gopalakrishnan M , Piattoni-Kaplan M , Campbell JE , McKenna DG , Molinari E , Hettinger AM , Garvey DS , Wasicak JT , Holladay MW , Williams M , Arneric SP
Ref : Neuropharmacology , 35 :725 , 1996
Abstract : The in vitro pharmacological properties of a novel cholinergic channel ligand, A-85380 [3-(2(S)-azetidinylmethoxy)pyridine], were examined using tissue preparations that express different putative nAChR subtypes. In radioligand binding studies, A-85380 is shown to be a potent and selective ligand for the human alpha 4 beta 2 nAChR subtype (Ki = 0.05 + 0.01 nM) relative to the human alpha 7 (Ki = 148 +/- 13 nM) and the muscle alpha 1 beta 1 dg subtype expressed in Torpedo electroplax (Ki = 314 +/- 12 nM). The R-enantiomer of A-85380, A-159470, displays little enantioselectivity towards the alpha 4 beta 2 and alpha 1 beta 1 delta gamma subtypes but does not display 12-fold enantioselectivity towards the alpha 7 subtype (Ki = 1275 +/- 199 nM). (+)- and(-)-Epibatidine display similar potencies at the human human alpha 4 beta 2 (Ki = 0.04 +/- 0.02 nM and 0.07 +/- 0.02 nM, respectively), human alpha 7 (Ki = 16 +/- 2 nM and 22 +/- 3 nM, respectively) and muscle alpha 1 beta 1 delta gamma g (Ki = 2.5 +/- 0.9 nM and 5.7 +/- 1.0 nM, respectively) nAChRs. Functionally, A-85380 is a potent activator of cation efflux through the human alpha 4 beta 2 (EC50 = 0.7 +/- 0.1 microM) and ganglionic (EC50 = 0.8 +/- 0.09 microM) subtypes, effects that are attenuated by pretreatment with mecamylamine (10 microM). Further, A-85380 can activate (EC50 = 8.9 +/- 1.9 microM) currents through channels formed by injection of the human alpha 7 subunit into Xenopus oocytes, effects that are attenuated by pretreatment with the alpha 7 nAChR antagonist, methyllycaconitine (10 nM). In all cases, A-85380 is more potent than (-)-nicotine but less potent than (+/-)-epibatidine. In neurotransmitter release studies, A-85380 stimulates the release of dopamine with an EC 50 value of 0.003 +/- 0.001 microM which is equipotent to (+/-)-epibatidine, and 20-fold more potent than (-)-nicotine (EC50 = 0.04 +/- 0.009 microM). Thus, A-85380 displays a profile of robust activation of a number of nAChR subtypes with substantially less affinity for [125I] alpha-BgT sites than [3H](-)-cytisine sites, suggesting that it may serve as a more selective pharmacologic probe for the alpha 4 beta 2 subtype relative to the alpha 7 and alpha 1 beta 1 delta g nAChRs than (+/-)-epibatidine.
ESTHER : Sullivan_1996_Neuropharmacol_35_725
PubMedSearch : Sullivan_1996_Neuropharmacol_35_725
PubMedID: 8887981

Title : In vitro neuroprotective properties of the novel cholinergic channel activator (ChCA), ABT-418 - Donnelly-Roberts_1996_Brain.Res_719_36
Author(s) : Donnelly-Roberts D , Xue IC , Arneric SP , Sullivan JP
Ref : Brain Research , 719 :36 , 1996
Abstract : Recent literature has shown that compounds interacting with neuronal nicotinic acetylcholine receptors (nAChRs) have the potential to be neuroprotective both in vitro and in vivo. ABT-418 is a novel ChCA that selectively stimulates discrete subtypes of the nAChRs and exhibits cognitive enhancing activity. In the present study, the neuroprotective effects of ABT-418 and (-)-nicotine, as measured by the release of lactate dehydrogenase (LDH) into the media, were investigated in a glutamate (Glu)-induced cytotoxicity assay using either primary rat cortical neurons or a human differentiated cell line, IMR 32. The neuroprotection elicited by ABT-418 and (-)-nicotine is both time and concentration dependent with an optimal concentration of 10 microM and an optimal pretreatment time of 2 h. ABT-418 remained neuroprotective and not cytotoxic to rat cortical cells following subacute exposure for 7 days. Protection appears to be mediated via an interaction with nAChRs, possibly the alpha 7 subtype, since the neuroprotection was prevented by alpha-bungaratoxin (alpha-Bgt) and methyllycaconitine (MLA), both selective alpha 7 antagonists. Removal of extracellular Ca2+ prevented the neuroprotective effects of ABT-418 and (-)-nicotine, consistent with the known ability of alpha 7 nAChRs to modulate calcium dynamics. These data support the idea that ABT-418 not only enhances cognition, but may possibly slow the progression of the neurodegenerative process.
ESTHER : Donnelly-Roberts_1996_Brain.Res_719_36
PubMedSearch : Donnelly-Roberts_1996_Brain.Res_719_36
PubMedID: 8782861

Title : Stable expression and pharmacological properties of the human alpha 7 nicotinic acetylcholine receptor - Gopalakrishnan_1995_Eur.J.Pharmacol_290_237
Author(s) : Gopalakrishnan M , Buisson B , Touma E , Giordano T , Campbell JE , Hu IC , Donnelly-Roberts D , Arneric SP , Bertrand D , Sullivan JP
Ref : European Journal of Pharmacology , 290 :237 , 1995
Abstract : The alpha 7 neuronal nicotinic acetylcholine receptor subtype forms a Ca(2+)-permeable homooligomeric ion channel sensitive to alpha-bungarotoxin in Xenopus oocytes. In this study, we have stably and functionally expressed the human alpha 7 cDNA in a mammalian cell line, HEK-293 and examined its pharmacologic properties. [125I] alpha-Bungarotoxin bound to transfected cells with a Kd value of 0.7 nM and a Bmax value of 973 pmoL/mg protein. No specific binding was detected in untransfected cells. Specific binding could be displaced by unlabeled alpha-bungarotoxin (Ki = 0.5 nM) and an excellent correlation was observed between binding affinities of a series of nicotinic cholinergic ligands in transfected cells and those in the human neuroblastoma IMR-32 cell line. Additionally, cell surface expression of alpha 7 receptors was detected by fluorescein isothiocyanate-conjugated alpha-bungarotoxin in transfected cells. Whole cell currents sensitive to blockade by alpha-bungarotoxin, and with fast kinetics of activation and inactivation, were recorded from transfected cells upon rapid application of (-)-nicotine or acetylcholine with EC50 values of 49 microM and 155 microM respectively. We conclude that the human alpha 7 subunit when expressed alone can form functional ion channels and that the stably transfected HEK-293 cell line serves as a unique system for studying human alpha 7 nicotinic receptor function and regulation, and for examining ligand interactions.
ESTHER : Gopalakrishnan_1995_Eur.J.Pharmacol_290_237
PubMedSearch : Gopalakrishnan_1995_Eur.J.Pharmacol_290_237
PubMedID: 7589218

Title : Cholinergic channel activators: novel opportunities for the treatment of CNS disorders - Sullivan_1995_Proc.West.Pharmacol.Soc_38_127
Author(s) : Sullivan JP , Decker MW , Donnelly-Roberts D , Brioni JD , Bannon AW , Holladay MW , Anderson DJ , Briggs CA , Williams M , Arneric SP
Ref : Proc West Pharmacol Soc , 38 :127 , 1995
Abstract : Negative connotations associated with the use of (-)-nicotine has limited medicinal chemistry research in the area of nAChRs [5]. However, recent evidence suggests that a diversity of nAChR subunits exist, that each subtype may be involved in mediating specific neurochemical/behaviors, and that these subtypes have a defined pharmacology that may be selectively targeted [1]. (+/-)-Epibatidine, GTS-21 and ABT-418 differentially interact with nAChR subtypes to elicit a diversity of behavioral effects including analgesia, neuroprotection and cognitive enhancement. These agents therefore represent important new pharmacological probes to dissect the nAChR subtype(s) mediating specific pharmacological responses to nAChR activation.
ESTHER : Sullivan_1995_Proc.West.Pharmacol.Soc_38_127
PubMedSearch : Sullivan_1995_Proc.West.Pharmacol.Soc_38_127
PubMedID: 7480004

Title : Potential treatment of Alzheimer disease using cholinergic channel activators (ChCAs) with cognitive enhancement, anxiolytic-like, and cytoprotective properties - Arneric_1995_Alzheimer.Dis.Assoc.Disord_9 Suppl 2_50
Author(s) : Arneric SP , Sullivan JP , Decker MW , Brioni JD , Bannon AW , Briggs CA , Donnelly-Roberts D , Radek RJ , Marsh KC , Kyncl J , Williams M , Buccafusco JJ
Ref : Alzheimer Disease & Associated Disorders , 9 Suppl 2 :50 , 1995
Abstract : Compounds that activate neuronal nicotinic acetylcholine receptors (nAChRs) may have potential benefit in the treatment of dementia, especially Alzheimer disease (AD). This article summarizes the preclinical pharmacology of ABT-418 [(S)-3-methyl-5-(1-methyl-2-pyrrolidinyl) isoxazole], a novel analog of (-)-nicotine that is being clinically evaluated for the treatment of AD. ABT-418 is a cholinergic channel activator (ChCA) with cognitive enhancement and anxiolytic-like activity possessing a substantially reduced side-effect profile compared to (-)-nicotine [Arneric SP, Sullivan JP, Briggs CA, et al. (S)-3-Methyl-5-(1-Methyl-2-Pyrrolidinyl)Isoxazole (ABT-418): A novel cholinergic ligand with cognition enhancing and anxiolytic activity. I. In vitro activity. J Pharmacol Exp Ther 1994 ;270:310-318; Decker MW, Brioni JD, Sullivan JP, et al. (S)-3-Methyl-5-( 1-Methyl-2-Pyrrolidinyl)Isoxazole (ABT-418): A novel cholinergic ligand with cognition-enhancing and anxiolytic activities: II. In vivo characterization. J Pharmacol Exp Ther 1994a;270:319-328; Decker MW, Curzon P, B rioni JD, Arne ric SP. Effects of ABT-418, a novel cholinergic channel ligand, on place learning in septal-lesioned rats. Eur J Pharmacol 1994;261:217-222; Garvey DS, Wasicak JT, Decker MW, et al. Novel isoxazoles which interact with brain cholinergic channel receptors have intrinsic cognitive enhancing and anxiolytic activities. J Med Chem 1994;37:1055-1059]. ABT-418 may be the first agonist of nAChRs to be developed and evaluated specifically for the treatment of AD. Some brief speculation will be given on the potential benefits that this or other ChCAs may have in treating neurodegenerative disorders as compared with (-)-nicotine, and how this differs from other potential treatment approaches.
ESTHER : Arneric_1995_Alzheimer.Dis.Assoc.Disord_9 Suppl 2_50
PubMedSearch : Arneric_1995_Alzheimer.Dis.Assoc.Disord_9 Suppl 2_50
PubMedID: 8534424

Title : Erysodine, a competitive antagonist at neuronal nicotinic acetylcholine receptors - Decker_1995_Eur.J.Pharmacol_280_79
Author(s) : Decker MW , Anderson DJ , Brioni JD , Donnelly-Roberts D , Kang CH , O'Neill AB , Piattoni-Kaplan M , Swanson S , Sullivan JP
Ref : European Journal of Pharmacology , 280 :79 , 1995
Abstract : Erysodine, an erythrina alkaloid related to dihydro-beta-erythroidine, was found to be a more potent inhibitor of [3H]cytisine binding at neuronal nicotinic acetylcholine receptors but a less potent inhibitor of [125I]alpha-bungarotoxin binding at muscle-type nicotinic acetylcholine receptors than dihydro-beta-erythroidine. Erysodine was a competitive, reversible antagonist of (-)-nicotine-induced dopamine release from striatal slices and inhibited (-)-nicotine-induced 86Rb+ efflux from IMR-32 cells. Erysodine was equipotent with dihydro-beta-erythroidine in the dopamine release assay but 10-fold more potent in the 86Rb+ efflux assay, suggesting differential subtype selectivity for these two antagonists. Erysodine, systemically administered to mice, entered the brain and significantly attentuated nicotine's hypothermic effects and its anxiolytic-like effects in the elevated plus-maze test. There was greater separation between antagonist and toxic doses for erysodine than for dihydro-beta-erythroidine, perhaps because of erysodine's greater selectivity for neuronal receptors. In rats, erysodine prevented both the early developing decrease and the late-developing increase in locomotor activity produced by (-)-nicotine. The potent and competitive nature of erysodine's antagonism together with its ability to enter the brain after systemic administration suggest that erysodine may be a useful tool in characterizing neuronal nicotinic acetylcholine receptors.
ESTHER : Decker_1995_Eur.J.Pharmacol_280_79
PubMedSearch : Decker_1995_Eur.J.Pharmacol_280_79
PubMedID: 7498257

Title : Functional modulation of human ganglionic-like neuronal nicotinic acetylcholine receptors (nAChRs) by L-type calcium channel antagonists - Donnelly-Roberts_1995_Biochem.Biophys.Res.Commun_213_657
Author(s) : Donnelly-Roberts D , Arneric SP , Sullivan JP
Ref : Biochemical & Biophysical Research Communications , 213 :657 , 1995
Abstract : Recent studies suggest that the neuronal nicotinic acetylcholine receptors present on chromaffin cells contain a 1,4-dihydropyridine-sensitive site whose occupation blocks membrane depolarization (1). In the present study, several L-type Ca2+ channel blockers inhibited the activation of the nAChRs present in the human neuroblastoma cell line, IMR 32, in a dose-dependent manner with IC50 values ranging from 0.8-3 microM. In contrast, omega-Conotoxin GVIA and omega-Agatoxin IVA had no effect up to 100 microM. Furthermore, the inorganic channel blocker, cadmium, had no effect either alone or on the modulatory role of the L-type antagonists, suggesting that the effects of these agents on nAChRs are not mediated via an interaction with calcium channels but possibly via a direct interaction with the nAChR ionophore.
ESTHER : Donnelly-Roberts_1995_Biochem.Biophys.Res.Commun_213_657
PubMedSearch : Donnelly-Roberts_1995_Biochem.Biophys.Res.Commun_213_657
PubMedID: 7544126

Title : (+\/-)-Epibatidine elicits a diversity of in vitro and in vivo effects mediated by nicotinic acetylcholine receptors - Sullivan_1994_J.Pharmacol.Exp.Ther_271_624
Author(s) : Sullivan JP , Decker MW , Brioni JD , Donnelly-Roberts D , Anderson DJ , Bannon AW , Kang CH , Adams P , Piattoni-Kaplan M , Buckley MJ
Ref : Journal of Pharmacology & Experimental Therapeutics , 271 :624 , 1994
Abstract : (+/-)-Epibatidine, exo-2-(6-chloro-3-pyridyl)-7-azabicyclo-[2.2.1] heptane, is a novel, potent analgesic agent that acts through nicotinic acetylcholine receptor (nAChR) mechanisms. This study sought to establish whether (+/-)-epibatidine, like (-)-nicotine, also displays a wide diversity of behavioral responses that are known to be elicited by nAChR activation or whether it demonstrates subtype selectivity for its interactions with nAChRs.(+/-)-Epibatidine displaced [3H](-)-cytisine binding to the alpha 4 beta 2 nAChR subtype in rat brain membranes with high affinity (Ki, 43 pM). The compound was approximately 5000-fold less potent (Ki = 230nM) in the displacement of [125I] alpha-bungarotoxin binding from the alpha-bungarotoxin-sensitive nAChR subtype present in rat brain but was a potent inhibitor (Ki, 2.7 nM) of [125I] alpha-bungarotoxin binding to the nAChR subtype in Torpedo electroplax, which is similar to that present in the neuromuscular junction. Functionally, (+/-)-epibatidine enhanced 86Rb+ flux in IMR 32 cells with an EC50 value of 7 nM. It was some 3000-fold more potent than (-)-nicotine (EC50 value, 21,000 nM) and was approximately 150-fold more potent (EC50 value, 0.4 nM) than (-)-nicotine (EC50 value = 60 nM) in increasing [3H]dopamine release from rat striatal slices. Remarkably, (+/-)-epibatidine was 40% to 50% more efficacious than (-)-nicotine in both functional assays. Both functional effects were blocked by the nAChR channel blocker, mecamylamine (100 microM). (+/-)-Epibatidine was 300 to 1000 times more potent than (-)-nicotine in the reduction of body temperature and locomotor activity in mice.(ABSTRACT TRUNCATED AT 250 WORDS)
ESTHER : Sullivan_1994_J.Pharmacol.Exp.Ther_271_624
PubMedSearch : Sullivan_1994_J.Pharmacol.Exp.Ther_271_624
PubMedID: 7965777

Title : (S)-3-methyl-5-(1-methyl-2-pyrrolidinyl) isoxazole (ABT 418): a novel cholinergic ligand with cognition-enhancing and anxiolytic activities: I. In vitro characterization - Arneric_1994_J.Pharmacol.Exp.Ther_270_310
Author(s) : Arneric SP , Sullivan JP , Briggs CA , Donnelly-Roberts D , Anderson DJ , Raszkiewicz JL , Hughes ML , Cadman ED , Adams P , Garvey DS
Ref : Journal of Pharmacology & Experimental Therapeutics , 270 :310 , 1994
Abstract : A diversity of nicotinic acetylcholine receptor (nAChR) subtypes has been identified in mammalian brain using recombinant DNA technology. Alterations in the activity of these acetylcholinegated ion channels have been implicated in a number of central nervous system disorders including Alzheimer's disease (AD). The potential therapeutic usefulness of (-)-nicotine [(S)-3-(1-methyl-2-pyrrolidinyl) pyridine], the prototypic agonist at nAChRs, is severely limited by side effects that are the result of activation of both cholinergic and noncholinergic pathways in the central and peripheral nervous systems. This study sought to determine the in vitro selectivity of (S)-3-methyl-5-(1methyl-2-pyrrolidinyl)isoxazole (ABT 418), a novel analog of (-)-nicotine in which the pyridine ring was replaced with an isoxazole bioisotere, to activate nAChRs. ABT 418 was a potent inhibitor of [3H]-cytisine binding to nAChR in rat brain (Ki = 3 nM) but was inactive (Ki > 10,000 nM) in 37 other receptor/neurotransmitter-uptake/enzyme/transduction system binding assays, including those for alpha-bungarotoxin, muscarinic and 5-hydroxytryptamine3 receptors. In PC12 cells, patch-clamp studies indicated that ABT 418 was an agonist with an EC50 value of 209 microM, a potency to activate cholinergic channel currents some 4-fold less than that of (-)-nicotine (52 microM). Channel current responses elicited by ABT 418 were prevented by the cholinergic channel blocker, mecamylamine. ABT 418 was also approximately 10-fold less potent (EC50 value = 380 nM) than (-)-nicotine (40 nM) in increasing [3H]-dopamine release from rat striatal slices, an effect that was blocked by the nAChR antagonist, dihydro-beta-erythroidine (10 microM).2+ In contrast, ABT 418 appeared equipotent with (-)-nicotine in enhancing 86Rb+ flux from mouse thalamic synaptosomes. ABT 418 demonstrated an in vitro pharmacological profile of cholinergic channel activation that was robust at some nAChR, but not others. The reasons for this are unclear. However, a nAChR subtype selectivity may account for the in vitro potency differences of ABT 418 on various neurotransmitter systems, and the substantial separation between the cognitive enhancement/anxiolytic benefits, and the reduced central nervous system side-effect liabilities seen in vivo. ABT 418 represents the first neuronal nAChR ligand that differentiates the toxicities/liabilities and other negative aspects normally associated with liabilities and other negative aspects normally associated with (-)-nicotine from the potential pharmacological benefits of selective cholinergic channel activation.
ESTHER : Arneric_1994_J.Pharmacol.Exp.Ther_270_310
PubMedSearch : Arneric_1994_J.Pharmacol.Exp.Ther_270_310
PubMedID: 7518514

Title : Pathogenesis of hyperacute experimental autoimmune myasthenia gravis. Acetylcholine receptor\/cholinergic site\/receptor function\/autoimmunity - Mihovilovic_1994_J.Immunol_152_5997
Author(s) : Mihovilovic M , Donnelly-Roberts D , Richman DP , Martinez-Carrion M
Ref : J Immunol , 152 :5997 , 1994
Abstract : Three mAbs, mAbs 249E, 370, and 383C, directed against the alpha-bungarotoxin (alpha BgTx) binding site of the acetylcholine receptor (AChR) induce a hyperacute form of experimental autoimmune myasthenia gravis (EAMG), characterized by death within hours of mAb injection. To analyze the mechanisms of this effect, purified AChR-mAb complexes were investigated for their ability to bind the cholinergic agonist carbamoylcholine and to undergo agonist-induced activation of the cholinergic ionophore. The three mAbs inhibited carbamylcholine binding, and, conversely, their binding to AChR was inhibited by carbamylcholine. All three completely inhibited carbamylcholine-induced T1+ influxes to AChR-rich vesicles. These data indicate that the severe hyperacute EAMG induced by these mAbs results from blockage of AChR function and that the role of such potent Abs (even if present in small amounts) in the pathogenesis of human myasthenia gravis deserves further investigation.
ESTHER : Mihovilovic_1994_J.Immunol_152_5997
PubMedSearch : Mihovilovic_1994_J.Immunol_152_5997
PubMedID: 8207224

Title : Effects of mutations of Torpedo acetylcholine receptor alpha 1 subunit residues 184-200 on alpha-bungarotoxin binding in a recombinant fusion protein - Chaturvedi_1993_Biochemistry_32_9570
Author(s) : Chaturvedi V , Donnelly-Roberts D , Lentz TL
Ref : Biochemistry , 32 :9570 , 1993
Abstract : Residues between positions 184 and 200 of the Torpedo acetylcholine receptor alpha 1 subunit were changed by oligonucleotide-directed mutagenesis in a recombinant fusion protein containing residues 166-211. Amino acids were substituted with residues present in the snake alpha subunit, with an alanine, or with a functionally dissimilar residue. The competitive antagonist alpha-bungarotoxin bound to the fusion protein with high apparent affinity (IC50 = 3.2 x 10(-8) M), and binding was competed by agonists and antagonists. Mutation of His-186, Tyr-189, Tyr-190, Cys-192, Cys-193, Pro-194, and Asp-195 greatly reduced or abolished alpha-bungarotoxin binding, while mutation of Tyr-198 reduced binding, indicating these residues play an important role in binding either through functional interaction with neurotoxin residues or by stabilizing the conformation of the binding site. Molecular modeling of acetylcholine receptor residues 184-200 and knowledge of both neurotoxin and receptor residues essential for binding allow analysis of possible structure-function relationships of the interaction of alpha-bungarotoxin with this region of the receptor.
ESTHER : Chaturvedi_1993_Biochemistry_32_9570
PubMedSearch : Chaturvedi_1993_Biochemistry_32_9570
PubMedID: 8373764

Title : Sodium dodecyl sulfate- and carbamylcholine-induced changes in circular dichroism spectra of acetylcholine receptor synthetic peptides - Donnelly-Roberts_1993_Brain.Res.Mol.Brain.Res_19_55
Author(s) : Donnelly-Roberts D , Lentz TL
Ref : Brain Research Mol Brain Res , 19 :55 , 1993
Abstract : The effect of sodium dodecyl sulfate (SDS) on the conformation of acetylcholine receptor alpha-subunit synthetic peptides was investigated by circular dichroism. In the presence of SDS (0.01-0.02%), the affinity of a 173-204 32 residue peptide and a 172-227 56 residue peptide for the competitive antagonist alpha-bungarotoxin increases about 10-fold to the nanomolar range. Circular dichroism spectroscopy of these peptides revealed significant changes in the secondary structure of the peptides in the presence of SDS at concentrations below the critical micelle concentration. It is concluded that SDS induces a conformation of the peptides that is conductive to high affinity binding. Carbamylcholine, an acetylcholine analog, produced small but significant changes in the spectrum of the 173-204 peptide. This change could be the result of agonist-induced conformational changes in this region of the acetylcholine receptor alpha-subunit or to changes in the asymmetric environments of aromatic chromophores in the binding site. These studies demonstrate that synthetic peptides alone are capable of retaining significant functional activity and contain significant secondary structure.
ESTHER : Donnelly-Roberts_1993_Brain.Res.Mol.Brain.Res_19_55
PubMedSearch : Donnelly-Roberts_1993_Brain.Res.Mol.Brain.Res_19_55
PubMedID: 8361345

Title : Substitution of Torpedo acetylcholine receptor alpha 1-subunit residues with snake alpha 1- and rat nerve alpha 3-subunit residues in recombinant fusion proteins: effect on alpha-bungarotoxin binding - Chaturvedi_1992_Biochemistry_31_1370
Author(s) : Chaturvedi V , Donnelly-Roberts D , Lentz TL
Ref : Biochemistry , 31 :1370 , 1992
Abstract : A fusion protein consisting of the TrpE protein and residues 166-211 of the Torpedo acetylcholine receptor alpha 1 subunit was produced in Escherichia coli using a pATH10 expression vector. Residues in the Torpedo sequence were changed by means of oligonucleotide-directed mutagenesis to residues present in snake alpha 1 subunit and rat nerve alpha 3 subunit which do not bind alpha-bungarotoxin. The fusion protein of the Torpedo sequence bound 125I-alpha-bungarotoxin with high affinity (IC50 = 2.5 x 10(-8) M from competition with unlabeled toxin, KD = 2.3 x 10(-8) M from equilibrium saturation binding data). Mutation of three Torpedo residues to snake residues, W184F, K185W, and W187S, had no effect on binding. Conversion of two additional Torpedo residues to snake, T191S and P194L, reduced alpha-bungarotoxin binding to undetectable levels. The P194L mutation alone abolished toxin binding. Mutation of three Torpedo alpha 1 residues to neuronal alpha 3-subunit residues, W187E, Y189K, and T191N, also abolished detectable alpha-bungarotoxin binding. Conversion of Try-189 to Asn which is present in the snake sequence (Y189N) abolished toxin binding. It is concluded that in the sequence of the alpha subunit of Torpedo encompassing Cys-192 and Cys-193, Try-189 and Pro-194 are important determinants of alpha-bungarotoxin binding. Tyr-189 may interact directly with cationic groups or participate in aromatic-aromatic interactions while Pro-194 may be necessary to maintain a conformation conductive to neurotoxin binding.
ESTHER : Chaturvedi_1992_Biochemistry_31_1370
PubMedSearch : Chaturvedi_1992_Biochemistry_31_1370
PubMedID: 1736994

Title : Binding sites for alpha-bungarotoxin and the noncompetitive inhibitor phencyclidine on a synthetic peptide comprising residues 172-227 of the alpha-subunit of the nicotinic acetylcholine receptor - Donnelly-Roberts_1991_Biochemistry_30_7484
Author(s) : Donnelly-Roberts D , Lentz TL
Ref : Biochemistry , 30 :7484 , 1991
Abstract : The binding of the competitive antagonist alpha-bungarotoxin (alpha-Btx) and the noncompetitive inhibitor phencyclidine (PCP) to a synthetic peptide comprising residues 172-227 of the alpha-subunit of the Torpedo acetylcholine receptor has been characterized. 125I-alpha-Btx bound to the 172-227 peptide in a solid-phase assay and was competed by alpha-Btx (IC50 = 5.0 x 10(-8) M), d-tubocurarine (IC50 = 5.9 X 10(-5)M), and NaCl (IC50 = 7.9 x 10(-2)M). In the presence of 0.02% sodium dodecyl sulfate, 125I-alpha-Btx bound to the 56-residue peptide with a KD of 3.5 nM, as determined by equilibrium saturation binding studies. Because alpha-Btx binds to a peptide comprising residues 173-204 with the same affinity and does not bind to a peptide comprising residues 205-227, the competitive antagonist and hence agonist binding site lies between residues 173 and 204. After photoaffinity labeling, [3H]PCP was bound to the 172-227 peptide. [3H]PCP binding was inhibited by chlorpromazine (IC50 = 6.3 x 10(-5)M), tetracaine (IC50 = 4.2 x 10(-6)M), and dibucaine (IC50 = 2.7 x 10(-4)M). Equilibrium saturation binding studies in the presence of 0.02% sodium dodecyl sulfate showed that [3H]PCP bound at two sites, a major site of high affinity with an apparent KD of 0.4 microM and a minor low-affinity site with an apparent KD of 4.6 microM. High -affinity binding occurred at a single site on peptide 205-227 (KD = 0.27 microM) and was competed by chlorpromazine but not by alpha-Btx.(ABSTRACT TRUNCATED AT 250 WORDS)
ESTHER : Donnelly-Roberts_1991_Biochemistry_30_7484
PubMedSearch : Donnelly-Roberts_1991_Biochemistry_30_7484
PubMedID: 1854749

Title : Structural and conformational similarity between synthetic peptides of curaremimetic neurotoxins and rabies virus glycoprotein - Donnelly-Roberts_1991_Brain.Res.Mol.Brain.Res_11_107
Author(s) : Donnelly-Roberts D , Lentz TL
Ref : Brain Research Mol Brain Res , 11 :107 , 1991
Abstract : Antibodies were raised in rabbits against synthetic peptides corresponding to loop 2, the 'toxic' loop reacting with the acetylcholine-binding site on the nicotinic acetylcholine receptor, of curaremimetic neurotoxins and the structurally similar segment of the rabies virus glycoprotein. Some of the antibodies cross-reacted with the corresponding peptides confirming the structural similarity between the neurotoxin and glycoprotein peptides. A polyclonal antibody raised against a 29 residue glycoprotein peptide (175-203) in the presence of 0.1% sodium dodecyl sulfate reacted with native alpha-bungarotoxin and rabies virus. Circular dichroism spectroscopy of the 29 residue glycoprotein peptide and a 20 residue king cobra loop 2 peptide (25-44) revealed these peptides to be conformationally similar and composed predominantly of beta sheet structure. These results show the rabies glycoprotein segment is structurally and conformationally similar to neurotoxin loop 2. This similarity may confer on the glycoprotein the capability of interacting with the neurotoxin-binding site on the acetylcholine receptor.
ESTHER : Donnelly-Roberts_1991_Brain.Res.Mol.Brain.Res_11_107
PubMedSearch : Donnelly-Roberts_1991_Brain.Res.Mol.Brain.Res_11_107
PubMedID: 1661807

Title : Antibodies against an alpha-bungarotoxin-binding peptide of the alpha-subunit of the acetylcholine receptor - Donnelly-Roberts_1989_Biochem.Biophys.Res.Commun_160_289
Author(s) : Donnelly-Roberts D , Lentz TL
Ref : Biochemical & Biophysical Research Communications , 160 :289 , 1989
Abstract : Polyclonal and monoclonal antibodies were raised against a peptide comprising residues 173-204 of the alpha-subunit of the acetylcholine receptor. The polyclonal and pooled monoclonal antibodies inhibited up to 50% of 125I-alpha-bungarotoxin binding to peptide 173-204. Some of the antibodies recognized native receptor but did not significantly affect alpha-bungarotoxin binding. Epitope mapping revealed that the antibodies are directed against residues 183-194 indicating this region is a major determinant of toxin binding. This region is most likely conformationally constrained in the native receptor.
ESTHER : Donnelly-Roberts_1989_Biochem.Biophys.Res.Commun_160_289
PubMedSearch : Donnelly-Roberts_1989_Biochem.Biophys.Res.Commun_160_289
PubMedID: 2469418

Title : Synthetic peptides of neurotoxins and rabies virus glycoprotein behave as antagonists in a functional assay for the acetylcholine receptor - Donnelly-Roberts_1989_Pept.Res_2_221
Author(s) : Donnelly-Roberts D , Lentz TL
Ref : Pept Res , 2 :221 , 1989
Abstract : Peptides of portions of loop 2 (the "toxic" loop) of snake venom curare-mimetic neurotoxins (alpha-bungarotoxin and king cobra toxin b) and of a structurally similar region of the rabies virus glycoprotein were synthesized. The effect of the peptides on carbachol-induced 22Na+ flux into BC3H-1 cells, which contain nicotinic acetylcholine receptors on their surfaces, was measured. Both the neurotoxin and glycoprotein peptides inhibited ion transport with IC50 values of 10(-4) M to 7 x 10(-7) M. The most effective peptides correspond to neurotoxin loop 2 and inhibited 22Na+ flux in the micromolar range comparable to the competitive antagonist d-tubocurarine. These findings show that neurotoxin loop 2 and the corresponding rabies virus glycoprotein segment interact with the agonist binding site of teh acetylcholine receptor and that short synthetic peptides representing portions of larger molecules by themselves can exert a biological effect on a large macromolecular complex like the acetylcholine receptor.
ESTHER : Donnelly-Roberts_1989_Pept.Res_2_221
PubMedSearch : Donnelly-Roberts_1989_Pept.Res_2_221
PubMedID: 2520759

Title : Synthetic peptides in the study of the interaction of rabies virus and the acetylcholine receptor - Lentz_1988_Adv.Biochem.Psychopharmacol_44_57
Author(s) : Lentz TL , Hawrot E , Donnelly-Roberts D , Wilson PT
Ref : Adv Biochem Psychopharmacol , 44 :57 , 1988
Abstract : The neurotropism of some viruses may be explained in part by the attachment of these viruses to host cell receptors that are present on or even largely restricted to neurons. Rabies virus is an RNA virus that, after a period of replication in muscle, gains access to the central nervous system, where it selectively infects certain neuronal populations. The nicotinic acetylcholine receptor occurs in high density at the neuromuscular junction and is present in the central nervous system. Although several different cell surface constituents may act as attachment determinants for rabies, direct binding of radioactively labeled virus to affinity-purified acetylcholine receptor has been demonstrated. Binding of virus to the receptor was saturable and inhibited by up to 50% by alpha-bungarotoxin, a snake venom neurotoxin that binds at or near the acetylcholine binding site on the receptor. The molecular basis for the virus-receptor interaction may lie in an amino acid sequence similarity between the snake venom neurotoxins and a segment of the rabies virus glycoprotein. Two peptides (10 and 13 residues) of the rabies virus glycoprotein and homologous bungarotoxin peptides were synthesized and tested for ability to compete with labeled alpha-bungarotoxin for binding to the acetylcholine receptor. The peptides were found to compete with toxin binding with affinities comparable to those of the cholinergic ligands d-tubocurarine and nicotine. These findings indicate that a segment of the rabies virus glycoprotein interacts with the acetylcholine receptor at or near the acetylcholine binding site of the receptor. The similarity between the virus glycoprotein and the neurotoxin was further evidenced by the cross reaction of antibody raised against the virus 10-mer with the bungarotoxin 10-mer. Binding of rabies virus to the acetylcholine receptor or to other neuronal bungarotoxin-binding proteins may be related to the neurotropism of this virus. In addition, knowledge of both the region of the virus involved in binding and the binding domain on the receptor may be helpful in developing new strategies for treatment, especially for viruses that infect the central nervous system or evade the immune response through genetic drift. These strategies include development of antiviral agents that cross the blood-brain barrier and inhibit viral binding and the utilization as immunogens the regions of viruses, such as their binding domains, that are highly conserved among different strains.
ESTHER : Lentz_1988_Adv.Biochem.Psychopharmacol_44_57
PubMedSearch : Lentz_1988_Adv.Biochem.Psychopharmacol_44_57
PubMedID: 3041753