Huang_2014_Psychopharmacology.(Berl)_231_4541

BACKGROUND: Alpha7 and alpha4beta2 nicotinic acetylcholine receptor (nAChR) agonists have been shown to improve cognition in various animal models of cognitive impairment and are of interest as treatments for schizophrenia, Alzheimer's disease, and other cognitive disorders. Increased release of dopamine (DA), acetylcholine (ACh), glutamate (Glu), and gamma-aminobutyric acid (GABA) in cerebral cortex, hippocampus, and nucleus accumbens (NAC) has been suggested to contribute to their beneficial effects on cognition.
RESULTS: Using in vivo microdialysis, we found that EVP-6124 [(R)-7-chloro-N-quinuclidin-3-yl)benzo[b]thiophene-2-carboxamide], a high-affinity alpha7 nAChR partial agonist, at 0.1 mg/kg, s.c., increased DA efflux in the medial prefrontal cortex (mPFC) and NAC. EVP-6124, 0.1 and 0.3 mg/kg, also increased efflux of ACh in the mPFC but not in the NAC. Similarly, EVP-6124, 0.1 mg/kg, but not 0.03 and 0.3 mg/kg, significantly increased mPFC Glu efflux. Thus, EVP-6124 produced an inverted U-shaped curve for DA and Glu release, as previously reported for other alpha7 nAChR agonists. The three doses of EVP-6124 did not produce a significant effect on GABA efflux in either region. Pretreatment with the selective alpha7 nAChR antagonist, methyllycaconitine (MLA, 1.0 mg/kg), significantly blocked cortical DA and Glu efflux induced by EVP-6124 (0.1 mg/kg), suggesting that the effects of EVP-6124 on these neurotransmitters were due to alpha7 nAChR agonism. MLA only partially blocked the effects of EVP-6124 on ACh efflux in the mPFC. CONCLUSION: These results suggest increased cortical DA, ACh, and Glu release, which may contribute to the ability of the alpha7 nAChR agonist, EVP-6124, to treat cognitive impairment and possibly other dimensions of psychopathology.