P450 eicosanoids are important regulators of the cerebral microcirculation, but their role in cerebral small vessel disease is unclear. We tested the hypothesis that vascular cognitive impairment (VCI) is linked to reduced cerebral microvascular eicosanoid signaling. We analyzed human brain tissue from individuals formerly enrolled in the Oregon Brain Aging Study, who had a history of cognitive impairment histopathological evidence of microvascular disease. VCI subjects had significantly higher lesion burden both on premortem MRI and postmortem histopathology compared to age- and sex-matched controls. Mass spectrometry-based eicosanoid analysis revealed that 14,15-dihydroxyeicosatrienoic acid (DHET) was elevated in cortical brain tissue from VCI subjects. Immunoreactivity of soluble epoxide hydrolase (sEH), the enzyme responsible for 14,15-DHET formation, was localized to cerebral microvascular endothelium, and was enhanced in microvessels of affected tissue. Finally, we evaluated the genotype frequency of two functional single nucleotide polymorphisms of sEH gene EPHX2 in VCI and control groups. Our findings support a role for sEH and a potential benefit from sEH inhibitors in age-related VCI.
Title: Soluble epoxide hydrolase: sex differences and role in endothelial cell survival Gupta NC, Davis CM, Nelson JW, Young JM, Alkayed NJ Ref: Arterioscler Thromb Vasc Biol, 32:1936, 2012 : PubMed
OBJECTIVE: Sex differences in cerebral ischemic injury are, in part, attributable to the differences in cerebrovascular perfusion. We determined whether the brain microvascular endothelial cells (ECs) isolated from the female brain are more resistant to ischemic injury compared with male ECs, and whether the difference is attributable to lower expression of soluble epoxide hydrolase and higher levels of vasoprotective epoxyeicosatrienoic acids (EETs). We also determined whether protection by EETs is linked to the inhibition of rho-kinase (ROCK). METHODS AND RESULTS: EC ischemic damage was measured after oxygen-glucose deprivation (OGD) using propidium iodide (PI) and cleaved caspase-3 labeling. Expression of soluble epoxide hydrolase was determined by quantitative polymerase chain reaction and immunocytochemistry, EETs levels by liquid chromatography-tandem mass spectrometry, and ROCK activity by ELISA. EC damage was higher in males compared with females, which correlated with higher soluble epoxide hydrolase mRNA, stronger immunoreactivity, and lower EETs compared with female ECs. Inhibition of soluble epoxide hydrolase abolished the sex difference in EC damage. ROCK activity was higher in male versus female ECs after OGD, and sex differences in EC damage and ROCK activity were abolished by 14,15-EET and ROCK inhibition. CONCLUSIONS: Sex differences in ischemic brain injury are, in part, attributable to differences in EET-mediated inhibition of EC ROCK activation after ischemia.
The laboratory rat (Rattus norvegicus) is an indispensable tool in experimental medicine and drug development, having made inestimable contributions to human health. We report here the genome sequence of the Brown Norway (BN) rat strain. The sequence represents a high-quality 'draft' covering over 90% of the genome. The BN rat sequence is the third complete mammalian genome to be deciphered, and three-way comparisons with the human and mouse genomes resolve details of mammalian evolution. This first comprehensive analysis includes genes and proteins and their relation to human disease, repeated sequences, comparative genome-wide studies of mammalian orthologous chromosomal regions and rearrangement breakpoints, reconstruction of ancestral karyotypes and the events leading to existing species, rates of variation, and lineage-specific and lineage-independent evolutionary events such as expansion of gene families, orthology relations and protein evolution.
Title: Determination of the number of muscarinic receptors in chick amnion muscle Cuthbert AW, Young JM Ref: British Journal of Pharmacology, 47:631P, 1973 : PubMed
1. [(3)H]-Propyl benzilylcholine mustard ([(3)H]-PrBCM) an irreversible specific antagonist of muscarinic acetylcholine receptors, has been used to label the muscarinic receptors in the aneuronal muscle of isolated 11 day amniotic membranes of chick embryos.2. This muscle was found to have about 9 fmol/mg dry weight of receptor material. This is only 1-2% of the amount found in intestinal muscle.3. Pharmacological studies with isolated amniotic membranes using PrBCM show that labelling is to functional receptors and that the receptor reserve is small.4. The significance of the difference in receptor reserve in innervated and aneuronal plain muscle is discussed.
