Inducible nitric oxide synthase and estradiol exhibit complementary neuroprotective roles after ischemic brain injury.
Estradiol-17beta exerts profound neuroprotective actions following cerebral ischemia through multiple molecular mechanisms. To examine the putative anti-inflammatory mechanisms employed by estradiol during stroke, we explored the interactions between estradiol and inducible nitric oxide synthase (iNOS) in both wildtype and iNOS knockout (iNOSKO) female mice following permanent middle cerebral artery occlusion (MCAO). Female mice were ovariectomized and treated with estradiol. One week later, they were subjected to MCAO, and then killed 24 h later. Analysis of total, cortical and striatal infarct volumes confirmed that estradiol is neuroprotective in wildtype mice. Infarct volumes were also significantly smaller in female iNOSKO female mice, but estradiol did not further decrease injury. We found that one mechanism by which estradiol may act is by decreasing nitric oxide synthase 2 gene expression in the cortex and in the striatum of wildtype mice. These results show that the pro-inflammatory actions of iNOS exacerbate stroke-induced injury within the cortex and striatum, and that iNOS deletion is neuroprotective in ovariectomized and estrogen-replaced female mice.
Brown
Candice M
CM
Department of Physiology and Biophysics, University of Washington, Seattle, WA 98195, USA. canbrown@u.washington.edu
Dela Cruz
Christopher D
CD
Yang
Enhua
E
Wise
Phyllis M
PM
D000704:Analysis of Variance; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000473:pathology; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000187:drug effects; D004958:Estradiol / Q000008:administration & dosage*; D004967:Estrogens / Q000008:administration & dosage*; D005260:Female; D020244:Infarction, Middle Cerebral Artery / Q000235:genetics* / Q000473:pathology / Q000517:prevention & control*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D052247:Nitric Oxide Synthase Type II / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D010052:Ovariectomy / Q000379:methods; D013778:Tetrazolium Salts
D004967:Estrogens; D013778:Tetrazolium Salts; D004958:Estradiol; C009591:triphenyltetrazolium; D052247:Nitric Oxide Synthase Type II; C496317:Nos2 protein, mouse