Estrogen and cerebrovascular physiology and pathophysiology

Numerous studies have uncovered a wide variety of estrogen effects with app arent cardiovascular benefits, the most recognized ones being vasodilation, anti-atherogenesis, diminished post-ischemic inflammation and anti-oxidant effects. This article provides an overview of the influence of estrogen on the cerebral vasculature, under physiologic and pathophysiologic condition s, and covers both acute and chronic effects. The discussion is primarily f ocused on the vasodilatory and anti-inflammatory actions of estrogen, since those particular estrogen influences have received the greatest attention in studies published to date. With respect to vasodilation, although some c onsideration is given to the role of other vasodilating mechanisms and fact ors, the emphasis is mostly placed on the endothelial isoform of nitric oxi de synthase, eNOS, which has emerged as a clear target of estrogen. Some co nsideration is given to recent findings that suggest that estrogen can stim ulate eNOS activity by decreasing the expression of the eNOS inhibitor cave olin-1. With regard to the ability of estrogen to counteract inflammation, potential mechanisms by which estrogen limits the post-ischemic leukocyte a dhesion, and the expression of the inducible NOS, are discussed.