Endothelial Aromatase in Sex-Specific Cerebrovascular Dysfunction After Ischemia

描述（由申请人提供）：与年龄匹配的男性相比，女性的中风风险和死亡率较低。虽然这种保护似乎是通过卵巢雌激素介导的，但卵巢激素并不能解释女性中所见的所有保护作用，因为女性保护即使在绝经后卵巢雌激素丢失时也会持续存在。在绝经后妇女中，雌激素的主要来源变为通过芳香酶的雌二醇的局部（性腺外）合成。芳香化酶在许多细胞类型中表达，包括血管内皮细胞（EC）。在雌性小鼠中，芳香化酶基因缺失和药物抑制均导致脑缺血后更差的结果，表明芳香化酶起保护作用。因此，要测试的假设是，由于内皮特异性芳香化酶的表达和活性较高，与男性相比，女性在脑缺血后免受脑血管功能障碍的影响。为了确定是否有 小鼠脑缺血后脑血管内皮功能障碍的性别差异，将使用体内颅窗准备和光学微血管造影成像，在短暂性大脑中动脉闭塞（tMCAO，1h）或假手术之前和之后比较雄性和雌性小鼠对内皮依赖性血管舒张剂乙酰胆碱（ACh）的反应。为了确定tMCAO后内皮依赖性舒张的性别差异是否由芳香酶介导，将在两种性别的野生型和芳香酶敲除小鼠之间比较tMCAO或假手术前后的ACh反应。最后，为了确定EC特异性芳香酶表达和脑血管芳香酶活性是否存在性别差异，将在基线或tMCAO或假手术后从雄性和雌性小鼠分离的脑血管中比较EC特异性芳香酶mRNA和蛋白质表达以及脑血管芳香酶活性。了解EC对芳香化酶的特异性调节可能会导致治疗策略，旨在增强内皮细胞内特异性的局部雌二醇产生，从而避免与全局雌激素给药相关的负面副作用，但保持雌激素对血管的保护作用。

DESCRIPTION (provided by applicant): Women have lower stroke risk and mortality compared to age-matched men. While some of this protection appears to be mediated via ovarian estrogen, ovarian hormones do not account for all of the protective effects seen in females since female protection persists even after menopause when ovarian estrogen is lost. In post- menopausal women, the major source of estrogen becomes local (extra-gonadal) synthesis of estradiol by the enzyme aromatase. Aromatase is expressed in numerous cell types, including vascular endothelial cells (EC). In female mice, both aromatase gene deletion and pharmacological inhibition lead to worse outcome following cerebral ischemia, suggesting that aromatase plays a protective role. Therefore, the hypothesis to be tested is that females are protected from cerebrovascular dysfunction following cerebral ischemia compared to males due to higher expression and activity of endothelial-specific aromatase. In order to determine if there are sex differences in cerebrovascular endothelial dysfunction following cerebral ischemia in mice, responses to the endothelium-dependent vasodilator acetylcholine (ACh) will be compared in male and female mice before and after transient middle cerebral artery occlusion (tMCAO, 1h) or sham surgery using an in vivo cranial window preparation and optical microangiography imaging. To determine if sex differences in endothelium-dependent dilation after tMCAO are mediated by aromatase, ACh responses before and after tMCAO or sham surgery will be compared between wild-type and aromatase knockout mice of both sexes. Finally, to determine if there are sex differences in EC-specific aromatase expression and cerebrovascular aromatase activity, EC-specific aromatase mRNA and protein expression and cerebrovascular aromatase activity will be compared in cerebral vessels isolated from male and female mice at baseline or after tMCAO or sham surgery. Understanding EC specific regulation of aromatase may lead to therapeutic strategies aimed at enhancing local estradiol production specifically within endothelial cells, thus avoiding the negative side effects associated with global estrogen administration, but maintaining the protective effects of estrogen on the vasculature.