ESTROGEN AND CEREBRAL VASODILATION

雌激素和脑血管舒张

• 批准号: 2029890
• 负责人: DALE Alan PELLIGRINO
• 金额: $ 23.86万
• 依托单位: UNIVERSITY OF ILLINOIS AT CHICAGO
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-12-01 至 2000-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2029890
• 关键词: cerebral ischemia /hypoxia; cerebrovascular system; estrogens; female; histopathology; hormone regulation /control mechanism; laboratory rat; neuropathology; neuroprotectants; nitric oxide; nitric oxide synthase; oxidative stress; vasodilation

The mechanisms involved in estrogen-related brain protection are unclear, but based on findings in the periphery, improved vasodilating capacity through upregulation of a constitutive nitric oxide synthase (cNOS) is an attractive possibility. The proposed studies are designed to examine the effects of estrogens on cerebral vasodilating function and the role of NO in this regard. Results will be compared in 17 beta- estradiol (E2)-treated and untreated ovariectomized (OVX) rats and normal females. There are 3 principal aims. For aim 1, the studies will evaluate: a) No-dependent cerebral vasodilatory responses, in the 3 groups, via monitoring changes in pial arteriolar diameters during suffusions of a NO donor (SNAP), a NO-independent vasodilator (adenosine), and endothelial cNOS (eNOS) and neuronal cNOS (nNOS)- dependent vasodilators (acetylcholine and NMDA, respectively); b) NOS activity and eNOS/nNOS mRNA and protein expression in the 3 groups; c) dose (0.01 to 5 mg kg -1 day) and time (1-14 days) -related changes in eNOS/nNOS activity and expression and vasodilating function associated with E2 treatment and withdrawal in OVX rats; d) variations in cNOS isoform expression and NO-dependent vasodilation that may occur during the estrous cycle in normal females; and e) using estrogen receptor (ER) antagonists (1C1 182780, tamoxifen--co-administered with E2), whether ERs are involved in E2-related changes in cNOS expression/function. In addressing aim 2, experiments will examine acute dose-dependent effects of E2 suffusions on pial arteriolar relaxation in the presence and absence of NOS inhibition and in the presence and absence of ER antagonists. NOS isoform specificity will be tested using the nNOS inhibitor, ARL 17477AR and the non-specific inhibitor, nitro-L-arginine (L-NA) eNOS contributions are estimated by difference. For aim 3, a transient forebrain ischemia (TFI) model will be used (carotid occlusion + hypotension). Using laser-Doppler flowmetry (LDF), intra-ischemic cerebral cortical blood flow (CCBF) changes will be monitored and compared in the 3 groups, followed by postischemic assessments of neuropathology. As for aim 1 studies, the data will be evaluated with respect to estrous cycle stage (normals), time and dose-related effects of E2 treatment and withdrawal (OVX), and ER antagonist effects (chronic co-administration with E2). The relative roles of nNOS vs eNOS in contributing to intra-ischemic vasodilation (using iv ARL 17477AR and L- NA) will also be examined. In several groups (i.e., those showing the greatest CCBF fall during ischemia [e.g., untreated OVX]), the intra- ischemic CCBF reductions (instead of arterial pressure) will be matched to that observed in the OVX group showing the greatest E2 treatment benefit. These results should provide important information about the cerebrovascular influences of estrogen.

雌激素相关的脑保护机制包括 不清楚，但基于外周的发现，血管舒张改善 通过上调组成型一氧化氮合酶的能力 （cNOS）是一个有吸引力的可能性。 拟议的研究旨在 研究雌激素对脑血管舒张功能的影响 以及NO在这方面的作用。 结果将在17个beta中进行比较- 雌二醇（E2）处理和未处理的卵巢切除（OVX）大鼠， 正常的女性有三个主要目标。 对于目标1，研究将 评价：a）非依赖性脑血管舒张反应，在3 组，通过监测软脑膜小动脉直径的变化， NO供体（SNAP），一种NO非依赖性血管扩张剂 （腺苷），内皮cNOS（eNOS）和神经元cNOS（nNOS）- 依赖性血管扩张剂（分别为乙酰胆碱和NMDA）; B）NOS c）各组eNOS活性及eNOS/nNOS mRNA和蛋白表达; 剂量（0.01至5 mg kg-1天）和时间（1-14天）相关变化 eNOS/nNOS活性和表达与血管舒张功能相关 在OVX大鼠中用E2处理和戒断; d）cNOS的变化 亚型表达和NO依赖性血管舒张，可能发生在 正常雌性的动情周期;和e）使用雌激素受体（ER） 拮抗剂（1C 1 182780，他莫昔芬-与E2共同给药），无论 ER参与cNOS表达/功能的E2相关变化。 在 针对目标2，实验将检查急性剂量依赖效应 E2灌注对软脑膜小动脉舒张的影响， 不存在NOS抑制以及存在和不存在ER 对手。 将使用nNOS检测NOS亚型特异性 抑制剂ARL 17477 AR和非特异性抑制剂硝基-L-精氨酸 （L-NA）eNOS贡献通过差异估计。 对于目标3，a 将使用短暂前脑缺血（TFI）模型（颈动脉闭塞 + 低血压）。 使用激光多普勒血流仪（LDF）， 将监测大脑皮质血流量（CCBF）的变化， 比较3组，然后进行缺血后评估， 神经病理学 对于目标1研究，将使用以下方法评价数据： 关于发情周期阶段（正常）、时间和剂量相关效应 E2治疗和停药（OVX），以及ER拮抗剂效应（慢性） 与E2共同施用）。 nNOS与eNOS在肿瘤发生中的相对作用 促进缺血内血管舒张（使用iv ARL 17477 AR和L- NA）也将进行检查。 在几个组中（即，那些显示 局部缺血期间最大CCBF下降[例如，未治疗的OVX]）， 将匹配缺血性CCBF降低（而不是动脉压） OVX组中观察到的E2治疗量最大 效益 这些结果应该提供关于 雌激素对脑血管的影响