Biological Mechanisms of Vascular Dysfunction with Age and Estrogen Deficiency

描述(由申请人提供)：这项竞争性续签申请(R01 AG027678)将对响应RFA-AG-05-008“围绝经期生物学：对健康和老龄化的影响”的研究进行延伸和扩展。第一个获奖期的研究结果表明：1)内皮功能(内皮依赖性扩张；EDD)随着卵巢功能的下降而变得更加受损，2)氧化应激是EDD受损的潜在机制之一。这一更新应用的全球目标是确定四氢生物蝶呤(BH4；内皮型一氧化氮合酶(ENOS)和一氧化氮[NO]合成的重要辅助因子)和eNOS解偶联作为女性绝经过渡和衰老的氧化应激相关内皮功能障碍的潜在介质的作用。在目标1中，将通过对健康的绝经前、围绝经期和绝经后妇女的横断面比较来评估这一点。内皮功能将在基础条件下和在BH4急剧增加后进行测量。目的2通过在绝经前和围绝经期妇女中使用促性腺激素释放激素拮抗剂[GnRHant]短期(10天)抑制雌激素(E_2)来扩大横断面比较，以确定E_2对EDD的非年龄效应。目标3将研究BH4和抗氧化剂(抗坏血酸；AA)联合应用恢复EDD的情况。主要的假设是，口服BH4后，围绝经期和绝经后妇女，以及短期抑制E2后，绝经前和围绝经期妇女的EDD将增加。第二个假说预测，围绝经期和绝经后妇女的EDD降低(在基线和抑制E2的情况下)将与BH4生物合成的血浆和内皮细胞蛋白标记物以及血管内皮细胞的氧化应激有关。第三种假设是，联合服用BH4和AA将使围绝经期和绝经后妇女的EDD恢复到绝经前妇女的水平。为了验证这些假说，将在1)围绝经期前和早期妇女在短期E2抑制(GnRHant)和补充E2透皮贴剂或安慰剂后进行测量；以及2)绝经后妇女基线。为了确定内皮功能障碍的可能机制，还将在口服BH4单独补充和AA注射期间测量EDD。对EDD降低背后的分子事件的洞察将通过评估内皮细胞参与调节细胞和系统对E2缺乏的适应的蛋白质表达的变化来确定，包括BH4的生物合成和氧化应激。[这项研究的结果应该会扩展我们早期的发现，并进一步阐明在更年期过渡阶段调节内皮功能障碍的机制，以及这些过程是否由雌激素缺乏引发。了解这些机制缺陷将有助于了解干预的关键窗口，并指导未来针对性别的干预和治疗，以维持血管功能和预防未来的心血管疾病。]

DESCRIPTION (provided by applicant): This competing renewal application (R01 AG027678) will extend and expand on research that was responsive to RFA-AG-05-008 "Biology of the Perimenopause: Impact on Health and Aging." Findings from the first award period demonstrate that: 1) endothelial function (endothelium-dependent dilation; EDD) becomes more impaired with declining ovarian function, and 2) oxidative stress is one of the underlying mechanisms involved in impaired EDD. The global aim of this renewal application is to determine the role of tetrahydrobiopterin (BH4; an essential cofactor for endothelial nitric oxide synthase (eNOS) and nitric oxide [NO] synthesis) and eNOS uncoupling as potential mediators of oxidative stress-related endothelial dysfunction with the menopause transition and aging in women. This will be assessed in Aim 1 using cross-sectional comparisons of healthy pre-, peri- and postmenopausal women. Endothelial function will be measured under basal conditions and following an acute increase in BH4. Aim 2 will expand on the cross-sectional comparisons by using short-term (10 days) suppression of estrogen (E2) using gonadotropin releasing hormone antagonist [GnRHant] in pre-and perimenopausal women to determine the age-independent effects of E2 on EDD. Aim 3 will examine the co-administration of BH4 and an anti-oxidant (ascorbic acid; AA) for the restoration of EDD. The primary hypotheses are that the reduced EDD in peri- and postmenopausal women, and in pre- and perimenopausal women following short-term E2 suppression, will increase in response to oral BH4. Secondary hypotheses predict that the reduced EDD in peri- and postmenopausal women (at baseline and with E2 suppression) will be associated with plasma and endothelial cell protein markers of BH4 biosynthesis and oxidative stress in vascular endothelial cells. A tertiary hypothesis is that the co-administration of BH4 an AA will restore EDD in peri-and postmenopausal women to levels of premenopausal women. To test these hypotheses, brachial artery EDD will be measured in: 1) pre-and early perimenopausal women before and after short-term E2 suppression (GnRHant) and add-back of either transdermal E2 or placebo; and 2) postmenopausal women at baseline. To determine possible mechanisms for endothelial dysfunction, EDD will also be measured after oral BH4 supplementation alone and during AA infusion. Insight into the molecular events underlying the decrease in EDD will be determined by assessing the changes in endothelial cell expression of proteins involved in the regulation of cellular and systemic adaptations to E2 deficiency including BH4 biosynthesis and oxidative stress. [The results from this research should expand our earlier findings and elucidate further the mechanisms that mediate endothelial dysfunction across the stages of the menopause transition and whether these processes are triggered by E2 deficiency. Understanding these mechanistic defects will help to inform the critical window of intervention and guide future sex-specific interventions and therapies for the maintenance of vascular function and prevention of future cardiovascular diseases.]