Impact of Endocrine Aging on Brain and Immune Responses

这项应用的目的是确定生殖衰老和雌激素替代改变炎症反应从而改变神经环境的机制。在一系列研究中，我们已经证实，年轻成年动物的雌激素替代增加了前脑的营养支持，并减轻了神经损伤后的炎症。然而，在生殖衰老时补充雌激素，在生理上类似于更年期，并没有增加营养因子，相反，增加了神经损伤后的炎症介质。总而言之，这些数据表明，雌激素替代的时机与生殖衰老有关，这可能是决定是否 雌激素有良性或有害的结果。我们的中心假设是，与年龄相关的内源性激素下降触发了特定免疫细胞中雌激素受体系统的代偿性变化，从而增强了中枢和外周的炎症反应。这一假设将在三个特定的目标上进行验证，使用跨越生殖光谱的动物和人类组织模型，即正常周期(绝经前)。周期不规律(围绝经期)和生殖衰老(绝经后)。在具体目标1中，我们将检验这样一种假设，即与正常循环或不规则循环相比，血脑屏障的允许改变将在生殖衰老动物中引起更迅速和更强烈的神经炎症。动物将被系统地注射这种细菌病原体 将测量外周器官和大脑中的脂多糖(LPS)和炎症介质。此外，我们还将检查血脑屏障内皮细胞的生殖年龄相关变化。在具体目标2中，我们将确定外周血单个核细胞(PBMC)的炎症反应是否受到临床相关变量的影响，即激素的给药途径(口服与经皮)和饮食(常规与高胆固醇)。从体外脂多糖挑战测试中得出的响应商将在大鼠和人类的血液样本中进行测量，以确定显著的生活方式变量是否会增加与生殖衰老相关的风险。最后，在 具体目的3我们将检验这样一种假设，即卵巢衰退引起的雌激素受体系统的代偿性改变是雌激素在生殖衰老中有害作用的主要机制。雌激素受体(ER)-α的模式和水平的变化将通过免疫组织化学和Western blotts来评估，而功能的变化将通过信号阵列来评估。将研究每个生殖阶段的人和啮齿动物的PBMC和啮齿动物脑内皮细胞。总而言之，这些研究将检验这一假设，即为了使雌激素替代有效，必须在对卵巢功能下降的代偿反应之前开始治疗。

The goal of this application is to determine the mechanisms by which reproductive aging and estrogen replacement alter the inflammatory response and consequently the neuronal environment. In a series of studies, we have established that estrogen replacement to young adult animals increases trophic support in the forebrain and attenuates inflammation following neural injury. However estrogen replacement at reproductive senescence, which is physiologically akin to menopause, fails to increase trophic factors and paradoxically, increases inflammatory mediators following neural injury. Collectively these data suggest that the timing of estrogen replacement in relation to reproductive aging may critically determine whether estrogen has a benign or deleterious outcome. Our central hypothesis is that the age-related decline in endogenous hormones triggers compensatory changes in estrogen receptor systems in specific immune cells, thus increasing the central and peripheral inflammatory response. This hypothesis will be tested in three Specific Aims, using animal and human tissue models that span the reproductive spectrum, namely, normally cycling (pre-menopause). irregularly cycling (perimenopause) and reproductive senescent (postmenopause). In Specific Aim 1. we will test the hypothesis that permissive changes in the blood brain barrier will cause a more rapid and robust neural inflammation in reproductive senescent animals as compared to normally cycling or irregularly cycling animals. Animals will be injected systemically with the bacterial pathogen lipopolysaccharide (LPS) and inflammatory mediators will be measured in peripheral organs and the brain. Additionally, we will examine endothelial cells of the blood-brain barrier for reproductive age-related changes in this barrier. In Specific Aim 2. we will determine if the inflammatory response of peripheral blood mononuclear cells (PBMC) is affected by clinically-relevant variables namely, the route of hormone administration (oral versus transdermal) and diet (regular versus high cholesterol). The Response Quotient, derived from an ex vivo LPS challenge assay, will be measured in rat and human blood samples to determine if salient lifestyle variables increase the risks associated with reproductive aging. Finally, in Specific Aim 3 we will test the hypothesis that compensatory alterations of the estrogen receptor system, resulting from ovarian decline, is a principal mechanism underlying estrogen's deleterious effects in reproductive senescence. Changes in the pattern and levels of estrogen receptor (ER)-alpha will be evaluated by immunohistochemistry and Western blots, while functional changes will be evaluated using signaling arrays. Human and rodent PBMC's and rodent cerebral endothelial cells from each reproductive stage will be studied. Collectively, these studies will test the hypothesis that in order for estrogen replacement to be beneficial, therapy must be initiated before compensatory responses to ovarian decline.