Role of estrogens in hypothalamic inflammation and metabolic regulation.

项目摘要 肥胖是一个严重的公共卫生威胁，因为它大大增加了高度病态的慢性疾病的风险。 包括2型糖尿病、高血压、心血管疾病和许多癌症的疾病。目前，在 60%的美国人超重或肥胖，缺乏有效的治疗方法， 减少肥胖使我们有必要集中精力解开肥胖及其相关机制 代谢紊乱 这项提案的重点是性类固醇保护免受肥胖的大脑机制及其对肥胖的影响。 相关的代谢性疾病。绝经前女性的代谢紊乱率低于绝经后男性。 但绝经后随着体重增加、内脏脂肪堆积、 肥胖和相关合并症的增加。虽然雌激素替代疗法可以逆转许多 这些绝经期的变化，增加癌症和中风的风险与这种治疗排除其 用于一级预防，创造了了解雌激素保护机制的需求 肥胖及其相关的代谢风险。 越来越多的证据表明，肥胖与下丘脑神经元损伤，炎症， 以及反应性神经胶质增生，其特征在于局部小胶质细胞（大脑的巨噬细胞）的活化。啮齿动物 研究表明，减少下丘脑炎症和小胶质细胞活化可限制体重增加 以及饮食引起的肥胖症的代谢并发症。同样，雌激素减少食物摄入， 能量消耗，并能有效抑制脑部炎症。此外，雌性老鼠的抵抗力更强 饮食相关的小胶质细胞激活和体重增加，这表明雌激素和 小胶质细胞信号事实上，我们的初步观察表明，雌激素缺乏增加的迹象， 饮食引起的下丘脑炎症和神经胶质增生这些发现支持了《特定目标》中提出的研究。 1使用动物模型与消融小胶质细胞炎症，以确定是否下丘脑胶质细胞增生， 西式饮食和雌激素缺乏所需的协同作用使肥胖症及其 相关的代谢并发症。此外，我们还开发了具有小胶质细胞特异性的小鼠模型， 雌激素受体α（ERα）或雌激素受体β（ERβ）缺失，以确定是否需要 的小胶质细胞雌激素信号，以防止饮食诱导的肥胖（目的2）。拟议的研究将继续进行 我们对雌激素缺乏如何导致代谢风险的理解，并测试了一种新的雌激素模型- 介导的代谢调节通过行动的小胶质细胞。更广泛地说，这一提议将提供新的中央 机制来解释在低雌激素水平的女性中观察到的更高的代谢风险， 临床前治疗试验的小胶质细胞靶点，以降低这种风险。

Project Summary Obesity is a grave public health threat since it greatly increases the risk of highly morbid chronic diseases including type 2 diabetes, hypertension, cardiovascular disease, and many cancers. Currently, over 60 percent of Americans are overweight or obese, and the lack of effective therapies available for weight reduction make it imperative to focus on unraveling the mechanisms underlying obesity and its associated metabolic disorders. This proposal focuses on brain mechanisms by which sex steroids protect from obesity and its associated metabolic diseases. Premenopausal women have a lower rate of metabolic disorders than men of the same age, but this trend reverses after menopause with increase of weight gain, accumulation of visceral adiposity and increase in associated comorbidities. While estrogen replacement therapy can reverse many of these menopausal changes, the increased cancer and stroke risks associated with this therapy preclude its use for primary prevention, creating a demand for understanding the mechanisms by which estrogen protects from obesity and its associated metabolic risks. Growing evidence suggests that obesity is associated with hypothalamic neuronal injury, inflammation, and reactive gliosis, characterized by activation of local microglia (the macrophage of the brain). Rodent studies have demonstrated that reducing hypothalamic inflammation and microglial activation limits weight gain and the metabolic complications of diet-induced obesity. Similarly, estrogen reduces food intake, increases energy expenditure, and can potently suppress brain inflammation. In addition, female mice are more resistant to diet-associated microglial activation and weight gain, suggesting a potential link between estrogen and microglial signaling. Indeed, our preliminary observations demonstrate that estrogen deficiency increases signs of diet-induced hypothalamic inflammation and gliosis. These findings support studies proposed in Specific Aim 1 to use animal models with ablation of microglial inflammation to determine whether hypothalamic gliosis is required for Western-type diet and estrogen deficiency to synergistically predispose to obesity and its associated metabolic complications. Additionally, we have developed mouse models with microglia-specific deletion of either estrogen receptor alpha (ERα) or estrogen receptor beta (ERβ) to determine the requirement of microglial estrogen signaling to protect from diet-induced obesity (Aim 2). The proposed studies will advance our understanding of how estrogen deficiency confers metabolic risk and test a novel model of estrogen- mediated metabolic regulation through action in microglia. More broadly, this proposal will provide new central mechanisms to explain the higher metabolic risk observed in women with low estrogen levels, and new microglial targets for preclinical therapeutic trials to reduce this risk.