Physiology of Hypothalamic Neurosteroidal Progesterone

描述（由申请人提供）：神经类固醇，在大脑中从头合成的类固醇，涉及从压力、抑郁、焦虑到认知的功能。一种神经类固醇是黄体酮，一种典型的参与生殖调节的性激素。我们以前已经表明，外周雌二醇（E2）增加下丘脑神经孕酮（neuroP）的合成，启动黄体生成素（LH）激增。LH激增触发排卵和破裂卵泡的黄素化--这是生殖过程中的关键事件。在下丘脑内，星形胶质细胞通过增加neuroP合成来响应E2刺激。初步数据表明，E2信号需要膜相关雌激素受体1（mER 1）和1组代谢型谷氨酸受体（mGluR 1a）之间的相互作用。由此产生的游离细胞质钙的升高足以刺激neuroP的合成。由于控制LH激增的GnRH神经元没有类固醇受体，因此需要其他神经元将类固醇信息传递给它们。Kisspeptin神经元被认为是这些介入神经元：它们投射到GnRH神经元，有效地激发它们，并表达ER 1和孕酮受体（PR）。基于这些结果，我们建议测试的假设，雌激素正反馈需要E2诱导的neuroP合成涉及mER 1和mGluR 1a的相互作用，和kisspeptin神经元的激活。本论文提出了三个实验来研究E2信号在体外和体内的传递。将检验三个亚假设：1）E2诱导的neuroP合成需要激活mGluR; 2）E2通过激活星星刺激neuroP的合成; 3）雌激素正反馈需要PR介导的室周kisspeptin神经元激活。这些研究将使用星形胶质细胞培养来研究细胞信号通路，并通过整体动物实验来验证体外结果，并将其与LH峰的调节联系起来。拟议的研究将测试一种新的机制，调节E2信息转导成神经信号，刺激GnRH释放，导致LH激增。公共卫生相关性拟议的基础研究旨在提供一个雌激素正反馈的综合模型，以了解控制下丘脑调节促黄体生成激素（LH）激增和排卵的机制，这对调节生育力和治疗不孕症都很重要。在美国，大约12%的15-44岁的女性（730万）由于由LH激增控制的排卵功能障碍而患有生育困难（疾病控制和预防中心的国家卫生统计中心）。这种类型的不孕症表现出过量的雌激素产生而不排卵，可导致多囊卵巢综合征，不规则阴道出血，代谢异常以及子宫内膜息肉，增生，甚至癌症。

DESCRIPTION (provided by applicant): Neurosteroids, steroids synthesized de novo in the brain, have been implicated in functions ranging from stress, depression, anxiety, to cognition. One neurosteroid is progesterone, a classic sex hormone involved in the regulation of reproduction. We have previously shown that peripheral estradiol (E2) increases hypothalamic neuroprogesterone (neuroP) synthesis, which initiates the luteinizing hormone (LH) surge. The LH surge triggers ovulation and the luteinization of the ruptured follicle - critical events in reproduction. Within the hypothalamus, astrocytes respond to E2 stimulation by increasing neuroP synthesis. Preliminary data point to E2-signaling that requires an interaction between membrane-associated estrogen receptor-1 (mER1) and a group 1 metabotropic glutamate receptor (mGluR1a). The resulting rise in free cytoplasmic calcium is sufficient to stimulate neuroP synthesis. Since GnRH neurons that control the LH surge do not have steroid receptors, other neurons are required to transmit steroid information to them. Kisspeptin neurons have been suggested as these intervening neurons: they project to GnRH neurons, potently excite them, and express ER1 and progesterone receptor (PR). Based on these results, we propose to test the hypothesis that estrogen positive feedback requires E2-induced neuroP synthesis involving a mER1 and mGluR1a interaction, and the activation of kisspeptin neurons. Three experiments are proposed to study E2 signaling in vitro and in vivo. Three subhypotheses will be tested: 1) E2-induced neuroP synthesis requires activation of the mGluR; 2) E2 stimulates the synthesis of neuroP by activating StAR; and 3) estrogen positive feedback requires PR-mediated activation of periventricular kisspeptin neurons. These studies will use astrocyte cultures to work out cell signaling pathways, and whole animal experiments to verify the in vitro results and tie them to regulation of the LH surge. The proposed studies will test a novel mechanism regulating the transduction of E2 information into neural signals that stimulate the release of GnRH resulting in the LH surge. PUBLIC HEALTH RELEVANCE The proposed studies at the basic level seek to provide an integrated model of estrogen positive feedback to understand the mechanisms that control hypothalamic regulation of the luteinizing hormone (LH) surge and ovulation which are important for both regulating fertility as well as treating infertility. Approximately 12% of women (7.3 million) in the United States aged 15-44 had fertility difficulties (National Center for Health Statistics of the Centers for Disease Control and Prevention) because of ovulatory dysfunction that is controlled by the LH surge. This type of infertility exhibits excess estrogen production without ovulation that can lead to polycystic ovary syndrome, irregular vaginal bleeding, metabolic abnormalities as well as endometrial polyps, hyperplasia, and even cancer.