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，焦虑到认知等功能。黄体酮是一种神经类固醇，它是一种典型的性激素，与生殖调节有关。我们之前已经表明，外周雌二醇（E2）增加下丘脑神经孕酮（neuroP）合成，从而启动黄体生成素（LH）激增。黄体生成素激增触发排卵和破裂卵泡的黄体化，这是生殖中的关键事件。在下丘脑内，星形胶质细胞通过增加神经p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 （mER1）和1组代谢性谷氨酸受体（mGluR1a）之间的相互作用。由此产生的游离细胞质钙的增加足以刺激神经p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干预神经元：它们投射到GnRH神经元，有效地激发它们，并表达ER1和孕激素受体（PR）。基于这些结果，我们提出验证雌激素正反馈需要e2诱导的神经p合成，包括mER1和mGluR1a的相互作用，以及kisspeptin神经元的激活。我们提出了三个实验来研究E2信号在体内和体外的作用。将测试三个子假设：1)e2诱导的神经p合成需要激活mGluR；2) E2通过激活StAR刺激neuroP的合成；3)雌激素正反馈需要pr介导的心室周围kisspeptin神经元的激活。这些研究将使用星形胶质细胞培养来确定细胞信号通路，并使用全动物实验来验证体外结果，并将其与LH激增的调节联系起来。这些研究将测试一种调节E2信息转化为神经信号的新机制，刺激GnRH的释放，导致LH激增。基础水平的研究旨在提供雌激素正反馈的综合模型，以了解控制下丘脑对黄体生成素（LH）的调节和排卵的机制，这对调节生育和治疗不孕症都很重要。在美国，年龄在15-44岁的女性中大约有12%（730万）有生育困难（疾病控制和预防中心的国家卫生统计中心），原因是由黄体生成素激增控制的排卵功能障碍。这种类型的不孕症表现为雌激素分泌过多而不排卵，可导致多囊卵巢综合征，阴道不规则出血，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.