Defining the neurophysiologic mechanisms engaged by estradiol feedback in regulating reproductive neuroendocrine function

项目摘要 15-20%的美国夫妇与不孕问题作斗争。女性不孕症最常见的原因 是无排卵，因此了解如何控制排卵是至关重要的，以协助形成和增长 改善我国的生殖健康，并增加我们对 生殖排卵是由黄体生成素（LH）分泌模式的转换刺激的， 间歇性持续释放（LH激增）。在低生理浓度下，雌二醇调节 负反馈（negative feedback）在卵泡期结束时雌二醇持续升高（ 啮齿类动物）刺激LH峰的发作（正反馈）。在大多数哺乳动物中， 通过雌二醇诱导的促性腺激素释放激素（GnRH）分泌激增和伴随的 垂体对这种激素的反应增加。虽然GnRH输入模式的改变不需要 在人类中诱导LH激增，在恒河猴中观察到排卵前和雌二醇诱导的激增 这表明GnRH激增可能在灵长类动物的典型生殖功能中也起作用。的 这个提议的目的是增加我们对驱动这种转变的中枢神经机制的认识。 从负反馈到正反馈，并确定这些机制是否是雌二醇- 敏感GnRH神经元本身不表达可检测水平的雌激素受体α（ERα），因此 在这一过程中需要雌激素敏感的传入神经。 假设是雌二醇正反馈的关键部位，因为它含有共表达两者的神经元 kisspeptin是GnRH分泌的有效激活剂，ERα、AVPV kisspeptin神经元表达更多kisspeptin 并且在正反馈期间以雌二醇依赖的方式更活跃，这表明增加了 来自这些细胞的信号有助于驱动正反馈。我们对如何做到这一点的理解仍然存在差距 雌二醇激活AVPV kisspeptin神经元，并调节其kisspeptin和快突触的传递。 GnRH神经元的信号我们假设雌二醇调节钾电流和突触特性， AVPV神经元在正反馈过程中增加其活动并随后传递兴奋性 GnRH神经元的信号在两个目标中，我们将测量钾电流，功能性突触连接 和可塑性，以及AVPV kisspeptin神经元的kisspeptin释放，以确定这些参数是否 在周期中通过比较间情期和 发情前期小鼠为了研究哪些机制是由雌二醇特异性调节的，我们将利用一个小鼠模型， 雌二醇诱导的LH峰模型。这些研究将有助于提供机械的见解，这将有助于建立在 我们对雌二醇调节生殖的神经生理机制的理解 神经内分泌输出这些知识可以为新的生育治疗以及针对 其他雌二醇调节的中枢过程，如焦虑、神经保护和对压力的反应。

Project Summary 15-20% of American couples struggle with infertility problems. The most common cause of infertility in women is anovulation, thus understanding how ovulation is controlled is critical for assisting the formation and growth of families, improving the reproductive health of our country, and increasing our fundamental knowledge of reproduction. Ovulation is stimulated by a switch in the pattern of luteinizing hormone (LH) secretion from episodic to continuous release (LH surge). At low physiological concentrations, estradiol regulates episodic secretion (negative feedback). Sustained elevation of estradiol at the end of the follicular phase (proestrus in rodents) stimulates the onset of the LH surge (positive feedback). In most mammals, the LH surge is triggered by an estradiol-induced surge in gonadotropin-releasing hormone (GnRH) secretion and an accompanying increase in pituitary response to this hormone. Although a shift in the pattern of GnRH input is not needed to induce an LH surge in humans, both pre-ovulatory and estradiol-induced surges have been observed in rhesus macaques, suggesting a GnRH surge likely plays a role in typical reproductive function in primates as well. The goals of this proposal are to increase our knowledge of the central neuronal mechanisms driving the transition from negative to positive feedback during the cycle, and to determine if these mechanisms are estradiol- sensitive. GnRH neurons themselves do not express detectable levels of estrogen receptor α (ERα), thus estradiol-sensitive afferents are needed in this process The anteroventral-periventricular nucleus (AVPV) is postulated to be a critical site for estradiol positive feedback as it contains neurons that co-express both kisspeptin, a potent activator of GnRH secretion, and ERα, AVPV kisspeptin neurons express more kisspeptin and are more active in an estradiol-dependent manner during positive feedback, suggesting increased signaling from these cells helps drive positive feedback. There are still gaps in our understanding of how estradiol activates AVPV kisspeptin neurons and modulates their transmission of kisspeptin and fast synaptic signals to GnRH neurons. We hypothesize estradiol modulates potassium currents and synaptic properties of AVPV neurons during positive feedback to increase their activity and subsequent transmission of excitatory signals to GnRH neurons. In two Aims, we will measure potassium currents, functional synaptic connectivity and plasticity, and kisspeptin release by AVPV kisspeptin neurons to determine if these parameters are modified by the transition from negative to positive feedback during the cycle by comparing diestrous and proestrous mice. To examine which mechanisms are specifically regulated by estradiol, we will utilize a murine estradiol-induced LH surge model. These studies will help provide mechanistic insights that will help build on our understanding of the neurophysiological mechanisms by which estradiol regulates reproductive neuroendocrine output. This knowledge can inform new fertility treatments as well as treatments targeted at other estradiol-modulated central processes, such as anxiety, neuroprotection, and response to stress.