Sex Steroids, Kisspeptin and Regulation of GnRH

描述(申请人提供)：促黄体生成素的释放受神经激素促性腺激素释放激素(GnRH)的调节。最近，通过G蛋白偶联受体GPr54传递信号的多肽Kisspeptin(KP)被发现是调节GnRH的关键成分。Kp在GnRH神经元水平上的直接作用的证据来自对表达GnRH的细胞系的解剖学和体外研究。在下丘脑中描述了两种主要的KP神经元：一种在弓状核(AN)，另一种在视前区的AVPV。Avpv KP神经元直接投射到GnRH神经元，并在雌激素诱导的LH峰时刺激GnRH神经元，而AN群体参与负反馈。这项提案将从三个方面探讨雌激素在促性腺激素激增的神经内分泌调节中的作用。目的1确定雌二醇(E2)的负反馈和正反馈作用是否通过激活KP神经元中的ERA来实现。利用一种新开发的微透析系统，将评估KP细胞特异性ERA基因敲除(KERaKO)小鼠对引起促黄体生成素神经分泌的负反馈和正反馈作用的治疗的反应。目的2将确定孕期雄激素暴露(PNA)是否导致多囊卵巢疾病的特征，在KP神经元上对E2反馈作用产生抵抗。将产生KP细胞特异性AR零突变(KARKO)小鼠，拟议的研究将确定它们是否对改变的E2负反馈和正反馈作用的雄激素编程无效。目的3将确定E2在调节GnRH神经元中调节KP GPr54信号中的作用。为了确定GnRH神经元中GPR54的激活是否介导了KP神经元对GnRH表达的生理调节，我们将评估GnRH神经元特异性GPR54基因敲除(GnRH-GPR54KO)小鼠对E2负反馈和正反馈作用的反应性。ER？在调节E2负反馈和KP介导的GnRH合成和分泌中的作用将被确定。总体而言，这些研究将系统地、分层次地评估E2在促性腺激素激增的神经内分泌控制中的作用，并确定早期雄激素暴露可能对E2反馈作用产生抵抗的机制。

DESCRIPTION (provided by applicant): The release of LH is under regulation by the neurohormone gonadotropin releasing hormone (GnRH). Recently, the peptide kisspeptin (KP) which signals through a G-protein coupled receptor, GPR54, was found to be a key component in the regulation of GnRH. Evidence for a direct role for KP at the level of the GnRH neuron comes from anatomical and in vitro studies in GnRH expressing cell lines. Two principal populations of KP neurons are described in the hypothalamus: one in the arcuate nucleus (AN) and one in a region of the preoptic area, the AVPV. The AVPV KP neurons project directly to GnRH neurons and stimulate GnRH neurons at the time of the estrogen induced LH surge, while the AN population is implicated in negative feedback. This proposal will explore the role of estrogen in the neuroendocrine regulation of the gonadotropin surge in three aims. Aim 1 will determine if the negative and positive feedback actions of estradiol (E2) are mediated by activation of ERa in KP neurons. The responses of KP cell-specific ERa knockout (KERaKO) mice to treatments that evoke negative and positive feedback actions on LH neurosecretion will be assessed using a newly developed microdialysis system. Aim 2 will determine if prenatal androgen exposure (PNA), which induces features of polycystic ovary disease, programs resistance to E2 feedback actions in KP neurons. KP cell-specific AR null mutant (KARKO) mice will be generated and proposed studies will determine if they are refractory to androgenic programming of altered negative and positive feedback actions of E2. Aim 3 will determine the role of E2 in modulating KP GPR54 signaling in the regulation of the GnRH neuron. To determine if GPR54 activation in GnRH neurons mediates the physiological regulation of GnRH expression by KP neurons, the responsiveness of GnRH neuron-specific GPR54 knockout (GnRH-GPR54KO) mice to E2 negative and positive feedback actions will be assessed. The role of ER¿ in mediating E2 negative feedback and KP mediated synthesis and secretion of GnRH will be determined. Overall, these studies will provide a systematic, hierarchical assessment of the effects of E2 in the neuroendocrine control of the gonadotropin surge, and determine the mechanisms by which early androgen exposure may program resistance to E2 feedback actions.