Sex Steroids, Kisspeptin and Regulation of GnRH

描述（由申请方提供）：LH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GPR 54发出信号的肽Kisspeptin（KP）被发现是GnRH调节的关键组分。KP在GnRH神经元水平的直接作用的证据来自GnRH表达细胞系的解剖学和体外研究。KP神经元的两个主要群体被描述在下丘脑：一个在弓状核（AN）和一个在视前区的一个区域，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群体涉及负反馈。本研究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：研究雌二醇（E2）的负反馈和正反馈作用是否是由KP神经元中ER α的激活介导的。将使用新开发的微透析系统评估KP细胞特异性ER α敲除（KERaKO）小鼠对引起LH神经分泌负反馈和正反馈作用的治疗的反应。目的2将确定是否产前雄激素暴露（PNA），诱导多囊卵巢疾病的特点，程序在KP神经元E2反馈行动的阻力。将产生KP细胞特异性AR无效突变（KARKO）小鼠，并且所提出的研究将确定它们是否对E2的改变的负反馈和正反馈作用的雄激素编程难治。目的3将确定E2在调节GnRH神经元的KP GPR 54信号中的作用。为了确定GnRH神经元中的GPR 54活化是否介导KP神经元对GnRH表达的生理调节，将评估GnRH神经元特异性GPR 54敲除（GnRH-GPR 54 KO）小鼠对E2负反馈和正反馈作用的响应性。ER在介导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，这些研究将提供一个系统的，分层评估E2在促性腺激素激增的神经内分泌控制的影响，并确定早期雄激素暴露可能程序抵抗E2反馈作用的机制。

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.