Cellular and molecular bases for rhythmic GnRH release

描述（由申请人提供）：促性腺激素释放激素（GnRH）的偶发性释放形成了生殖中枢调节的最终共同途径。因此，了解这种释放背后的机制，通过为人类以及重要的食物和纤维生产物种的生育和避孕提供新的策略，对人类健康有直接的好处。在四个特定的目标中，将使用最先进的电生理方法来研究GnRH偶发性释放的内在和网络特性。目的1将检查单个GnRH神经元固有的离子电导率，这是动作电位产生的基础。这些电导如何在单个神经元中随着时间的推移而改变，以及它们如何在生殖状态之间发生变化，将被确定。目的2将检查GnRH神经元中动作电位放电引起的电压和钙激活电导。这些电导在动作电位峰值和最终动作电位爆发之间的差异将被确定，以解决电导如何改变以停止这些细胞的放电的问题。目标3将测试GnRH神经元如何相互沟通。先前的研究表明，这些神经元可以使用GnRH和谷氨酸作为递质。对GnRH的反应是剂量依赖性的，低剂量抑制和高剂量刺激GnRH神经元活动。这些差异反应背后的信号通路将通过特定GnRH受体- g蛋白组合的配体进行测试。GnRH神经元之间的化学突触和电偶联将通过双重记录和协调探索的位置进行检查。第四个目标将探索GnRH神经元之间的相互作用以及它们所在的局部网络。最近的研究表明，GnRH神经元不仅释放激素控制下游垂体前叶，而且还局部调节其gaba能传入。我们将探索GABA和谷氨酸神经元以及包裹GnRH神经元的星形胶质细胞之间的其他局部网络相互作用。星形胶质细胞在协调GnRH神经元活动中的可能作用将被解决。综上所述，这些研究将深入了解导致偶发性GnRH释放的内在和网络特性。

DESCRIPTION (provided by applicant): Episodic release of gonadotropin-releasing hormone (GnRH) forms the final common pathway for the central regulation of reproduction. As such, understanding the mechanisms underlying this release has direct benefits to human health by providing new strategies for fertility and contraception in humans and in important food and fiber producing species. State-of-the-are electrophysiological approaches will be used to investigate the intrinsic and network properties that underlie episodic GnRH release in four specific aims. Aim 1 will examine the ionic conductances intrinsic to individual GnRH neurons that underlie initiation of action potential generation. How these conductances are modified over time in an individual neuron and how they change between reproductive state will be determined. Aim 2 will examine the voltage- and calcium-activated conductances induced by action potential firing in GnRH neurons. Differences in these conductances between action potential spikes and following the final action potential in a burst will be determined to address the question of how conductances change to stop firing of these cells. Aim 3 will test how GnRH neurons communicate with one another. Previous work shows that these neurons can use GnRH and glutamate as transmitters. The response to GnRH is dose-dependent with low doses inhibiting and high doses stimulating GnRH neuron activity. The signaling pathways underlying these differential responses will be tested with ligands that signal through specific GnRH receptor-Gprotein combinations. Chemical synaptic and electortonic coupling between GnRH neurons will be examined with dual recordings and the site of coordination explored. The fourth aim will explore interactions between GnRH neurons the local network in which they reside. Recent data indicate GnRH neurons not only release hormone to contol the downstream anterior pituitary, but also locally to regulate their GABAergic afferents. We wll explore other local network interactions with GABA and glutamate neurons, and with the astrocytes that ensheath GnRH neurons. A possible role for astrocytes in coordinating GnRH neuron activity will be addressed. Together these studies will provide insight into both the intrinsic and network properties leading to episodic GnRH release.