Demonstration that the neural network for the LHRH surge generator is distinct from that for the pulse generator.

本研究用电生理学、免疫组织化学和分子生物学方法，揭示了两种不同的LHRH神经元亚群参与了促性腺激素分泌的两种不同方式，即排卵前促性腺激素分泌和搏动性分泌。1.在大鼠中，位于视前区的LHRH神经元以GABA神经元为雌激素反应元件，构成LHRH浪涌发生器。生成器可能通过神经元通路从视交叉上核(SCN)接收时钟信息。雌激素通过在转录水平影响GABA神经元活性，增加谷氨酸脱氢酶活性，并对LHRH神经元产生抑制作用。在发情前期的下午，GABA神经元介导的抑制作用被某种程度的破坏，使LHRH的分泌激增。我们目前正在研究GABA神经元对LHRH神经元的干扰抑制机制，以及什么样的神经元将时钟信息从SCN发送到电涌发生器。2.LHRH脉冲产生神经系统位于下丘脑内侧基底部的LHRH神经元组成LHRH脉冲发生器，阿片类神经元作为雌激素负反馈效应的中介。我们目前的研究重点是LHRH神经元同步放电的机制是什么。

In the present study, we revealed, by means of electrophysiological, immunohistochemical and molecular biological methods, that two distinct subgroups of LHRH neurons are involved in the control of two different modes of gonadotropin secretion, i.e., one is for preovulatory surge secretion and the other for pulsatile secretion, .1.LHRH surge generating neuronal systemIn the rat, LHRH neurons located in the preoptic area constitutes the LHRH surge generator with GABA neurons as an estrogen-responsive element. The generator receives the clock information from the suprachiasmatic nucleus (SCN) probably through neuronal pathways. Estrogen affects GABA neuronal activity by acting at mRNA transcriptional level and increasing glutamic acid dehydrogenase, and exerts inhibition on LHRH neurons. The inhibition mediated by GABA neurons is disrupted somehow in the afternoon of proestrus to make the surge of LHRH secretion. We are currently studying what is the mechanism for disrupting inhibition by GABA neurons on LHRH neurons and what kind of neurons send clock information from the SCN to the surge generator.2.LHRH pulse generating neuronal systemLHRH neurons located in the mediobasal hypothalamus constitute the LHRH pulse generator with opioid neurons as a mediator of negative feedback effects of estrogen. We are focussing the current study on what is the mechanism of synchronizing firing in LHRH neurons.