Electrophysiological identification of LHRH neurons that are involved in the LH surge induced by positive feedback action of estrogen.

我们提出的假说是，参与雌激素正反馈作用引起的黄体生成素释放(黄体生成素峰)的LHRH神经元不同于卵巢切除条件下参与黄体生成素脉冲性释放的神经元。本研究旨在利用多单位活动(MUA)记录技术进一步研究这一假说。研究结果如下：1.研究结果。LHRH神经元表现为MUA间歇性升高，伴随着促黄体生成素脉冲，参与了雌激素负反馈作用控制的促黄体生成素的基础释放。我们将这些LHRH神经元称为I型。雌激素对这些神经元的负反馈作用是由阿片肽能神经元介导的。此外，这些I型神经元的间歇循环放电是戊巴比妥敏感的。与I型神经元不同的是：(1)去卵巢大鼠LHRH神经元不出现MUA，MUA随LH脉冲间歇性增加。(2)涉及II型LHRH神经元的机制和对雌激素正反馈效应的抑制作用与阿片肽能神经元无关，但(3)对戊巴比妥钠敏感。上述结果提示，中枢神经系统中的LHRH神经元有两种功能亚型，即I型和II型。即使用MUA技术也无法记录到II型神经元的电活动。似乎有必要将电极放置在更正面的部位。

We have raised the hypothesis that the LHRH neurons that are involved in the phasic release of LH (LH surge) induced by positive feedback action of estrogen are different from those that are involved in the pulsatile release of LH occurring in the ovariectomized conditions. The present study was undertaken to investigate this hypothesis further using the multiunit activity (MUA)recording technique. The results are as follows.1. The LHRH neurons showing MUA which increases intermittently in association with LH pulses are involved in the basal release of LH controlled by negative feedback effect of estrogen. We have called these LHRH neurons Type I. The negative feedback effect of estrogen to these neurons are mediated by opioid peptidergic neurons. Further, the intermittent, cyclic firing of these Type I neurons is pentobarbital sensitive.2. We called those LHRH neurons that are involved in phasic LH release (LH surge) Type II. Those neurons are different from Type I in some aspects as follows : (1) These LHRH neurons do not show MUA which increases intermittently in association with LH pulses in ovariectomized rats. (2) The mechanism that involves Type II LHRH neurons and acts to control LH surge in response to positive feedback effects of estrogen dose not involve opioid peptidergic neurons, but (3) is sensitive to pentobarbital.In conclusion, the results have suggested that LHRH neurons in the CNS have two functional subtypes, arbitrarily called Type I and Type II. The electrical activity of Type II neurons could not be recorded, even by the MUA technique. It seems necessary to place the electrodes at the more frontal site.