GABA对大鼠下丘脑正中隆起LHRH释放调节的研究

本研究应用大鼠下丘脑正中隆起(ME),观察 γ-氨基丁酸(GABA)和去甲肾上腺素(NA)对下丘脑促黄体生成激素释放激素(LHRH)神经元末梢分泌作用的影响。结果发现:GABA(10~(-6)mol/L)可显著促进 ME 的 LHRH 和 NA 的释放,即 LHRH 释放量由27.3±2.5pg/100ul 增加至150.4±27.9pg/100μl;NA 释放量由50.9±4.2pg/100μl 增加至105.5±19.1pg/100ul,两者与对照组相比有显著差异(P<0.01)。GABA 这些作用可被受体拮抗剂荷包牡丹碱(Bicuculline)所翻转。当荷包牡丹碱和 GABA(10~(-6)mol/L)同时存在于 ME 的培灌液中,LHRH 的分泌量下降为18.2±1.9pg/100μl,而 NA 分泌量下降为43.9±3.4pg/100μl。在内源性 NA 被利血平耗竭时,LHRH 的释放量仅增加26.5%,而 GABA 能使正常大鼠 LHRH 释放量增加451.9%。本研究提示:GABA 可促进下丘脑 ME 释放 LHRH,这一作用可能通过 NA 中介。

A STUDY OF THE REGULATORY ROLE OF GABA ON THE LHRH RELEASE IN THE MEDIAN EMINENCE OF RATS

The present study was undertaken to observe the effect of GABA and NA on LHRH neuronal terminals in the median eminence (ME). The results showed that GABA (10(-6) mol/L) significantly increased LHRH and NA release from ME, i.e., respectively from 27.3 +/- 2.5 pg/100 microliters to 150.4 +/- 27.9 pg/100 microliters and from 50.9 +/- 4.2 pg/100 microliters to 105.5 +/- 19.1 pg/100 microliters (both P less than 0.01 vs control group). These effects of GABA could be blocked by bicuculline. When bicuculline and GABA (10(-6) mol/L) were added into the ME, the secretion of LHRH decreased to 18.2 +/- 1.9 pg/100 microliters and that of NA to 43.9 +/- 3.4 pg/100 microliters. The effect of GABA on LHRH release may be mediated by NA. When endogenous NA was depleted by reserpine, GABA increased LHRH secretion only by 26.5% instead of 451.9% as in the normal animal.