Clark A S, Myers M, Robinson S, Chang P, Henderson L P
Department of Psychology, Dartmouth College, Hanover, NH 03755, USA.
Proc Biol Sci. 1998 Oct 7;265(1408):1853-9. doi: 10.1098/rspb.1998.0512.
Transmission mediated by gamma-aminobutyric acid type A (GABAA) receptors expressed within the medial preoptic area (mPOA) and the ventromedial nucleus (VMN) of the hypothalamus is known to play critical, but contrasting, roles in regulating steroid-dependent sexual behaviours in rats. Previous studies have demonstrated a striking dichotomy in receptor composition between the two regions with regard to gamma, but not alpha or beta, subunit expression. To test if gonadal steroids regulate the expression of the gamma subunit genes within the mPOA and the VMN, in situ hybridization analysis for messenger RNAs encoding the gamma 1, gamma 2Short (gamma 2S) and gamma 2Long (gamma 2L) subunits was done in gonadectomized male and female rats and in gonadally intact females over the oestrous cycle. No significant differences in the expression of the gamma subunit mRNAs were observed in gonadectomized male versus female rats. Significant effects of gonadal state in female rats were observed for gamma 1 mRNA levels in the mPOA and gamma 2L levels in the VMN. These data demonstrate that gonadal hormones exert activational control of expression of GABAA receptor gamma subunit mRNAs and suggest that differences in receptor structure may contribute to the functional modulation of female sexual behaviours mediated by GABAergic transmission in these regions.
由下丘脑内侧视前区（mPOA）和腹内侧核（VMN）中表达的A型γ-氨基丁酸（GABAA）受体介导的传递，在调节大鼠类固醇依赖性性行为中发挥着关键但相反的作用。先前的研究表明，就γ亚基表达而言，这两个区域在受体组成上存在显著差异，而α或β亚基表达则无差异。为了测试性腺类固醇是否调节mPOA和VMN内γ亚基基因的表达，对去势的雄性和雌性大鼠以及处于发情周期的性腺完整雌性大鼠进行了原位杂交分析，以检测编码γ1、γ2短亚型（γ2S）和γ2长亚型（γ2L）亚基的信使RNA。在去势的雄性和雌性大鼠中，未观察到γ亚基mRNA表达的显著差异。在雌性大鼠中，观察到性腺状态对mPOA中γ1 mRNA水平和VMN中γ2L水平有显著影响。这些数据表明，性腺激素对GABAA受体γ亚基mRNA的表达具有激活调控作用，并表明受体结构的差异可能有助于这些区域中由GABA能传递介导的雌性性行为的功能调节。
