Kawahara F, Saito H, Katsuki H
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Neurosci Lett. 1993 Sep 17;160(1):45-8. doi: 10.1016/0304-3940(93)90913-6.
The suprachiasmatic nucleus (SCN) is considered to be an endogenous circadian pacemaker. Previous studies have suggested functional roles of gamma-aminobutyric acid (GABA) in the control of circadian rhythms. In this study, the responses to applied GABA in cultured SCN neurons dissociated from postnatal rat hypothalamus were investigated using whole-cell voltage-clamp techniques. GABA and muscimol induced a large current response (EC50 values 5.3 and 1.6 microM, respectively), which was blocked by the GABAA antagonist bicuculline. This current response was also blocked by Zn2+ (0.5-50 microM) in a concentration-dependent manner, but was not potentiated by diazepam (10 microM) or ethanol (21 mM). These characteristics seem to correspond to those of GABAA receptors that lack gamma-type subunits.
视交叉上核（SCN）被认为是内源性昼夜节律起搏器。先前的研究表明γ-氨基丁酸（GABA）在昼夜节律控制中具有功能作用。在本研究中，使用全细胞膜片钳技术研究了从新生大鼠下丘脑分离的培养SCN神经元对施加的GABA的反应。GABA和蝇蕈醇诱导了大的电流反应（EC50值分别为5.3和1.6 microM），该反应被GABAA拮抗剂荷包牡丹碱阻断。这种电流反应也被Zn2+（0.5 - 50 microM）以浓度依赖性方式阻断，但未被地西泮（10 microM）或乙醇（21 mM）增强。这些特征似乎与缺乏γ型亚基的GABAA受体的特征相符。
