Ikeda Y, Nishiyama N, Saito H, Katsuki H
Department of Chemical Pharmacology, Faculty of Pharmaceutical Sciences, University of Tokyo, Japan.
Brain Res Dev Brain Res. 1997 Feb 20;98(2):253-8. doi: 10.1016/s0165-3806(96)00183-6.
In order to clarify the functional role of gamma-aminobutyric acid (GABA) in developing brain, we investigated the effect of GABA on the survival of embryonic rat striatal neurons in dissociated cell culture. Chronic exposure of striatal cultures to GABA resulted in a significant increase in the number of surviving neurons. The effect of GABA was concentration-dependent (1-1000 microM) and was blocked by a GABAA receptor antagonist, bicuculline (100 microM), or a GABAA chloride channel blocker, picrotoxin (100 microM), but not by a GABAB receptor antagonist, 2-hydroxysaclofen (100 microM). In addition, the GABAA receptor agonist muscimol mimicked the effect of GABA, promoting cell survival in a concentration-dependent manner (0.01-100 microM), while the GABAB receptor agonist baclofen (up to 100 microM) had no significant effect. The GABA-induced enhancement of neuronal survival was suppressed by the L-type voltage-dependent Ca2+ channel blockers nifedipine (1-3 microM) and nicardipine (1-5 microM). Protein kinase inhibitors, H-7 (10-30 microM) or genistein (3 microM), also suppressed GABA-induced enhancement of neuronal survival. These results suggest that stimulation of GABAA receptors enhances survival of embryonic striatal neurons, and that the effect is mediated by Ca2+ influx through L-type voltage-dependent Ca2+ channels, initiating intracellular signaling cascades that involve activation of H-7- and genistein-sensitive protein kinases.
为了阐明γ-氨基丁酸（GABA）在发育中的大脑中的功能作用，我们研究了GABA对离体培养的胚胎大鼠纹状体神经元存活的影响。将纹状体培养物长期暴露于GABA导致存活神经元数量显著增加。GABA的作用呈浓度依赖性（1 - 1000微摩尔），并被GABAA受体拮抗剂荷包牡丹碱（100微摩尔）或GABAA氯化物通道阻滞剂印防己毒素（100微摩尔）阻断，但不被GABAB受体拮抗剂2-羟基喹喔啉酸（100微摩尔）阻断。此外，GABAA受体激动剂蝇蕈醇模拟了GABA的作用，以浓度依赖性方式（0.01 - 100微摩尔）促进细胞存活，而GABAB受体激动剂巴氯芬（高达100微摩尔）则无显著作用。GABA诱导的神经元存活增强被L型电压依赖性Ca2+通道阻滞剂硝苯地平（1 - 3微摩尔）和尼卡地平（1 - 5微摩尔）抑制。蛋白激酶抑制剂H-7（10 - 30微摩尔）或染料木黄酮（3微摩尔）也抑制了GABA诱导的神经元存活增强。这些结果表明，刺激GABAA受体可增强胚胎纹状体神经元的存活，且该作用由通过L型电压依赖性Ca2+通道的Ca2+内流介导，引发涉及激活对H-7和染料木黄酮敏感的蛋白激酶的细胞内信号级联反应。
