Sperk G, Schwarzer C, Tsunashima K, Fuchs K, Sieghart W
Department of Pharmacology, University of Innsbruck, Austria.
Neuroscience. 1997 Oct;80(4):987-1000. doi: 10.1016/s0306-4522(97)00146-2.
The GABA(A) receptor is a ligand-operated chloride channel. It has a pentameric structure. In mammalian brain different subunits are recruited from four gene subfamilies. Using immunocytochemistry, we investigated the distribution of the 13 GABA(A) receptor subunits in the hippocampus of the rat. GABA(A) receptor subunits were heterogeneously distributed within different hippocampal subfields. High concentrations of alpha1-, alpha2-, alpha4-, beta3-, gamma2- and delta-immunoreactivities were observed within the molecular layer of the dentate gyrus, representing the dendritic area of the granule cells. In the hippocampus proper, the predominant GABA(A) receptor subunits were alpha1, alpha2, alpha5, beta3 and gamma2 that were located throughout the strata radiatum and oriens of CA1 to CA3. Immunocytochemical staining was there less prominent for alpha4-, beta1-, beta2- gamma3- and delta- subunits. In the hippocampus proper, the beta1 subunit was preferentially located in CA2. The alpha4- and delta-subunits were somewhat more abundant in CA1 than in CA3. Numerous local circuit neurons in the hippocampus proper and the hilus of the dentate gyrus contained alpha1-, beta2-, gamma2- and/or delta-subunits. Alpha3 and gamma1 were present only in minute amounts and no alpha6-IR was detected in the hippocampal formation. The distribution of the GABA(A) receptor subunits indicates the existence of heterogenously constituted GABA(A) receptor complexes within various hippocampal subfields, which may exert different physiological or pharmacological properties upon stimulation by GABA or its agonists.
GABA(A)受体是一种配体门控氯离子通道。它具有五聚体结构。在哺乳动物大脑中，不同亚基来自四个基因亚家族。我们利用免疫细胞化学方法研究了大鼠海马中13种GABA(A)受体亚基的分布。GABA(A)受体亚基在不同的海马亚区呈异质性分布。在齿状回分子层观察到高浓度的α1、α2、α4、β3、γ2和δ免疫反应性，该层代表颗粒细胞的树突区域。在海马本部，主要的GABA(A)受体亚基是α1、α2、α5、β3和γ2，它们分布在CA1至CA3的辐射层和原层。α4、β1、β2、γ3和δ亚基的免疫细胞化学染色在海马本部不太明显。在海马本部，β1亚基优先位于CA2区。α4和δ亚基在CA1区比在CA3区略丰富。海马本部和齿状回门区的许多局部回路神经元含有α1、β2、γ2和/或δ亚基。α3和γ1仅微量存在，在海马结构中未检测到α6免疫反应性。GABA(A)受体亚基的分布表明在不同的海马亚区存在异质性组成的GABA(A)受体复合物，这些复合物在受到GABA或其激动剂刺激时可能发挥不同的生理或药理特性。
