Ventimiglia R, Grierson J P, Gallombardo P, Sweetnam P M, Tallman J F, Geller H M
Department of Pharmacology, University of Medicine and Dentistry of New Jersey, Robert Wood Johnson Medical School, Piscataway, NJ 08854.
Neurosci Lett. 1990 Jul 31;115(2-3):131-6. doi: 10.1016/0304-3940(90)90443-d.
gamma-Aminobutyric acid (GABA) is the major inhibitory transmitter in the mammalian central nervous system (CNS) and an understanding of the development of receptors for this compound is of considerable interest. In this study, 3 monoclonal antibodies directed against the GABAA/benzodiazepine (GABA/BDZ) receptor were utilized in immunocytochemical experiments to localize receptor sites on neurons in dissociated cultures from fetal rat hypothalamus. Immunoreactivity was restricted to distinct patches on the plasma membrane of neurons. Analogous patches were observed on the surface of type 1 astrocytes, but not on type 2 astrocytes or oligodendrocytes. In membrane extracts from whole brain these antibodies reacted with two proteins (50 and 55 kDa) whereas extracts of cultured astrocytes yielded a single protein of approximately 63 kDa. Thus the identity of the glial protein remains unclear, but this study provides evidence for the presence of shared epitopes of the GABA/BDZ-receptor on both neurons and glia, and suggests that the astrocytic receptors may be important to nervous system function. Moreover it indicates that in vitro GABA/BDZ-receptors may form aggregates which would account for the restricted patterns of GABA sensitivity reported in some electrophysiological studies.
γ-氨基丁酸（GABA）是哺乳动物中枢神经系统（CNS）中的主要抑制性神经递质，对该化合物受体的发育进行了解具有相当大的研究价值。在本研究中，3种针对GABAA/苯二氮䓬（GABA/BDZ）受体的单克隆抗体被用于免疫细胞化学实验，以定位来自胎鼠下丘脑的解离培养物中神经元上的受体位点。免疫反应性局限于神经元质膜上的不同斑块。在1型星形胶质细胞表面观察到类似的斑块，但在2型星形胶质细胞或少突胶质细胞表面未观察到。在全脑的膜提取物中，这些抗体与两种蛋白质（50和55 kDa）发生反应，而培养的星形胶质细胞提取物产生一种约63 kDa的单一蛋白质。因此，胶质蛋白的身份仍不清楚，但这项研究为神经元和胶质细胞上存在GABA/BDZ受体的共同表位提供了证据，并表明星形胶质细胞受体可能对神经系统功能很重要。此外，它表明体外GABA/BDZ受体可能形成聚集体，这可以解释一些电生理研究中报道的GABA敏感性受限模式。
