Lukasiewicz P D
Department of Ophthalmology & Visual Sciences, Washington University School of Medicine, St. Louis, MO 63110-1093, USA.
Mol Neurobiol. 1996 Jun;12(3):181-94. doi: 10.1007/BF02755587.
In the central nervous system (CNS), the inhibitory transmitter GABA interacts with three subtypes of GABA receptors, type A, type B, and type C. Historically, GABA receptors have been classified as either the inotropic GABAA receptors or the metabotropic GABAB receptors. Over the past 10 yr, studies have shown that a third class, called the GABAC receptor, also exists. GABAC receptors are found primarily in the vertebrate retina and to some extent in other parts of the CNS. Although GABAA and GABAC receptors both gate chloride channels, they are pharmacologically, molecularly, and functionally distinct. The rho subunit of the GABAC receptor, which has about 35% amino acid homology to GABAA receptor subunits, was cloned from the retina and, when expressed in Xenopus oocytes, has properties similar to retinal GABAC receptors. There are probably distinct roles for GABAC receptors in the retina, because they are found on only a subset of neurons, whereas GABAA receptors are ubiquitous. This article reviews recent electrophysiological and molecular studies that have characterized the unique properties of GABAC receptors and describes the roles that these receptors may play in visual information processing in the retina.
在中枢神经系统（CNS）中，抑制性递质γ-氨基丁酸（GABA）与三种GABA受体亚型相互作用，即A型、B型和C型。从历史上看，GABA受体被分类为促离子型GABAA受体或促代谢型GABAB受体。在过去10年中，研究表明还存在第三种类型，即GABAC受体。GABAC受体主要存在于脊椎动物视网膜中，在中枢神经系统的其他部分也有一定程度的存在。尽管GABAA和GABAC受体都控制氯离子通道，但它们在药理学、分子学和功能上是不同的。GABAC受体的rho亚基与GABAA受体亚基具有约35%的氨基酸同源性，它是从视网膜中克隆出来的，当在非洲爪蟾卵母细胞中表达时，具有与视网膜GABAC受体相似的特性。GABAC受体在视网膜中可能具有独特的作用，因为它们仅存在于一部分神经元上，而GABAA受体则普遍存在。本文综述了最近的电生理学和分子学研究，这些研究表征了GABAC受体的独特特性，并描述了这些受体在视网膜视觉信息处理中可能发挥的作用。
