Cubells J F, Walkley S U, Makman M H
Department of Neuroscience, Albert Einstein College of Medicine, Bronx, NY 10461.
Brain Res. 1988 Aug 16;458(1):82-90. doi: 10.1016/0006-8993(88)90498-2.
gamma-Aminobutyric acid (GABA) is an inhibitory transmitter found in the retinae of mammals largely within certain amacrine cells. In previous studies from this laboratory, subcutaneous administration to rats of gabaculine, an enzyme-activated irreversible inhibitor of gamma-aminobutyric acid (GABA)-transaminase, produced large, rapid and long-lasting increases in levels of retinal GABA. We employed immunocytochemistry to determine whether such changes in the levels of retinal GABA are accompanied by changes in the cellular distribution of GABA. Using a recently developed antiserum to a GABA-protein conjugate, and the peroxidase-antiperoxidase method, we examined retinae from control rats and from rats 2 or 8 h after administration of 10 mg/kg gabaculine. From previous work, retinal levels of GABA were respectively elevated 3- or 6-fold at those postgabaculine times. In the present study, marked changes in the distribution of GABA-like immunoreactivity (GABA-LIR) were apparent by 2 h after injection of gabaculine, and were more striking at 8 h postgabaculine. The pattern of staining for GABA-LIR strongly suggested that much of the GABA in gabaculine-treated retinae was within Müller glial cells. That observation provides evidence for the importance of those cells in the uptake and degradation of GABA after its release from retinal neurons.
γ-氨基丁酸（GABA）是一种抑制性神经递质，在哺乳动物视网膜中主要存在于某些无长突细胞内。在本实验室先前的研究中，给大鼠皮下注射γ-氨基丁酸（GABA）转氨酶的酶激活不可逆抑制剂加巴喷丁，可使视网膜GABA水平迅速大幅且持久升高。我们采用免疫细胞化学方法来确定视网膜GABA水平的这种变化是否伴随着GABA细胞分布的改变。使用最近开发的针对GABA-蛋白质偶联物的抗血清以及过氧化物酶-抗过氧化物酶方法，我们检查了对照大鼠以及注射10 mg/kg加巴喷丁后2小时或8小时的大鼠的视网膜。根据先前的研究，在加巴喷丁注射后的那些时间点，视网膜GABA水平分别升高了3倍或6倍。在本研究中，注射加巴喷丁后2小时，GABA样免疫反应性（GABA-LIR）的分布就出现了明显变化，在加巴喷丁注射后8小时更为显著。GABA-LIR的染色模式强烈表明，加巴喷丁处理的视网膜中的大部分GABA存在于穆勒胶质细胞内。这一观察结果为这些细胞在GABA从视网膜神经元释放后对其摄取和降解中的重要性提供了证据。
