Connaughton V P, Behar T N, Liu W L, Massey S C
Laboratory of Neurophysiology, National Institute of Neurological Diseases and Stroke, National Institutes of Health, Bethesda, MD 20892-4066, USA.
Vis Neurosci. 1999 May-Jun;16(3):483-90. doi: 10.1017/s0952523899163090.
The patterns of glutamate, gamma-aminobutyric acid (GABA), and glycine distribution in the zebrafish retina were determined using immunocytochemical localization of antisera at the light-microscope level. The observed GABA immunoreactivity (GABA-IR) patterns were further characterized using antibodies to both isoforms of glutamic acid decarboxylase (GAD65 and GAD67), the synthetic enzyme for GABA. Glutamate-IR was observed in all retinal layers with photoreceptors, bipolar cells, and ganglion cells prominently labeled. Bipolar cells displayed the most intense glutamate-IR and bipolar cell axon terminals were clearly identified as puncta arranged in layers throughout the inner plexiform layer (IPL). These findings suggest the presence of multiple subtypes of presumed OFF- and ON-bipolar cells, including some ON-bipolar cells characterized by a single, large (9 microm X 6 microm) axon terminal. GABA-, GAD-, and glycine-IR were most intense in the inner retina. In general, the observed labeling patterns for GABA, GAD65, and GAD67 were similar. GABA- and GAD-IR were observed in a population of amacrine cells, a few cells in the ganglion cell layer, throughout the IPL, and in horizontal cells. In the IPL, both GABA- and GAD-IR structures were organized into two broad bands. Glycine-IR was observed in amacrine cells, interplexiform cells, and in both plexiform layers. Glycine-positive terminals were identified throughout the IPL, with a prominent band in sublamina 3 corresponding to an immunonegative region observed in sections stained for GAD and GABA. Our results show the distribution of neurons in the zebrafish retina that use glutamate, GABA, or glycine as their neurotransmitter. The observed distribution of neurotransmitters in the inner retina is consistent with previous studies of other vertebrates and suggests that the advantages of zebrafish for developmental studies may be exploited for retinal studies.
利用抗血清在光学显微镜水平的免疫细胞化学定位，确定了斑马鱼视网膜中谷氨酸、γ-氨基丁酸（GABA）和甘氨酸的分布模式。使用针对GABA合成酶谷氨酸脱羧酶的两种同工型（GAD65和GAD67）的抗体，进一步表征了观察到的GABA免疫反应性（GABA-IR）模式。在所有视网膜层均观察到谷氨酸-IR，其中光感受器、双极细胞和神经节细胞标记明显。双极细胞显示出最强的谷氨酸-IR，双极细胞轴突终末在整个内网状层（IPL）中清晰地呈现为分层排列的小点。这些发现表明存在多种假定的OFF和ON双极细胞亚型，包括一些以单个大（9微米×6微米）轴突终末为特征的ON双极细胞。GABA-、GAD-和甘氨酸-IR在内视网膜中最为强烈。总体而言，观察到的GABA、GAD65和GAD67的标记模式相似。在一群无长突细胞、神经节细胞层中的少数细胞、整个IPL以及水平细胞中观察到GABA-和GAD-IR。在IPL中，GABA-和GAD-IR结构均组织成两条宽带。在无长突细胞、网间细胞以及两个网状层中观察到甘氨酸-IR。在整个IPL中均鉴定出甘氨酸阳性终末，在第3亚层有一条明显的带，对应于在GAD和GABA染色切片中观察到的免疫阴性区域。我们的结果显示了斑马鱼视网膜中使用谷氨酸、GABA或甘氨酸作为神经递质的神经元的分布。在内视网膜中观察到的神经递质分布与先前对其他脊椎动物的研究一致，并表明斑马鱼在发育研究中的优势可用于视网膜研究。
