Mosinger J L, Yazulla S
Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794.
J Comp Neurol. 1985 Oct 22;240(4):396-406. doi: 10.1002/cne.902400407.
Rabbit retinas were double labeled to determine the degree of colocalization of glutamic-acid-decarboxylase-like immunoreactivity (GAD-like IR) and 3H-GABA uptake using light (LM) and electron microscopic (EM) autoradiography. Both GAD-like IR and 3H-GABA uptake were found in amacrine cell bodies in the inner nuclear layer (INL) as well as in cell bodies in the ganglion cell layer (GCL), and throughout the inner plexiform layer. GAD-like IR was found in 32% of the amacrine cells in the INL, 86% of which also showed 3H-GABA uptake; 3H-GABA uptake was observed in 38% of the amacrine cells. However, only 72% of these cells showed GAD-like IR. Labeled cells in the GCL were only 10-15% as common as similarly labeled cells in the INL. As in the INL, all GAD-positive cells in the GCL were double labeled, but only 53% of the cells taking up 3H-GABA were double labeled. We suggest that labeled cells in the GCL were ganglion cells rather than displaced amacrine cells. Cells, in both the INL and GCL, that showed 3H-GABA uptake but no GAD-like IR had a higher average grain density than double-labeled cells, indicating that uptake by these cells was specific. The relevance to GABAergic function of 3H-GABA uptake without an indication of GAD-like IR is yet to be determined. Statistical analysis at the EM level showed that one-third of the GAD-positive synaptic terminals of amacrine cells were double labeled after a 4-month exposure. Longer exposures at the EM level should reveal a higher percentage of GAD-positive terminals because at the LM level, one-half of the double-labeled cell bodies were "lightly" labeled with grains. The high degree of colocalization of GAD-like IR and 3H-GABA uptake suggests that both markers may be useful for labeling GABAergic neurons in the rabbit retina.
对兔视网膜进行双重标记，以利用光学显微镜（LM）和电子显微镜（EM）放射自显影术确定谷氨酸脱羧酶样免疫反应性（GAD样IR）与³H-GABA摄取的共定位程度。在内核层（INL）的无长突细胞体、神经节细胞层（GCL）的细胞体以及整个内网状层中均发现了GAD样IR和³H-GABA摄取。在内核层中，32%的无长突细胞存在GAD样IR，其中86%的细胞也显示有³H-GABA摄取；³H-GABA摄取见于38%的无长突细胞。然而，这些细胞中只有72%显示有GAD样IR。神经节细胞层中的标记细胞数量仅为内核层中类似标记细胞的10 - 15%。与内核层一样，神经节细胞层中所有GAD阳性细胞均为双重标记，但摄取³H-GABA的细胞中只有53%为双重标记。我们认为神经节细胞层中的标记细胞是神经节细胞而非移位的无长突细胞。在内核层和神经节细胞层中，显示有³H-GABA摄取但无GAD样IR的细胞的平均颗粒密度高于双重标记细胞，表明这些细胞的摄取是特异性的。³H-GABA摄取而无GAD样IR迹象与GABA能功能的相关性尚待确定。电子显微镜水平的统计分析表明，在4个月的暴露后，无长突细胞的GAD阳性突触终末中有三分之一为双重标记。在电子显微镜水平进行更长时间的暴露应能揭示更高比例的GAD阳性终末，因为在光学显微镜水平，双重标记细胞体中有一半被颗粒“轻度”标记。GAD样IR和³H-GABA摄取的高度共定位表明这两种标记物可能都有助于标记兔视网膜中的GABA能神经元。
