Marc R E, Liu W L, Scholz K, Muller J F
Sensory Sciences Center, University of Texas Graduate School of Biomedical Sciences, Houston.
J Neurosci. 1988 Sep;8(9):3427-50. doi: 10.1523/JNEUROSCI.08-09-03427.1988.
Autoradiography of goldfish retinas incubated in micromolar levels of 3H-serotonin displayed 3 kinds of labeled somas in the inner nuclear layer: S1 amacrine cells with heavy labeling, large somas, and a sparse distribution (approximately 93/mm2); S2 amacrine cells with moderate labeling, smaller somas, and a denser distribution (approximately 500/mm2); and a subset of bipolar cells with light labeling, small somas, and a very dense distribution (approximately 4000/mm2). Serotonin-like immunoreactivity was observed only in S1 amacrine cells and their synaptic terminals. Radiolabeled terminals in the inner plexiform layer formed 4 strata that were differentially assigned to the 3 cell types. S1 amacrine cells arborized in sublayers 1 and 5, received inputs from type a1 bipolar cells and amacrine cells, and made synapses on other amacrine cells, type a1 bipolar cells and unidentified processes. Thus, S1 amacrine cells seem to receive significant input from "off-center" pathways. S2 amacrine cells arborized in sublayer 3 and made synapses onto amacrine cells. Labeled bipolar cell terminals were exclusively located in sublayer 2 and were identified as type a2 mixed rod-cone bipolar cells. We conclude that the S1 amacrine cell is truly serotonergic and that radiolabeling of S2 amacrine cells and type a2 bipolar cells is due to cross-specificity for another carrier or processes unrelated to their neurochemical identities. These observations partially reconcile many previous observations on the types, numbers, and synaptologies of teleost retinal neurons identified by different markers for indoleaminergic transmission.
用微摩尔浓度的3H - 5 - 羟色胺孵育金鱼视网膜后进行放射自显影，在内核层显示出3种标记的胞体：S1无长突细胞标记强烈，胞体大，分布稀疏（约93个/mm²）；S2无长突细胞标记中等，胞体较小，分布较密集（约500个/mm²）；还有一部分双极细胞标记浅，胞体小，分布非常密集（约4000个/mm²）。5 - 羟色胺样免疫反应仅在S1无长突细胞及其突触终末中观察到。在内网状层的放射性标记终末形成4个亚层，分别对应3种细胞类型。S1无长突细胞在亚层1和5分支，接受a1型双极细胞和无长突细胞的输入，并与其他无长突细胞、a1型双极细胞和未识别的突起形成突触。因此，S1无长突细胞似乎从“离中心”通路接收大量输入。S2无长突细胞在亚层3分支，并与无长突细胞形成突触。标记的双极细胞终末仅位于亚层2，被鉴定为a2型混合视杆 - 视锥双极细胞。我们得出结论，S1无长突细胞是真正的5 - 羟色胺能细胞，而S2无长突细胞和a2型双极细胞的放射性标记是由于对另一种载体的交叉特异性或与其神经化学特性无关的过程。这些观察结果部分调和了以前许多关于通过不同吲哚胺能传递标记鉴定的硬骨鱼视网膜神经元的类型、数量和突触学的观察结果。
