Watt C B, Su Y Y, Lam D M
Nature. 1984;311(5988):761-3. doi: 10.1038/311761a0.
In addition to conventional neurotransmitters such as acetylcholine, dopamine, glycine and gamma-aminobutyric acid (GABA), a number of peptide-immunoreactive substances have recently been localized in the vertebrate retina. The functional roles of these retinal peptides and their interactions with conventional neurotransmitters are largely unknown. We have previously shown that exogenous opiates affect both the release of GABA and the firing patterns of ganglion cells in the goldfish retina, and we have now begun a systematic characterization of the opioid pathways in the chicken retina, because, among vertebrate retinas, avian retinas contain the highest concentration of enkephalins. Monoclonal antibodies specific for enkephalin have been used to demonstrate that a subpopulation of enkephalin-containing amacrine cells exists in the chicken retina. This retina also synthesizes Met-enkephalin and releases it on cell depolarization. The enkephalin-induced inhibition of GABA release in goldfish retina led us to examine whether similar interactions occur in chicken, and if so, whether enkephalins and GABA coexist in the same amacrine cells. Our results, presented here, indicate that exogenous enkephalins do indeed inhibit GABA release in the chicken retina. Surprisingly, we found that although some amacrine cells contain both enkephalin and GABA, others contain only one or the other.
除了乙酰胆碱、多巴胺、甘氨酸和γ-氨基丁酸（GABA）等传统神经递质外，最近在脊椎动物视网膜中还发现了许多肽免疫反应性物质。这些视网膜肽的功能作用及其与传统神经递质的相互作用在很大程度上尚不清楚。我们之前已经表明，外源性阿片类物质会影响金鱼视网膜中GABA的释放以及神经节细胞的放电模式，现在我们已经开始对鸡视网膜中的阿片类途径进行系统表征，因为在脊椎动物视网膜中，鸟类视网膜中脑啡肽的浓度最高。针对脑啡肽的单克隆抗体已被用于证明鸡视网膜中存在含脑啡肽的无长突细胞亚群。该视网膜还能合成甲硫氨酸脑啡肽并在细胞去极化时释放它。脑啡肽对金鱼视网膜中GABA释放的抑制作用促使我们研究鸡视网膜中是否也存在类似的相互作用，如果存在，脑啡肽和GABA是否共存于同一无长突细胞中。我们在此展示的结果表明，外源性脑啡肽确实会抑制鸡视网膜中GABA的释放。令人惊讶的是，我们发现虽然一些无长突细胞同时含有脑啡肽和GABA，但其他细胞只含有其中一种。
