NEUROTRANSMITTERS IN THE VISUAL SYSTEM

脊椎动物视网膜为研究视网膜变性的机制提供了独特的优势。 中枢神经系统的信息处理 虽然 不同细胞类型的生理反应和突触连接 已经被广泛研究，大多数人使用的神经递质的身份 视网膜细胞未知。 在过去的几年里，我们研究了 在分离的、鉴定的视网膜细胞中合成候选递质 (Lam，1976）。 这些研究确立了使用分离的细胞用于 视网膜细胞的生理和化学特征，也表明 一些视网膜神经元可能不使用任何已知的候选者作为发射器。 基于这些发现，本研究提案的主要目标是 继续鉴定脊椎动物视网膜中的神经递质。 在 具体而言，有五个具体目标：（1）乙酰胆碱的合成， γ-氨基丁酸、儿茶酚胺和5-羟色胺 将使用Lam（1976）的方法研究细胞类型;（2）由于氨基酸 例如谷氨酸盐、天冬氨酸盐、牛磺酸和甘氨酸，也被认为 这些氨基酸的内源性水平，在确定的视网膜神经递质， 细胞将通过丹磺酰化和氨基酸分析来测量;（3）释放 将使用以下方法研究来自已识别视网膜细胞的候选发射器 光或高钾离子作为刺激;（4）从我们以前的研究，一些 细胞类型可能不使用任何已知的候选者作为发射器（Lam，1976）， 因此将从牛中提取和纯化诸如肽的物质 视网膜和这些物质的生理作用， 离体灌流兔视网膜电图和神经节细胞活动 视网膜将使用艾姆斯和花粉（1969）的方法进行测试;尝试将 也可以确定视网膜物质的结构， 对视网膜细胞的特异性和可逆性影响;这些研究可能建立 视网膜中新的递质的存在;（5） 在蝌蚪视网膜发育过程中， 检查并与电生理学和形态学研究相关 Nilsson and Crescitelli（1969）.

The vertebrate retina offers unique advantages for studying the mechanisms of information processing in the central nervous system. Although the physiological responses and synaptic connections of the different cell types have been extensively studied, identities of neurotransmitters used by most retinal cells are unknown. For the past few years, we have studied the synthesis of transmitter candidates in dissociated, identified retinal cells (Lam, 1976). Such studies establish the feasibility of using isolated cells for physiological and chemical characterizations of retinal cells, and also suggest that some retinal neurons may not use any known candidates as transmitters. Based on these findings, the main objective of this research proposal is to continue the identification of neurotransmitters in the vertebrate retina. In particular, there are five specific aims: (1) The synthesis of acetylcholine, gamma-aminobutyric acid, catecholamines and serotonin by each identified retinal cell type will be studied using the method of Lam (1976); (2) Since amino acids such as glutamate, aspartate, taurine and glycine have also been implicated as transmitters, the endogenous levels of these amino acids in identified retinal cells will be measured by dansylation and amino-acid analyses; (3) The release of transmitter candidates from identified retinal cells will be studied using light or high external K ion as stimuli; (4) From our previous studies, some cell types may not use any known candidates as transmitters (Lam, 1976), substances such as peptides will therefore be extracted and purified from bovine retinas and the physiological effects of these substances on the electroretinogram and ganglion cell activities of isolated perfused rabbit retinas will be tested using the method of Ames and Pollen (1969); attempts will be also made to determine the structures of retinal substances which have specific and reversible effects on retinal cells; these studies may establish the existence of new transmitters in the retina; (5) The appearance of transmitter syntheses during the development of the tadpole retina will be examined and correlated with the electrophysiological and morphological studies of Nilsson and Crescitelli (1969).