Myhr K L, McReynolds J S
Department of Physiology, University of Michigan, Ann Arbor 48109-0622, USA.
Vision Res. 1996 Dec;36(24):3933-8. doi: 10.1016/s0042-6989(96)00131-9.
The effects of cholinergic agonists and antagonists on electrical coupling between horizontal cells were studied in dark-adapted mudpuppy retinas. Carbachol and the nicotinic agonist 1,1-dimethyl-4-phenylpiperazinium (DMPP) uncoupled horizontal cells, but the muscarinic agonist oxotremorine did not. The uncoupling effects of carbachol and DMPP were blocked by the nicotinic antagonist D-tubocurarine and by the dopamine antagonist fluphenazine, indicating that carbachol uncoupled horizontal cells by stimulating dopamine release via nicotinic receptors. Carbachol also caused an increase in release of [3H]dopamine from retinas. D-Tubocurarine increased horizontal cell coupling, indicating that tonic cholinergic input was present in dark-adapted retinas. D-Tubocurarine did not reduce light-evoked uncoupling of horizontal cells, suggesting that cholinergic neurons are not an essential part of the direct pathway by which light causes an immediate increase in dopamine release.
在暗适应的泥螈视网膜中，研究了胆碱能激动剂和拮抗剂对水平细胞之间电耦合的影响。卡巴胆碱和烟碱激动剂1,1 - 二甲基 - 4 - 苯基哌嗪鎓（DMPP）使水平细胞解耦联，但毒蕈碱激动剂氧化震颤素没有。卡巴胆碱和DMPP的解耦联作用被烟碱拮抗剂筒箭毒碱和多巴胺拮抗剂氟奋乃静阻断，这表明卡巴胆碱通过烟碱受体刺激多巴胺释放，从而使水平细胞解耦联。卡巴胆碱还导致视网膜中[3H]多巴胺释放增加。筒箭毒碱增加了水平细胞的耦合，表明在暗适应的视网膜中存在紧张性胆碱能输入。筒箭毒碱并没有减少光诱发的水平细胞解耦联，这表明胆碱能神经元不是光导致多巴胺释放立即增加的直接途径的重要组成部分。
