Neal M, Cunningham J
Department of Pharmacology, UMDS, St Thomas' Hospital, London.
Br J Pharmacol. 1994 Dec;113(4):1085-7. doi: 10.1111/j.1476-5381.1994.tb17106.x.
The retina is an area of the central nervous system that possesses intrinsic cholinergic neurones which release acetylcholine (ACh) in response to stimulation with flickering light. Using an eye-cup preparation in anaesthetized rabbits we found that when the retina was exposed to the P2-purinoceptor antagonist, PPADS, the light-evoked release of ACh was strikingly increased (by over 40%). In contrast, ATP reduced the light-evoked release of ACh by 20%. The inhibitory effect of ATP was not due to its catabolism to adenosine because it was not affected by the A1-adenosine receptor antagonist, DPCPX, in combination with adenosine deaminase. The actions of both ATP and PPADS were completely blocked by strychnine. We conclude that during physiological stimulation of the retina with light, ATP is co-released with ACh and partially inhibits ACh release by activating (with ACh) an inhibitory glycinergic feedback loop.
视网膜是中枢神经系统的一个区域，其中含有内在胆碱能神经元，这些神经元在受到闪烁光刺激时会释放乙酰胆碱（ACh）。我们在麻醉的兔子身上使用眼杯制备法发现，当视网膜暴露于P2嘌呤受体拮抗剂PPADS时，光诱发的ACh释放显著增加（超过40%）。相比之下，ATP使光诱发的ACh释放减少了20%。ATP的抑制作用并非由于其分解为腺苷，因为它不受A1腺苷受体拮抗剂DPCPX与腺苷脱氨酶联合使用的影响。ATP和PPADS的作用都被士的宁完全阻断。我们得出结论，在视网膜受到光的生理刺激期间，ATP与ACh共同释放，并通过（与ACh一起）激活抑制性甘氨酸能反馈回路来部分抑制ACh释放。
