Inhibition by nociceptin of the light-evoked release of ACh from retinal cholinergic neurones

摘要

The retina possesses cholinergic amacrine cells which release acetylcholine (ACh) in response to flickering light. Using an eye-cup preparation in anaesthetized rabbits we found that when the retina was exposed to nociceptin, the light-evoked release of ACh was reduced in a concentration-dependent manner (IC_50 =100 nM), the maximum effect being 60/100 inhibition. Opioid receptors were not involved in the inhibitory effect of nociceptin because its action was not blocked by naloxone (1μM) and furthermore μ- opioids enhanced the light-evoked release of ACh.