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

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 m...

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Bibliographic Details
Published in:British journal of pharmacology 1997-04, Vol.120 (8), p.1399-1400
Main Authors: Neal, M. J., Cunningham, J. R., Paterson, S. J., Mcknight, A. T.
Format: Article
Language:English
Subjects:
Acetylcholine - metabolism
ACh release
Animals
Biological and medical sciences
cholinergic neurones
Eye and associated structures. Visual pathways and centers. Vision
Fundamental and applied biological sciences. Psychology
Light
Naloxone - pharmacology
Neurons - drug effects
Neurons - metabolism
Neurons - radiation effects
Nociceptin
Opioid Peptides - pharmacology
ORLI receptors
Rabbits
Receptors, Cholinergic - metabolism
Receptors, Opioid, mu - antagonists & inhibitors
retina
Retina - drug effects
Retina - metabolism
Retina - radiation effects
Special Reports
Vertebrates: nervous system and sense organs
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Summary: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 (IC50 = 100 nm), the maximum effect being 60% inhibition. Opioid receptors were not involved in the inhibitory effect of nociceptin because its action was not blocked by naloxone (1 μm) and furthermore μ‐opioids enhanced the light‐evoked release of ACh. Using rabbit retina homogenates we found that the retina possessed a substantial number of high‐affinity binding sites for [3H]‐nociceptin indicating the presence of ORLI‐receptors. Since [des‐Phe1]‐nociceptin, which has no affinity for the ORLI‐receptor, had no effect on the light‐evoked release of ACh it is unlikely that the action of nociceptin was simply non‐specific. We conclude that the inhibitory effect of nociceptin on retinal ACh release involves activation of the ORLI receptors. British Journal of Pharmacology (1997) 120, 1399–1400; doi:10.1038/sj.bjp.0701135
ISSN:0007-1188
1476-5381
DOI:10.1038/sj.bjp.0701135