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OPIOID RECEPTOR MODULATION OF NEURAL TRANSMISSION IN THE RABBIT COELIAC GANGLION AND GANGLIONIC OPIOID RECEPTOR ACTIVATION BY BUNITROLOL
Author(s) -
Horiuchi Jouji,
Terada Nobuyuki,
Takeuchi Tom
Publication year - 1989
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.1989.tb03003.x
Subject(s) - (+) naloxone , endocrinology , medicine , ganglion , trigeminal ganglion , opioid receptor , opioid , inhibitory postsynaptic potential , receptor , chemistry , anatomy , biology , neuroscience , sensory system
SUMMARY1 We examined the preganglionic splanchnic nerve activity and postganglionic renal nerve activity before and after a local injection of naloxone (20 ug/kg) into the coeliac ganglion of anaesthetized rabbits. This was done during graded hypertension, induced by the administration of phenylephrine (0.5‐10 ug/kg, i.v.) and with selective intraganglionic injection of methionine‐enkephalin (ME) and bunitrolol, which is a beta‐blocker. 2 During hypertension both pre‐and postganglionic discharge decreased, but only postganglionic discharge was inhibited by naloxone treatment into the ganglion. 3 Local injection of ME (0.1‐10 ug/kg) into the coeliac ganglion decreased postganglionic activity by 9.0 ± 1.0 to 41.2 ± 4.7% from control, and this decrease was inhibited by naloxone. 4 Administration of bunitrolol (1‐300 ug/kg) decreased postganglionic discharge by 3.9 ± 1.4 to 39.7 + 2.4% of the control and this decrease was also inhibited by naloxone. 5 These results suggest that opioid receptors in the coeliac ganglion play an inhibitory role in neural ganglionic transmission and that this inhibitory action reduces postganglionic sympathetic discharge.