Antitussive effect of beta-endorphin is mediated by mu-opioid receptors, but not by kappa- or epsilon-opioid receptors.
The present study examined the opioid receptors involved in the antitussive effect of beta-endorphin in mice. beta-Endorphin injected i.c.v. depresses coughs dose dependently in doses from 0.1 to 1 microgram. Blockade of mu-opioid receptors by pretreatment with beta-funaltrexamine significantly reduced the antitussive potency of i.c.v. beta-endorphin. However, the antitussive effect of beta-endorphin was not antagonized by nor-binaltorphimine, a kappa-opioid receptor antagonist. Moreover, i.c.v. injection of beta-endorphin-(1-27), an epsilon-opioid receptor antagonist, did not affect the antitussive effect of beta-endorphin. The results indicate that the antitussive effect of beta-endorphin is mediated by activation of mu-opioid receptors, but not of kappa- or epsilon-opioid receptors.
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Hoshi University, Tokyo, Japan.
J
J
Kamei
Y
Y
Iwamoto
M
M
Misawa
H
H
Nagase
Y
Y
Kasuya
D000818:Animals; D000996:Antitussive Agents / Q000494:pharmacology*; D002211:Capsaicin / Q000037:antagonists & inhibitors / Q000633:toxicity; D003371:Cough / Q000139:chemically induced / Q000517:prevention & control*; D007276:Injections, Intraventricular; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D009292:Narcotic Antagonists / Q000494:pharmacology; D017473:Receptors, Opioid, kappa / Q000187:drug effects*; D017450:Receptors, Opioid, mu / Q000187:drug effects*; D017480:Receptors, sigma / Q000187:drug effects*; D001615:beta-Endorphin / Q000494:pharmacology*
D000996:Antitussive Agents; D009292:Narcotic Antagonists; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D017480:Receptors, sigma; D001615:beta-Endorphin; D002211:Capsaicin