beta-endorphin and Cough

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.

Topics: Animals; Antitussive Agents; beta-Endorphin; Capsaicin; Cough; Injections, Intraventricular; Male; Mice; Mice, Inbred ICR; Narcotic Antagonists; Receptors, Opioid, kappa; Receptors, Opioid, mu; Receptors, sigma