Inhibition of Oxytocin Release by Morphine and Its Analogs

Abstract

Summary

Two synthetic morphine analogs, butorphanol and oxilorphan have been found to inhibit suckling induced oxytocin (OT) release in lactating mice. Morphine when tested in a similar experimental set-up produced even greater inhibition. Naloxone could effectively block inhibitions induced both by butorphanol and by morphine. When injected alone, naloxone did not produce any inhibition. These results indicate that (a) butorphanol, oxilorphan and morphine inhibit suckling induced OT release in mice, (b) the analgesic property of these compounds is responsible for the inhibition, and (c) inhibition produced by morphine and butorphanol is specific in nature since it could be reversed by naloxone.