Effects of droperidol on the biosynthesis and release of endogenous opioid peptides in guinea-pig ileum.

Acute administration of droperidol 2 or 5 mg kg-1 induced an increase in the inhibitory response obtained by stimulation at 10 Hz of the myenteric plexus longitudinal muscle preparation of the guinea-pig ileum. The increase in the response induced by droperidol was markedly reduced by naloxone which suggests that it is mediated by endogenous opioid release. Cycloheximide treatment significantly reduced the increase of the inhibitory response induced by droperidol, indicating that the biosynthesis and the release of endogenous opioid are increased by droperidol.