Interaction of opioid peptides and the dopaminergic system in the myenteric plexus of the guniea pig ileum

Abstract

The effects of treatment with dopamine agonists and 6-hydroxydopamine on the release of opioid peptides from the myenteric plexus of guinea-pig ileum were examined.Apomorphine or bromocriptine treatment at doses that act on dopamine autoreceptors to inhibit dopamine release resulted in a significant elevation of the release of opioid peptides.6-hydroxydopamine treatment, which produces a lesion of catecholaminergic nerve terminals also resulted in an increase in opioid peptide release.These findings indicate that interruption of dopaminergic transmission in the myenteric plexus produces an increase in the release of opioid peptides and suggest an inhibitory modulation of opioid peptidergic neurons by dopamine systems in the myenteric plexus of the guinea-pig ileum.