Cholinergic independent dopaminergic regulation of motilin release in man.

This study investigated the dopaminergic control of motilin secretion in normal volunteers. Dopamine infusion caused a significant decline of plasma motilin levels, but had no effect on human pancreatic polypeptide (hpp) secretion. Dopamine antagonism with domperidone resulted in a significant elevation of motilin 10 and 20 min after the drug administration, and a significant elevation of hpp at 20 and 30 min. Atropine suppressed the basal levels of motilin and hpp but did not alter the increment of motilin levels after domperidone administration, while atropine suppressed domperidone induced secretory response of hpp. These results suggest that dopaminergic mechanisms exert a tonic inhibitory effect on motilin secretion in normal subjects.