Dopaminergic modulation of meal-stimulated and circadian secretion of pancreatic polypeptide in man.

This study investigated dopaminergic control of human pancreatic polypeptide (hPP) secretion in normal male volunteers. Dopamine infusion blunted the hPP response to a protein-rich meal. Dopamine antagonism with metoclopramide resulted in a hPP response at 5 min and a peak elevation of hPP 10 min after drug administration. Bromocriptine (2.5 mg, three times daily for 5 days) suppressed meal-induced secretory responses of hPP. Although bromocriptine did not alter the basic circadian pattern of hPP secretion, it did slightly increase nocturnal levels of this hormone. These results suggest that dopaminergic mechanisms exert a tonic inhibitory effect on hPP secretion in normal subjects.