Plasma cholecystokinin and pancreatic polypeptide secretion in response to bombesin, meal ingestion and modified sham feeding in lean and obese persons.

Disturbed satiety mechanisms may contribute to obesity. There has been speculation that cholecystokinin (CCK) and pancreatic polypeptide (PP) are involved in the regulation of satiety. We have therefore investigated whether there are differences between healthy lean and healthy non-diabetic obese volunteers in plasma CCK or PP release after a neuropeptidergic stimulation with bombesin and after infusion of a mixed meal. There were no differences in plasma CCK between groups either basally or in response to either form of stimulation. However, the plasma PP concentrations after the meal were significantly less in obese (2845 +/- 404 pM.min) than in lean subjects (5569 +/- 997 pM.min), whereas the plasma PP concentrations during bombesin were similar in both groups. We tested two other groups of nine obese and lean subjects to determine whether a disturbed vagal function could be the cause of the diminished plasma PP in obese persons, by studying the effect of modified sham feeding (MSF) on plasma PP. However, there were no significant differences in the plasma PP response to MSF between lean and obese subjects. We conclude that there are no differences between lean and obese persons in plasma CCK secretion in response to infusion of the neuropeptide bombesin or to ingestion of a mixed meal. However, the plasma PP after a mixed meal, is markedly diminished in obese subjects. This could not be attributed to a disturbed vagal cephalic stimulation.