Role of the duodenum in postprandial release of pancreatic and gastrointestinal hormones.

In previous studies we found that duodenectomy abolished the interdigestive cycles of plasma motilin and pancreatic polypeptide (PP). In the current studies, we tested the hypothesis that an intact duodenopancreatic axis is necessary for normal postprandial release of pancreatic (PP, insulin) and gut peptides (gastric inhibitory peptide, GIP; cholecystokinin octapeptides, CCK-8; neurotensin; and gastrin). Consequently, we measured plasma concentration of pancreatic and gut hormones in normal and duodenectomized dogs after gavage feeding of a 250-ml liquid formula diet in conscious animals. After completing the experiments, pancreatic tissue concentrations of PP and insulin were measured. Removal of the duodenum was associated with decreases in postprandial plasma concentrations of PP (p < 0.05) and insulin (p < 0.05) and in pancreatic tissue concentrations of insulin (p = 0.01). Duodenectomy, however, did not alter postprandial plasma concentrations of GIP, CCK-8, neurotensin, or gastrin nor pancreatic tissue concentrations of PP. These effects of duodenectomy may be due to disruption of duodenopancreatic neural connections or loss of vagus sensitive (non-GIP) humoral factors. Decreased postprandial insulin concentrations may be due to lack of a neural or humoral insulinotropic factor arising from the duodenum.