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

In previous studies we found that duodenec-tomy abolished the interdigestive cycles of plasma motilin and pancreatic polypeptide (PP). In the current studies, we tested the hypothesis that an intact duodenopancre-atic axis is necessary for normal postprandial release of pancreatic (PP, insulin) and gut peptides (gastric inhibi-tory 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 concen-trations of PP and insulin were measured. Removal of the duodenum was associated with decreases in postprandialplasma 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 post-prandial plasma concentrations of GIP, CCK-8, neuroten-sin, 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 post-prandial insulin concentrations may be due to lack of a neural or humoral insulinotropic factor arising from the duodenum.