The effect of parenteral and enteral nutrition on portal and systemic immunoreactivities of gastrin, glucagon and vasoactive intestinal polypeptide (VIP).

To compare the effect of parenteral with enteral nutrition on gastroentero-pancreatic hormones, hypercaloric and hypocaloric nutrient preparations, commonly used clinically, were administered to rats either through cannulae in the jugular vein or gastrostomies. Control rats were fed orally ad libitum. Portal and aortic plasma was collected for radioimmunoassay with antibodies to C-terminal regions of gastrin and glucagon and to N-terminal-to-central regions of glucagon and VIP. Levels of all immunoreactivities were significantly lower in aortic than portal plasma. Apparent clearance of glucagon and gastrin by liver or lung both was enhanced by administration of the hypercaloric nutrient intravenously. Only intragastric hypercaloric nutrition maintained levels of VIP immunoreactivity close to those of control rats. Intragastric administration of either preparation appeared to maintain adequate levels of gastrin. Differences in the levels of glucagon immunoreactivities may be related to the stimulatory effects of metabolites in the lower gut and pancreas.