Pituitary and adrenal control of pancreatic endocrine function in the duck. III. Effects of glucose, oleic acid, arginine, insulin and glucagon infusions in hypophysectomized or normal ducks.

The existence of plasma metabolites (glucose, free fatty acids [FFA[, aminoacids [AA])--pancreatic hormones (insulin, glucagon) feedback mechanisms and of insulin-glucagon relationships were studied in hypophysectomised ducks; the insulinogenic effect of glucagon was also studied in normal ducks in physiological conditions. Glucose infusion stimulated insulin secretion in hypophysectomised ducks; during oleic acid infusion, plasma IRI (immunoreactive insulin) was not modified whereas plasma GLI (glucagon like immunoreactivity) level drops slightly. Arginine induced insulin and glucagon secretion. Plasma GLI did not decrease during insulin infusion. In normal ducks glucagon was insulinogenic, hyperglycaemic and hypoaminoacidaemic. These biological properties of glucagon were lost in hypophysectomised ducks, except the effect on plasma aminoacids. It is concluded that the anterior pituitary and the adrenal cortex indirectly control the endocrine function of the pancreas, via the plasma metabolites and the insulin-glucagon interactions. In normal ducks, glucagon is probably insulinogenic in physiological conditions.