Biological actions of peptide YY: effects on endocrine pancreas, pituitary-adrenal axis, and plasma catecholamine concentrations in the dog.

The present study was designed to gather information on the biological activity of peptide YY (PYY) in conscious dogs. PYY was infused intravenously at a dose of 238 pmol/kg X h, and plasma concentrations of glucose, insulin, pancreatic polypeptide (PP), ACTH, cortisol and catecholamines (norepinephrine-NE; epinephrine-E; dopamine-DA) were subsequently measured. PYY significantly increased plasma insulin levels transiently without effect on plasma glucose, but decreased plasma PP levels during all infusion periods. PYY stimulated both plasma ACTH and cortisol secretion, and this action of PYY was also shared by PP, with PP being less potent in ACTH-cortisol release. PYY further elicited specific changes in plasma catecholamine concentrations, i.e. an increase of NE but not of E, which were in contrast to the effects of insulin-induced hypoglycemia. PP failed to alter plasma insulin and catecholamine concentrations. These results suggest that PYY can affect anterior pituitary hormone secretion, sympathetic nervous outflow and pancreatic endocrine activity in addition to its known actions on gastric and pancreatic secretion in the dog.