Effects of neuropeptide Y on insulin and glucagon secretion in the pig.

Neuropeptide Y (NPY)-nerves occur in the pancreas. We therefore infused synthetic porcine NPY directly into the pancreatic artery in anaesthetized pigs to study its direct in vivo influence on pancreatic blood flow and on insulin and glucagon secretion. NPY was given both under basal, normoglycemic conditions, and during an ongoing intravenous infusion of glucose, which raised plasma glucose levels to 20 mM. NPY was infused at 0.5 (n = 2), 5 (n = 3), 35 (n = 7), or 175 (n = 5) pmol/min. We found that NPY at 5, 35, and 175 pmol/min inhibited glucagon secretion. Furthermore, at 35 and 175 pmol/min, NPY also reduced pancreatic blood flow. In contrast, only at 175 pmol/min, NPY inhibited basal and glucose-stimulated insulin secretion. We conclude that in the pig NPY might participate in the regulation of glucagon secretion (as an inhibitor) and of pancreatic blood flow (as a vasoconstrictor). In contrast, NPY does not seem to be involved in the regulation of insulin secretion.