Neuropeptide Y (NPY) and vasoactive intestinal polypeptide (VIP), but not galanin, are autonomic cotransmitters in the porcine pancreas

Abstract

The neuropeptide galanin has been identified as a potential sympathetic cotransmitter in the canine pancreas. Immunoreactive galanin, also present in nerve fibers of the pig pancreas, was therefore measured in the effluent from isolated perfused pig pancreas with preserved sympathetic (splanchnic) or parasympathetic (vagal) innervation with radioimmunoassays directed against both the N-terminus and the C-terminus of galanin. Electrical vagus stimulation increased the pancreatic exocrine secretion, the secretion of insulin and glucagon, and the release of VIP, but did not influence galanin release. Splanchnic nerve stimulation increased perfusion pressure and glucagon secretion, inhibited insulin secretion, and increased the release of NPY, but galanin release was not affected. We conclude that the pancreatic galanin nerve fibers belong neither to the sympathetic nor to the parasympathetic divisions of the efferent nerve supply to the pig pancreas.