THE DISTRIBUTION OF NPY-CONTAINING NERVES AND THE CATECHOLAMINE CONTENTS OF CANINE ENTERIC NERVE PLEXUSES

Our previous study demonstrated that PYY was a major neuropeptide in t he canine enteric nervous system, the present study defines the locati ons of NPY-containing enteric neurons. NPY-positive nerve cell bodies and fibers were numerous in gastric and pyloric myenteric plexuses as were positive nerve fibers in antral and pyloric muscle layers, pylori c sphincter muscle layers, and surrounding blood vessels. In contrast to findings for PYY, there were considerably fewer NPY-positive nerve cell bodies and fibers in the canine ileum and colon. Noradrenaline wa s the predominant catecholamine in all plexuses, the rank order of its contents being: deep muscular > submucous > myenteric plexus. The dop amine/noradrenaline ratio was constant in all plexuses; adrenaline was present in minor amounts. PYY is the more abundant neuropeptide in il eum and colon, and NPY has a greater presence in the gastric antrum, p ylorus, and surrounding blood vessels. PYY and NPY may play different functional roles in the GI tract. (C) 1997 Elsevier Science Inc.