COLOCALIZATION OF INHIBITORY MEDIATORS, NO, VIP AND GALANIN, IN CANINE ENTERIC NERVES

The colocalization of three putative inhibitory mediators of enteric n erves, vasoactive intestinal peptide (VIP), galanin (GAL) and nitric o xide synthase (nNOS), was examined in the myenteric plexus of canine a ntrum, intestine and colon. Many ileal and colonic neurons contained n NOS-immunoreactive (nNOS-IR) activity with some also containing VIP-IR ; only a few neurons also contained GAL-IR. Ileal and colonic VIP-IR n erves often appeared to be interneurons innervating nNOS nerves. Many antral neurons contained VIP-LR with nearly all also containing GAL-IR . A few also contained nNOS-IR. The predominance of nNOS-IR neurons re lative to VIP-TR and GAL-IR neurons in the ileal and colonic, but not the antral, myenteric plexus is consistent with NO being the primary i nhibitory mediator in the intestine but not in the antrum. (C) 1998 El sevier Science Inc.