PACAP 1-38 as neurotransmitter in the porcine antrum

The concentration of PACAP 1-38 in porcine antrum amounted to 15.4 +/- 79 a nd 20.3 +/-8 pmol/g tissue in the mucosal and muscular layers. PACAP immuno reactive (IR) fibres innervated the muscular (co-localised with VIP) and su bmucosal/mucosal layers (some co-storing VIP and CGRP) including myenteric and submucosal plexus and blood vessels. Only myenteric nerve cell bodies c ontained PACAP-IR (co-storing VIP). In isolated perfused antrum, vagus nerv e stimulation (8 Hz) and capsaicin (10(-5) M) increased PACAP 1-38 release, PACAP 1-38 (10(-9) M) increased substance P (SP). gastrin releasing peptid e (GRP) and VIP release. PACAP 1-38 (10(-8) M) inhibited gastrin secretion and stimulated somatostatin secretion and motility dose-dependently. PACAP- induced motility was strongly inhibited by the antagonist PACAP 6-38 but al so by atropine and substance P-antagonists (CP99994/SR48968) but PACAP 6-38 had no effect on vagus-induced secretion or motility. Conclusion: PACAP 1- 38 may be involved in antral motility and secretion by interacting with cho linergic, SP-ergic. GRP-ergic and/or VIP-ergic neurones, and may also be in volved in afferent reflex pathways. (C) 2001 Elsevier Science B.V. All righ ts reserved.