PACAP- (1-38) as neurotransmitter in pig pancreas: receptor activation revealed by the antagonist PACAP- (6-38)
Tornøe, K.; Hannibal, J.; Fahrenkrug, J.; Holst, J.J.
American Journal of Physiology 273(2 Pt 1): G436-G446
1997
ISSN/ISBN: 0002-9513 PMID: 9277423 Document Number: 474709
The pituitary adenylyl cyclase-activating polypeptide PACAP-(1-38) has potent pancreatic secretory effects. We studied its immunohistochemical localization, release, and contribution to secretion induced by electrical vagus stimulation using isolated perfused porcine pancreas and the PACAP receptor antagonist PACAP-(6-38) (10-7 M). PACAP was found in nerve fibers throughout the pancreas but, in particular, encircling ganglionic vasoactive intestinal polypeptide (VIP)-positive nerve cell bodies and, mostly, colocalized with VIP. Vagus stimulation caused its release. PACAP-(1-38) (4 10-9 M) juice and insulin (but not glucagon) outputs to 8.3 ± 4.2 and 67 ± 14%, respectively. In conclusion, 1) pancreatic PACAP fibers seem to activate intrapancreatic VIPergic neurons, 2) PACAP-(6-38) antagonism documents the role of VIP/PACAP for neural regulation but cannot distinguish their relative importance, and 3) a PACAP receptor with low affinity for PACAP-(6-38), associated with glucagon cells, may exist. Reprinted by permission of the publisher.