Intracisternal rat pancreatic polypeptide stimulates gastric
emptying in the rat.
McTigue, Dana M., Chi-Hsiang Chen, Richard C. Rogers, and Robert L.
Stephens, Jr.
Department of Physiology, College of Medicine, Ohio State
University Columbus, OH 43210
APStracts 2:0047R, 1995.
Pancreatic polypeptide (PP) has been shown to alter gastrointestinal
functions, including increased gastric acid secretion and motility
following brainstem injections of PP. The present study investigated
the effect of an intracisternal (ic) injection of PP on the rate of
gastric emptying. Additionally, the efficacy of the rat and bovine
forms of the peptide was compared. Rats anesthetized with ether
received an ic injection of rat PP, bovine PP, or vehicle and, upon
regaining consciousness, were fed a liquid test "meal".
Intracisternal rat PP produced a marked enhancement in gastric
emptying compared to control animals. Bovine PP, at doses equimolar
to or three times greater than the effective rat PP dose, produced no
change in gastric emptying. Pretreatment with systemic atropine prior
to central injection of rat PP eliminated the stimulation of emptying
suggesting that PP acts through a cholinergic mechanism. When
equimolar doses of rat or bovine PP were microinjected directly into
the dorsal vagal complex, the region containing PP receptors, both
were capable of stimulating antral motility. The response to bovine
PP, however, was delayed and reduced compared to that seen following
rat PP. The results suggest that rat PP strongly stimulates gastric
emptying in rats and that bovine PP, depending the route of
administration, is either ineffectual or a weaker agonist for central
PP receptors.
Received 22 July 1994; accepted in final form 9 February 1995.
APS Manuscript Number R403-4.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 February 1995.