AJP - Gastrointestinal and Liver Physiology, Vol 255, Issue 3 298-G303, Copyright © 1988 by American Physiological Society
CNS regulation of gastric and autonomic functions in dogs by gastrin-releasing peptide
H. J. Lenz
Department of Medicine, University of California, San Diego 92103.
The central nervous system effects of canine gastrin-releasing peptide
(GRP) were studied on gastric acid secretion, emptying, blood flow, and the
autonomic nervous system in conscious dogs. GRP injected into the third
cerebral ventricle significantly (P less than 0.01) increased plasma
epinephrine but not norepinephrine concentrations. GRP (0.1-1.0 nmol/kg)
significantly decreased gastric acid secretion stimulated by an 8% peptone
meal, delayed gastric emptying of the liquid peptone meal, and increased
left gastric artery flow. Ganglionic blockade, truncal vagotomy, or
adrenalectomy did not abolish the inhibitory effect of GRP on gastric acid
secretion. However, ganglionic blockade or vagotomy abolished the
GRP-induced inhibition of gastric emptying, and ganglionic blockade or
adrenalectomy abolished the GRP-induced increases in left gastric artery
flow and plasma epinephrine concentrations. An intravenous infusion of
epinephrine that produced similar plasma concentrations of epinephrine that
were observed after cerebroventricular injection of GRP mimicked the
increase in left gastric artery flow induced by GRP. It is concluded that
1) GRP acts within the central nervous system to activate the
sympathoadrenal axis, 2) GRP inhibits gastric emptying of a liquid meal by
a vagally dependent mechanism and enhances left gastric artery flow by the
release of epinephrine from the adrenal medulla, and 3) the pathway(s) that
mediate the GRP-induced inhibition of gastric acid in the dog remain
unknown.
