Dispersed rat pancreatic acini were used to determine the effect of ga
lanin on the exocrine pancreas and on basal and secretagogue-stimulate
d amylase secretion. Basal amylase secretion and amylase release stimu
lated by cholecystokinin octapeptide, bombesin, 12-o-tetradecanoyl-pho
rbol-13-acetate (TPA), secretin, and vasoactive intestinal peptide wer
e not affected by galanin in doses ranging from 10(-12) to 10(-6) M. G
alanin, however, significantly inhibited the amylase release stimulate
d by sub- and supramaximal doses of carbachol. A time course study sho
wed that the inhibition by galanin occurred during the sustained phase
of carbachol-stimulated amylase secretion. The inhibitory action of g
alanin disappeared in acini obtained from animals pretreated with pert
ussis toxin (PTX). These results suggest that galanin inhibits carbach
ol-stimulated amylase secretion through a mechanism related to a PTX-s
ensitive G protein.