AJP - Gastrointestinal and Liver Physiology, Vol 261, Issue 1 16-G21, Copyright © 1991 by American Physiological Society
Hormonal control of avian pancreas by gastrin-releasing peptide from the proventriculus
B. Campbell, A. Garner, R. Dimaline and G. J. Dockray
Physiological Laboratory, University of Liverpool, United Kingdom.
Endocrine cells in the acid-secreting part of the avian stomach, the
proventriculus, contain two forms of gastrin-releasing peptide (GRP) of 27
and 6 residues, respectively. We have examined the actions of exogenous
GRP-27 and GRP-6 and endogenously released GRP in the control of pancreatic
secretion in urethan-anesthetized turkeys. Chicken GRP-27 and the
structurally related amphibian peptide bombesin were potent stimulants of
fluid and protein output from the pancreas (at 6-100 pmol/kg, iv). GRP-6
had no significant effect at doses up to 1,000 times higher. A bombesin
antagonist, (CH3)2-CHCO-[D-Ala24]GRP-20--26-NHCH3, inhibited the action of
exogenous chicken GRP-27 but did not inhibit intravenous cholecystokinin
octapeptide (CCK-8). Distension of the proventriculus with a solution of
peptone produced an increase in the flow of pancreatic juice and an
increase in protein output, which was not reduced by atropine. The bombesin
antagonist produced a reversible inhibition of this response. A CCK-gastrin
antagonist, BOC-beta-Ala-Trp-Leu-Asp-O(CH2)2- phenyl(4F), which inhibited
the action of exogenous CCK, had no effect on the pancreatic response to
exogenous GRP-27 or to distension of the proventriculus with peptone. We
suggest that protein-rich solutions in the proventriculus release GRP,
which in turn acts directly on the pancreas to stimulate enzyme secretion.
