AJP - Gastrointestinal and Liver Physiology, Vol 246, Issue 4 451-G456, Copyright © 1984 by American Physiological Society
Regulation of digestion. II. Effects of insulin and glucagon on pancreatic secretion
H. C. Tseng, J. H. Grendell and S. S. Rothman
The endocrine islet-cell hormones insulin and glucagon are secreted at high
concentrations into an intrapancreatic portal circulation and have been
reported to affect the secretion of digestive enzyme by the exocrine
pancreas. In the present experiments, insulin and glucagon were injected
into the celiac artery of anesthetized rats to evaluate their effects on
the secretion of amylase and trypsinogen by the pancreas. Neither hormone
when given alone significantly changed the output of either enzyme.
However, when given with the pancreatic secretagogue cholecystokinin, each
altered the effect of injection of cholecystokinin. In a dose-dependent
fashion insulin increased trypsinogen output without affecting amylase
output, whereas glucagon inhibited amylase output and left trypsinogen
output unchanged. Thus, both hormones produced a more trypsinogen-dominant
pancreatic juice than that observed with cholecystokinin alone, although in
different ways. These findings suggest that the endocrine hormones insulin
and glucagon may regulate secretion of digestive enzymes by the pancreas by
modulating the response to stimuli of overall protein secretion such as
cholecystokinin.
