Cholecystokinin and glucose-induced insulinaemia in dogs with and without pancreatic acinar atrophy.

Abstract

The entero-insular hormonal axis was studied in eleven conscious Beagle dogs, loaded with glucose orally and intravenously. In five of them, exocrine pancreatic atrophy was induced by pancreatic duct occlusion with prolamine, and documented by means of the p-amino-benzoic acid test. After oral glucose, the duct-occluded dogs displayed higher blood glucose (log area 4.12 +/- 0.07 versus 3.76 +/- 0.10; p less than 0.01), less plasma insulin (log area 3.56 +/- 0.08 versus 3.99 +/- 0.08; p less than 0.01) and less cholecystokinin-like immunoreactivity (log area 2.64 +/- 0.09 versus 3.10 +/- 0.14; p less than 0.01) than controls. In controls, the peripheral venous insulin concentrations were higher after oral than after isoglycaemic intravenous glucose, and this difference was no longer demonstrable in duct-occluded dogs. In the latter, gel permeation chromatography of pool plasma after oral glucose revealed a relative decrease of cholecystokinin-like immunoreactivity species, which eluted at the positions of sulphated cholecystokinin octapeptide, cholecystokinin-33 and cholecystokinin-39, and at a position intermediate between these two. Also in the duct-occluded animals, intravenous infusion of sulphated cholecystokinin octapeptide, in addition to oral glucose, resulted in an increase in plasma insulin (log area 3.83 +/- 0.10 versus 3.64 +/- 0.06; p less than 0.01) and an improvement in oral glucose tolerance. It is concluded that in the dog 1) the absence of pancreatic acinar tissue is associated with a loss of gastrointestinal factors mediating glucose-induced insulin secretion, and 2) reduction of circulating endogenous cholecystokinin species may account at least in part for this defect.