Dissociation between the action of somatostatin on insulinotropic and glucagonotropic activities of rat duodenal mucosa

Abstract

The secretion of glucagon and insulin being both inhibited by somatostatin appears in some ways paradoxical, knowing the antagonistic physiological action of these two hormones. Since they are both regulated in part by duodenojejunal factors within the gastroenteropancreatic system, the purpose of the present study was to examine whether somatostatin would affect differently the factors stimulating glucagon and those stimulating insulin release in response to food administration. Previous studies 1 have shown that intragastric administration of glucose to rats increased the insulinotropic activity contained in the duodenal mucosa when measured by an in situ rat pancreas preparation. Similarly, intragastric administration of arginine increased the glucagonotropic activity of the duodenal mucosa when measured in a similar bioassay (unpublished data). In the present study, the effect of somatostatin on the activation in the duodenum of insulinotropic or glucagonotropic activity by glucose or arginine, respectively, was determined.