The effects of glyburide and insulin on the decreased β-adrenergic responsiveness of the gastrointestinal tract in rats with non-insulin-dependent diabetes

Abstract

1. 1. Decreased β-adrenergic responses have been reported in gastro-intestinal tract of rats with diabetes mellitus. Effects of glyburide and insulin on the decreased β-adrenergic responsiveness of the gastro-intestinal tract due to non-insulin-dependent diabetes were investigated using duodenum, jejunum and ileum from rats which were injected with alloxan in their neonatal periods. 2. 2. Insulin treatment of non-insulin-dependent diabetic rats for 10 days corrected the decreased β-adrenergic responses of the isolated duodenum, jejunum and ileum confirming the previous results obtained from insulin-dependent diabetic rats. 3. 3. Glyburide treatment alone for 3 weeks also reversed the changes in the gastro-intestinal β-adrenergic responses of non-insulin-dependent diabetic rats. Combination of glyburide with insulin, however, did not cause an additive or supra-additive interaction in terms of β-adrenergic sensitivities of the diabetic tissues. 4. 4. The results obtained in the present study strongly suggested that non-insulin-dependent diabetes may cause a decrease in the number of gastro-intestinal β-adrenoceptors, while glyburide and insulin treatments correct the changes related to β-adrenoceptors. The effect of insulin on the β-adrenergic sensitivity of diabetic rat duodenum, jejunum and ileum may occur via a direct mechanism, whereas glyburide seems to be effective on the β-adrenergic responses through the increases in the insulin secretion and/or in the number of gastro-intestinal insulin receptors.