Decreased gastro-intestinal responses to certain agonists in streptozotocin- and alloxan-diabetic rats in vitro.

In this study, the beta-adrenergic, muscarinic and serotonergic receptor activities were investigated in alloxan- and streptozotocin-diabetic rats using duodenum, ileum and gastric fundus strips as assay organs. In addition, the effect of manganese chloride on the duodenum of normal and diabetic rats was studied to understand whether it affects the gastro-intestinal adenylate cyclase activity. The results obtained in this study suggest that no significant changes occur in the gastro-intestinal muscarinic receptor and adenylate cyclase activities due to experimental diabetes. Nevertheless, the experiments performed on the rat duodenum and gastric fundus strips with salbutamol and serotonin showed that the beta-adrenergic and serotonergic receptor activities of the gastro-intestinal tract decreased significantly in alloxan- and streptozotocin-induced diabetes. The results obtained seem to show that the gastro-intestinal complication(s) of the diabetes were related to the reduction(s) of the beta-adrenergic and/or serotonergic receptor activities.