Tributyltin exposure disturbs hepatic glucose metabolism in male mice

Some previous studies showed that organotin compounds induced diabetes in animal models. The underlying mechanisms should be further revealed. In this study, male KM mice were exposed to tributyltin (TBT) at 0.5, 5 and 50 mu g/kg once every three days for 45 days. The TBT-treated mice exhibited an elevation of fasting blood glucose level and glucose intolerance. The fasting serum insulin levels were increased and reached a significant difference in the 50 mu g/kg group; the glucagon levels were significantly decreased in all the treatments. Pancreatic beta-cell mass was significantly decreased in all the treatments; a-cell mass showed a significant decrease in the 5 and 50 mu g/kg groups. The transcription of pancreatic insulin gene (Ins2) showed an up-regulation and reached a significant difference in the 5 and 50 mu g/kg groups, which would be responsible for the increased serum insulin levels. The transcription of glucagon gene (Gcg) in the pancreas was significantly down-regulated in the 5 and 50 mu g/kg groups. The protein expression of hepatic glucagon receptor was down-regulated, while the expression of glucose-6-phosphatase and phosphoenolpyruvate carboxykinase was up-regulated accompanied by increased hepatic glycogen content. These results indicated that hepatic gluconeogenesis was enhanced during insulin resistance stage caused by TBT exposure, which would exert a potential risk inducing the development of diabetes mellitus.