Insulin resistance and low sympathetic nerve activity in the Tsumura Suzuki obese diabetic mouse: a new model of spontaneous type 2 diabetes mellitus and obesity

Tsumura Suzuki obese diabetic (TSOD) mouse is a new model of type 2 diabetes mellitus and obesity. The TSOD mice had hypoadiponectinemia. To assess the glucose utilization and insulin sensitivity, we examined the effect of insulin (1U/kg) on peripheral tissue glucose uptake in vivo in the TSOD and Tsumura Suzuki nonobese mouse using 2-deoxy-d-[3H]glucose. The rates constant of glucose uptake in basal condition without insulin were similar in the peripheral tissues in both strains. Insulin-stimulated glucose uptake by skeletal muscles and adipose tissues in vivo was diminished in the TSOD mice. In addition, we assessed norepinephrine turnover in brown adipose tissue and adrenal epinephrine (E) content and E turnover because disturbances in the sympathetic activities relate to many features in obese and diabetic syndrome. In these mice, the rate of norepinephrine turnover was decreased, and adrenal E content was at most one half of the Tsumura Suzuki nonobese mice and E turnover had extremely low rates. The TSOD mice showed hypercorticosteronemia. These results suggest that TSOD mice have insulin resistance and both low sympathetic nervous activities and low adrenomedullary activity, and have high adrenocortical activity, which are significant features of the TSOD mouse.