Effect of bofutsushosan on insulin resistance in Otsuka Long-Evans Tokushima Fatty (OLETF) rats

Obesity is a key factor in the development of the metabolic syndrome and is the most important risk factor for the development of insulin resistance. Previous studies have shown that bofutsushosan (BOF), a Kampo medicine has an anti-obesity effect. However, it remains unclear whether BOF could ameliorate insulin resistance. In the current study, Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of obesity-induced type 2 diabetes mellitus, were used to test the usefulness of BOF. Male OLETF rats and their lean counterparts Long-Evans Tokushima Otsuka (LETO) rats aged 13 weeks were randomly divided into four groups: LETO + saline, LETO + BOF, OLETF + saline, and OLETF + BOF. Saline and BOF were orally administered for 4 weeks. The euglycemic hyperinsulinemic clamp was performed and the glucose infusion rate (GIR) was used to evaluate insulin resistance in the rats. BOF treatment to OLETF rats resulted in less body weight increase and attenuated GIR decrease. These results suggested that, probably by improving insulin-dependent glucose uptake in skeletal muscle, BOF may control the advance of diabetes in this rat model of obesity-induced type 2 diabetes mellitus.