Sopungsungi-won (SP) prevents the onset of hyperglycemia and hyperlipidemia in Zucker diabetic fatty rats

Abstract

Sopungsungi-won (SP) is a known formula for senile constipation and diabetes mellitus, based on traditional Korean medicine. The preventive effect of SP on the development of overt diabetes in Zucker diabetic fatty (ZDF) rats was evaluated. When administered orally through a diet for 8 weeks, diabetic conditions such as hyperglycemia, polydipsia and hypertriglyceridemia were all ameliorated in SP-treated rats. In parallel with the onset and progression of hyperglycernia in the ZDF control rats; there was a marked decline in plasma insulin concentrations from 26.1 muU/ml, at age 7 weeks, to 14.8 muU/ml at age 15 weeks. In the SP-treated rats, however, the plasma insulin concentrations did not decline, and SP at a dose of 5 g/kg significantly increased the insulin levels to 31.9 muU/ml. Early normalization of plasma insulin and a retained ability to subsequently increase plasma insulin were indicative of a pancreatic beta cell protective action by the SP formula. In addition,expressions of an insulin-responsive gene and corresponding protein, glucose transporter 4 (GLUT4), in skeletal muscle, were also determined in SP- and rosiglitazone-treated ZDF rats. mRNA and protein levels of GLUT4 in SP-treated rats were upregulated in a dose dependent manner. Furthermore, when ZDF rats were treated with 2 g/kg of the SP formula, the activity of glucose-6-phosphatase was decreased by 49%, whereas the activity of glucokinase was increased by 196%, compared to the ZDF control rats. Taken together, these data provide evidence that the SP formula markedly lowered the plasma glucose levels, probably through an effect not only on improvement of insulin action, but through a combined stimulation of glycolysis and an inhibition of gluconeogenesis in the liver, and also suggest the validity of SP's clinical use in the treatment of type 2 diabetes mellitus following further toxicological investigation.