Hpyerglycemic effect of a mixture of sea cucumber and cordyceps sinensis in streptozotocin-induced diabetic rat

Sea cucumber and cordyceps sinensis are used as both food and traditional medicines in Asia. This study was carried out in order to investigate the hpyerglycemic effect of a mixture of sea cucumber (Apostichopus japonicas) and cordyceps sinensis (Cordyceps militaris) (SCC) in diabetic rat and explore the mechanism underlining such an effect. The diabetic model rat was induced with intraperitoneal injection of streptozotocin (STZ). The diabetic model rats were randomly divided into control group (0.9% NaCl), low dose group (300 mg SCC center dot(kg body weight)(-1)) and high dose group (1200 mg SCC (kg body weight)(-1)). Sodium chloride and SCC were intragastrically administered once a day for 35 d. Changes in fasting serum glucose and serum insulin content, oral glucose tolerance and liver and muscle glycogen content were routinely evaluated. Pancreas tissue and beta-cells of islets were observed under both optical and transmission electronic microscope, respectively. The abundance of glucose metabolism-relating genes in gastrocnemius and epididymal adipose tissue was determined with either reverse transcription PCR (RT-PCR) or western blotting. Results showed that SCC significantly decreased fasting serum glucose content, improved glucose tolerance and increased serum insulin and glycogen content; repaired STZ-injured beta-cells of diabetic rat, and increased the expression of phosphatidylinositol 3 kinase (PI(3)K), protein kinase B (PKB) and glucose transporter 4 (Glut4) encoding protein in both gastrocnemius and adipose tissue, and Glut4 encoding gene in peripheral tissue. Our findings demonstrated that SCC exerted an anti-hyperglycemic effect by repairing beta-cells and promoting insulin-mediated signal transduction pathway in insulin-sensitive gastrocnemius and adipose tissue.