Effect of Gymnema sylvestre on Insulin Receptor (IR) and Proglucagon Gene Expression in Streptozotocin Induced Diabetic Rats

Aim: To study the expression of Insulin Receptor (IR) in pancreas and proglucagon in the ileum homogenate with the hydroalcoholic extract of Gymnema sylvestre (HAGS) in streptozotocin induced diabetic rats. Materials and Methods: The HAGS was administered once daily at 100, 200 and 400mg/kg bd.wt for 28 days to STZ induced diabetic rats. Blood samples were collected at the end of 28 days. Serum blood glucose, glycosylated hemoglobin (HbA1c), insulin levels; SOD (Superoxide Dismutase), CAT (Catalase), MDA (Malondialdehyde) were estimated in the pancreatic and liver homogenates and the expression of pancreatic Insulin Receptor (IR) and intestinal proglucagon were estimated at the end of 28 days treatment period in all the treatment groups. Results: The HAGS showed a significant reduction in the serum levels of glucose and HbA1c with elevated insulin levels in diabetic rats. The HAGS showed a significant reduction in MDA with elevated levels of SOD and CAT in the pancreatic and liver homogenates. The expression levels of pancreatic Insulin Receptor (IR) and intestinal proglucagon were increased significantly with HAGS in diabetic rats. Conclusion: It is concluded that HAGS has significant antihyperglycemic activity through stimulation of GLP-1 release and its enhanced proglucagon expression in ileum followed by Insulin Receptor (IR) expression in pancreas. This may be due to the presence of active principles like saponins, triterpenoids and anthraquinones in Gymnema sylvestre.