Protective effects of chronic administration of silymarin on blood glucose and lipids and oxidative stress in diabetic rats

Introduction: In diabetic patients, decreasing of oxidative stress level and serum glucose and lipids is clinically important. In this study, the effects of chronic administration of silymarin (S) on blood glucose and lipids and oxidative stress in diabetic rats were investigated. Materials and Methods: In this experimental study, male rats (n =40) were randomly divided into 4 groups, i.e. control, S-treated control, diabetic, and S-treated diabetic groups. The treatment groups (in diabetic group, before induction of diabetes by i.p. administration of streptozotocin) were received an initial dose (200 mg/kg) and then a daily dose (100mg/kg) for 8 weeks. Serum glucose, triglyceride, total cholesterol, LDL- and HDL- cholesterol levels and activities of superoxide desmolase (SOD) enzyme and malondialdehyde (MDA) levels were determined before the study and after 8 weeks. Results: After 8 weeks, serum glucose, total cholesterol, LDL cholesterol, and triglyceride levels were increased (P=0.03-0.0001) and HDL- cholesterol level was decreased (P=0.03) significantly in the diabetic group as compared with the control group. S treatment of diabetic rats caused a decrease in serum glucose, total cholesterol, LDL cholesterol, and triglyceride levels (P=0.01-0.0001) and an increase in HDL- cholesterol level ((P=0.03). On the other hands, serum SOD antioxidant activity was decreased and serum MDA levels increased in diabetic rats in compared to the control group. In S-treated diabetic rats, serum SOD activity was increased and serum MDA levels decreased. Conclusion: Treatment of diabetic rats with silymarin not only decreases the level of serum glucose but also has beneficial effect on serum lipids and oxidative stress level.