Effects of enalapril on diabetic neuropathy in rats

Background: Neuropathy is one of the important complications of diabetes. Deficiency of the nerve conduction velocity (NCV) that occurs in both human diabetic neuropathy and animal diabetes models is one of the indicators for diabetic neuropathy. In the present study, we examined the effect of enalapril, angiotensinconverting enzyme inhibitor on NCV, number of endoneurial capillaries and thickness of the capillary basement membrane in motor sciatic nerves of diabetic and non diabetic rats. Materials and Methods: Fifty male rats, 300-450gr body weight, randomly divided into five equal groups (control, sham, diabetic, prevention and treatment). Diabetes was induced by subcutaneous injection of alloxan (140mg/kg). Body weight and fast blood sugar were measured at the beginning of experiment and every endweek during the course of experiment. Animals in the sham and prevention groups received enalapril orally (5mg/kg/day) since the beginning of the experiment for five weeks. Treatment group received enalapril (5mg/kg/day) for four weeks after five weeks without treatment. NCV in motor sciatic nerve was measured at the end of the period. Then, the number of capillaries and thickness of basement membranes in the endoneurium of the motor sciatic nerve in all groups were examined. Findings: NCV was reduced by 45% in diabetic rats compared with the control group (p<0.001) after five weeks of diabetes. In prevention group, oral administration of enalapril for five weeks could prevent reduction in NCV in diabetic rats by 62% (p<0.05). Deficiency of the NCV is ameliorated by four weeks of enalapril treatment by 66% (p<0.05), in addition, the number of endoneurial capillaries in sciatic nerve increased by 67% (p<0.05). Administration of enalapril to non diabetic rats (sham group) had no effect on NCV and number of endoneurial capillaries in motor sciatic nerve. Conclusion: Enalapril can have an effective role in prevention and treatment of diabetic neuropathy.