AIMTo study the role of oxidative stress in the initiation and development of diabetic neuropathy.

METHODSThe diabetic rats were induced with streptozotocin (STZ). The malondialdehyde (MDA) level, total superoxide dismutase (SOD) and Na(+) -K(+) -ATPase activity were measured in the sciatic nerves at various stages of diabetes. The correlation of the MDA level and Na(+) -K(+) -ATPase activity was analyzed in diabetic rats. The pathological changes of sciatic nerve at diabetic various stages were examined by light microscopy.

RESULTSThe MDA level increased significantly in diabetic sciatic nerves as compared to controls at all time intervals. Total SOD activity increased significantly in diabetic sciatic nerves as compared to controls at one month of diabetes and progressively decreased at three/six months of diabetes. Na(+) -K(+) -ATPase activity progressively decreased at three/six months of diabetes. The correlation analysis indicated that the Na(+) -K(+) -ATPase activity was negative correlation with the MDA level in the diabetic rats. Histopathological study of the diabetic sciatic nerves showed that the pathological changes were observed at 3 months of diabetes, the changes were more serious as the diabetic duration was longer.

CONCLUSIONOxidative stress is found to occur during the early stages of STZ-induced diabetes (no neuropathy) and this state is maintained after initiation of neuropathy. The decreased Na(+) -K(+) -ATPase activity is associated with oxidative stress in the diabetic rats. Therefore, oxidative stress plays an important role in the initiation and development of diabetic neuropathy.