LIPOIC ACID IMPROVES NERVE BLOOD-FLOW, REDUCES OXIDATIVE STRESS, AND IMPROVES DISTAL NERVE-CONDUCTION IN EXPERIMENTAL DIABETIC NEUROPATHY

OBJECTIVE - To determine whether lipoic acid (LA) will reduce oxidativ e stress in diabetic peripheral nerves and improve neuropathy. RESEARC H DESIGN AND METHODS - We used the model of streptozotocin-induced dia betic neuropathy (SDN) and evaluated the efficacy of LA supplementatio n in improving nerve blood flow (NBF), electrophysiology, and indexes of oxidative stress in peripheral nerves affected by SDN, at 1 month a fter onset of diabetes and in age-matched control rats. LA, in doses o f 20, 50, and 100 mg/kg, was administered intraperitoneally five times per week after onset of diabetes. RESULTS - NBF in SDN was reduced by 50%; LA did not affect the NBF of normal nerves but improved that of SDN in a dose-dependent manner. After 1 month of treatment, LA-supplem ented rats (100 mg/kg) exhibited normal NBF. The most sensitive and re liable indicator of oxidative stress was a reduction in reduced glutat hione, which was significantly reduced in streptozotocin-induced diabe tic and alpha-tocopherol-deficient nerves; it was improved in a dose-d ependent manner in LA-supplemented rats. The conduction velocity of th e digital nerve was reduced in SDN and was significantly improved by L A. CONCLUSIONS - These studies suggest that LA improves SDN, in signif icant part by reducing the effects of oxidative stress. The drug may h ave potential in the treatment of human diabetic neuropathy.