Diphenyl diselenide alleviates diabetic peripheral neuropathy in rats with streptozotocin-induced diabetes by modulating oxidative stress

Diabetic peripheral neuropathy (DPN) is one of the most common microvascular complications occurring in both type 1 and type 2 diabetes mellitus patients. Oxidative stress (OS) plays a key role in the pathogenesis of DPN; thus, antioxidant therapy is considered a promising strategy for treating DPN. Diphenyl diselenide (DPDs) is an organic selenium compound with antioxidant pharmacological activities. This study aimed to evaluate its preventive and therapeutic effects on DPN in rats with streptozotocin (STZ)-induced diabetes and explore the underlying mechanisms. In vitro, RSC96 cells were exposed to high glucose (100 mM) and then treated with different concentrations of DPDs (1, 10, 25 and 50 mu M). Notably, DPDs markedly suppressed high glucose induced cytotoxicity and oxidative stress in Schwann cells by decreasing reactive oxygen species (ROS) and malondialdehyde (MDA) levels. Furthermore, the DPDs treatment effectively activated Nrf(2) signaling and inhibited Keap1 expression. An in vivo DPN model was established in Sprague-Dawley (SD) rats injected with STZ (60 mg.kg(-1), ip) and orally administered either different doses of DPDs (5 and 15 mg. kg(-1).d(-1)) for 12 weeks or alpha lipoic acid (ALA, 100 mg kg(-1).d(-1)) as a positive control. The administration of DPDs significantly increased the motor nerve conduction velocity (MNCV), improved thermal and mechanical hyperalgesia and the sciatic nerve morphology, and ameliorated oxidative stress in the serum and the sciatic nerve of rats with DPN. Mechanistically, DPDs reduced the level of Keap1 and stimulated Nrf(2) signaling in the sciatic nerve. Taken together, the results of this study indicate that DPDs ameliorates experimental DPN as an antioxidant by activating the Nrf(2)/Keap1 signaling pathway. DPDs may represent a new alternative treatment for DPN.