Rutin ameliorates diabetic neuropathy by lowering plasma glucose and decreasing oxidative stress via Nrf2 signaling pathway in rats

Rutin exhibits antidiabetic, antioxidant and anti-inflammatory properties, which makes rutin an attractive candidate for diabetic complications. The present study was designed to investigate the potential effect of rutin on diabetic neuropathy. After induction of diabetic neuropathy, rutin (5 mg/kg, 25 mg/kg and 50 mg/kg) were daily given to the diabetic rats for 2 weeks. At the end of rutin administration, rutin produced a significant inhibition of mechanical hyperalgesia, thermal hyperalgesia and cold allodynia, as well as partial restoration of nerve conduction velocities in diabetic rats. Furthermore, rutin significantly increased Na+, K+-ATPase activities in sciatic nerves and decreased caspase-3 expression in dorsal root ganglions (DRG). In addition, rutin significantly decreased plasma glucose, attenuated oxidative stress and neuroinflammation. Further studies showed that rutin significantly increased hydrogen sulfide (H2S) level, up-regulated the expression of nuclear factor-E2-related factor-2 (Nrf2) and heme oxygenase-1 (HO-1) in DRG. The evidences suggest the beneficial effect of rutin on diabetic neuropathy. Additionally, insulin (2 IU) and BG-12 (15 mg/kg) were used to investigate the mechanisms underlying the beneficial effect of rutin on diabetic neuropathy. Insulin achieved lower plasma glucose and BG-12 achieved comparable Nrf2 expression than/to rutin (50 mg/kg), respectively. In contrast, the beneficial effect of insulin and BG-12 was inferior to that of rutin (50 mg/kg), suggesting that both lowered plasma glucose and Nrf2 signaling contribute to the beneficial effect of rutin on diabetic neuropathy. In conclusion, rutin produces significant protection in diabetic neuropathy, which makes it an attractive candidate for the treatment of diabetic neuropathy.