Chronic oral Silybum Marianum aqueous extract attenuates streptozotocin-diabetic neuropathy

Abstract

Background: Oxidative stress is implicated as a final common pathway in the development of diabetic neuropathy and pharmacological interventions targeted at inhibiting free radical production have shown beneficial effects. Since Silybum Marianum (SM) is a plant rich in phenolics which their role against oxidative stress and inflammation have been shown in prior studies, we tried to determine the protective effect of  aqueous extract of SM in streptozotocin (STZ)-induced diabetic neuropathy in rats.

Methods: Male wistar rats (n =40) were randomly divided into 4 groups, i.e. Vehicle-treated control (VC), Extract-treated control (EC), Vehicle-treated diabetic (VD), and Extract-treated diabetic(ED) groups. Animals in VC, EC, VD and ED groups received sterile saline or saline plus SM extract (200mg/kg) orally for 8 weeks. Diabetes was induced by a single intraperitoneal injection of STZ (60 mg/kg).

Results: We found significant reduction in motor nerve conduction velocity, tail flick latency in hot immersion test and hyperalgesia in both phases of formalin test of diabetic rats compared to age matched non-diabetic rats. SM treatment significantly improved the nerve conduction velocity and nociception in diabetic rats. The changes in lipid peroxidation status and anti-oxidant enzyme (Superoxide dismutase) levels observed in diabetic rats were significantly restored by SM treatment.

Conclusion: This study provides experimental evidence for protective effect of SM extract on nerve function and oxidative stress in animal model of diabetic neuropathy.