Rutin attenuates cuprizone-induced demyelination in C57BL/6 mice through activation of Nrf2 signaling and inhibition of NF-κB.

Objectives: Multiple sclerosis (MS) is a debilitating demyelinating disease characterized by oxidative stress and neuroinflammation. This study investigated the therapeutic potential of rutin, a natural flavonoid, in a cuprizone (CPZ)-induced mouse model of demyelination. Materials and Methods: Male C57BL/6 mice were fed a 0.2% CPZ diet for six weeks to induce central nervous system demyelination and were concurrently treated with rutin (50 or 100 mg/kg, intraperitoneally, for the last 14 days). Behavioral assessments, histochemical examinations, and immunohistochemistry for Nrf2, HO-1, NQO-1, and NF-kB p65 were then performed. Results: Behavioral tests revealed that rutin dose-dependently improved CPZ-induced motor coordination deficits in the pole, rotarod, and open-field tests. Histological analysis (LFB and H&E staining) demonstrated that rutin significantly attenuated demyelination in the corpus callosum. Mechanistically, immunohistochemistry showed that rutin treatment effectively up-regulated the key antioxidant pathway by increasing the expression of phosphorylated Nrf2 (p-Nrf2) and its downstream targets (HO-1 and NQO-1), while simultaneously suppressing the pro-inflammatory NF-κB p65 pathway. Conclusion: Our findings show that rutin protects against demyelination through a dual mechanism of enhancing endogenous anti-oxidant defenses and inhibiting neuroinflammation, highlighting it as a promising candidate for further studies on demyelinating disorders such as MS.