Alleviative Effect of Ficus formosana Extract on Peripheral Neuropathy in Ovariectomized Diabetic Mice

In diabetes mellitus, Ficus formosana has been reported to ameliorate blood sugar levels and inhibit inflammation through its polyphenol and flavonoid contents. However, its effect on diabetic peripheral neuropathy (DPN) remains unknown. This study aimed to investigate the effect of Ficus formosana extract (FFE) on DPN in ovariectomized diabetic mice. Ovariectomized female C57BL/6J mice fed a high-fat diet plus streptozotocin injections to induce type 2 diabetes were orally administered FEE at 20 or 200 mg/kg BW daily, for 6 weeks. To evaluate the pain responses in the paws of the mice, a von Frey filament test and a thermal hyperalgesia test were performed. Additionally, the intraepidermal and sciatic nerve sections were examined, along with an assessment of inflammation- and pain response-related mRNA expression in the paws of the mice. The results showed that the oral administration of both 20 and 200 mg/kg BW FEE significantly alleviated the hypersensitivity of the paw and the abnormal proliferation and rupture of the C fiber, and reduced the mRNA expression of interleukin-1β, interleukin-6, interferon-γ, cyclooxygenase-2, and voltage-gated sodium channel 1.8 in the sciatic nerve of ovariectomized diabetic mice. We propose that FFE ameliorates peripheral neuropathy by suppressing oxidative damage in ovariectomized diabetic mice.