Vincristine is a toxic chemotherapeutic agent which often triggers neuropathic pain through inflammation. Morin isolated from figs (Ficus carica) exerts anti-inflammatory and neuroprotective activities. We investigated whether morin ameliorates vincristine-induced neuropathic pain and the underlying mechanism. Vincristine was injected i.p. for 10 days (day 1-5 and day 8-12). Morin was orally administered every other day from day 1 to 21. The pain behaviors were determined by measuring paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). The axons of sciatic nerves were stained with toluidine blue to study the histological abnormality. Function deficit of sciatic nerves was evaluated by sciatic functional index and the sciatic nerve conduction velocity. Neuronal excitability was assessed electrophysiologically and inflammatory mediators were detected using western blotting in dorsal root ganglia. The vincristine-induced reduction in PWT, PWL, and body weight gain was attenuated by morin. Morin restored the sciatic nerve deficits both histologically and functionally in vincristine-injected rats. The vincristine-induced neuronal hyperexcitability and increase in the expression of IL-6, NF-κB, and pNF-κB were abolished after morin administration. This study suggests that morin treatment suppressed vincristine-induced neuropathic pain by protecting the sciatic nerve and inhibiting inflammation through NF-κB pathway.
Keywords: Inflammation; Morin; NF-κB pathway; Neuropathic pain; Vincristine.