Effect of Chrysin on Mechanical Hyperalgesia in Chronic Constriction Injury-Induced Neuropathic Pain in Rat Model

OBJECTIVE: The present study aimed to assess the effect of Chrysin on mechanical hyperalgesia in chronic constriction injury (CCI)-induced neuropathic pain in Wistar rats. MATERIALS AND METHODS: Neuropathic pain was induced by CCI to the sciatic nerve in rats. Oral treatment of chrysin was given at doses of 50 mg/kg, 100 mg/kg, and 200 mg/kg in neuropathic rats. Mechanical hyperalgesia (in terms of paw withdrawal threshold [PWT]) was measured using Randall–Selitto analgesy-meter, and percent PWT was determined. Statistical analysis was carried out using GraphPad Prism 5 tool. RESULTS: In mechanical hyperalgesia test, treatment with chrysin 200 mg/kg, naive PWT, predose PWT, 0.5 h, 1 h, 2 h, and 4 h postdose PWT were found to be 141 ± 8.94 g, 60 ± 7.91 g, 107 ± 9.08 g, 113 ± 5.70 g, 106.0 ± 7.42 g, and 97 ± 9.08 g, respectively. The peak effect was observed at 2 h posttreatment for 50 mg and 100 mg while the peak effect for 200 mg was reached at 1 h, and the same was maintained till 2 h posttreatment. Chrysin 200 mg dose has shown maximal percent reversal (74%) at 2 h posttreatment. The percent reversal PWT of 50 mg/kg, 100 mg/kg, and 200 mg/kg at 2 h were 68%, 67%, and 74%, respectively. Chrysin has exhibited dose-dependent efficacy in CCI-induced neuropathic pain. In mechanical allodynia test, In chrysin (200 mg/kg) treatment group, naive PWT, predose PWT, 0.5 h, 1 h, 2 h, and 4 h postdose PWT were found to be 60.0 ± 0.0 g, 5.0 ± 1.10 g, 22.45 ± 6.62 g, 52.64 ± 18.29 g, 37.33 ± 17.56 g, and 29.83 ± 9.22 g, respectively. The percent reversal PWT of 50 mg/kg, 100 mg/kg, and 200 mg/kg at 2 h were 43%, 68%, and 87%, respectively. CONCLUSION: Chrysin attenuates neuropathic pain by ameliorating mechanical hyperalgesia and allodynia. Further studies are warranted to establish the mechanism.