FIGURE 2.

Effect of pretreatment with opioid receptor antagonists on the anti-allodynia activity of curcumin in cancer-induced bone pain mice. Mice were treated with curcumin (120 mg/kg, i.p.) twice a day for 11 days after the injection of B16-F10 melanoma cells (1 × 10⁵, 5 μl). In the 11th day, The opioid antagonists naloxone (1 mg/kg, i.p.) (A), NTI (0.5 mg/kg, i.p.), β-FNA (0.5 mg/kg, i.p.), and nor-BNI (0.5 mg/kg, i.p.). (B) were administered at 10 min, 10 min, 4 h, and 30 min prior to curcumin (120 mg/kg, i.p.) injection, respectively. MPE% induced by curcumin (120 mg/kg, i.p.) 4 h after administration was evaluated. Data are shown as means ± SEM, n = 6 per group. *P < 0.05, **P < 0.01, and ***P < 0.001 compared with the vehicle + vehicle group, ^###P < 0.001 compared with the vehicle + curcumin group, one-way ANOVA followed by Bonferroni’s test.