(A) Guarding pain behavior. The results are presented as mean and standard error of the mean (SEM) for eight rats in each group. Two-way ANOVA with repeated measures on one factor (interaction factor: F24, 210 = 1.64, P = 0.0360) followed by Bonferroni’s post hoc test for comparing the mean cumulative pain score at each time point among groups. (B) Withdrawal threshold to punctate stimuli applied to the hind paw. The results are presented as median with range for six rats in each group. Non-parametric Friedman’s test (Fr = 17.02, P = 0.0019) followed by Kruskal-Wallis test with Dunn post hoc test for between-group comparisons at each time point. (C) Withdrawal latency to heat stimulation. The results are presented as mean and SEM. Two-way ANOVA with repeated measures on one factor (interaction factor: F24, 150 = 1.163, P = 0.2855) followed by Bonferroni’s post hoc test for comparing the mean withdrawal latency at each time point among groups. * P < 0.05, ** P < 0.01, † P < 0.001 compared with the vehicle group at each time point. POD = postoperative day.