Fig. 4

MCC22 does not induce pharmacologic tolerance. Arthritic K/B.g7 mice were treated daily with vehicle, MCC22 (0.008 μmol/kg/dose), or morphine (6.62 μmol/kg/dose). Mechanical pain thresholds were determined daily before (baseline) and after the administration of the indicated compound. The analgesic effect of MCC22 is apparent at days 1 and 3; in addition, the baseline pain tolerance increases in this group. In contrast, the analgesic efficacy of morphine is lost by day 3. Data are displayed as mean ± SEM; n = 4–10 mice/group. Data were analyzed using repeated measures two-way ANOVA with post-hoc Tukey’s test for multiple comparisons within treatment groups and Sidak’s test for multiple comparisons between treatment groups. *p < 0.05, **p < 0.01, ***p < 0.001