Hindlimb weight bearing in mice with acute experimental joint inflammation. (A) Time course of the effects of URB597 (3.0 mg/kg) on inflamed hindlimb weight bearing (baseline (BL) values represent pre-inflammation induction). Over the course of 3 hr, URB597 significantly improved hindlimb weight bearing when compared to vehicle. P <0.0001; two-way ANOVA; n =12. (B) Hindlimb incapacitance 30 minutes after local administration of URB597 to acutely inflamed knees. The anti-nociceptive effect of URB597 (3.0 mg/kg) was blocked by the CB1 receptor antagonist AM251 (0.2 mg/kg), but not the CB2 receptor antagonist AM630 (0.2 mg/kg). When URB597 was administered to the contralateral knee, there was no observable effect on hindlimb weight bearing. Data are means ± SEM. *P <0.05, **P <0.01; one-way ANOVA with Bonferroni's post hoc test; n = 9 to 14. ANOVA, analysis of variance; SEM, standard error of the mean.