Fig. 2

Role of TRPA1 in pain behaviour of CFA-induced mono-arthritic mice after cold exposure. a Primary mechanical hyperalgesia (measured using pressure application measurement) before and 2 weeks after mono-arthritis induction in mice maintained at RT or exposed to cold (10 °C) for 1 h prior to measurements. b Primary mechanical hyperalgesia before and 1 week after mono-arthritis induction in mice maintained at RT. Primary mechanical hyperalgesia in (c) CD1 mice pretreated with vehicle or HC-030031 and (d) WT and TRPA1 KO mice 2 weeks after CFA injection and following 1 h cold exposure, n = 6–8, ^* p < 0.05, ^** p < 0.01 compared to baseline, using repeated measures two-way ANOVA and Bonferroni’s multiple comparisons. Weight bearing in (e) mice pretreated with vehicle or HC-030031 and (f) WT and TRPA1 KO mice 2 weeks after CFA injection and following 1 h cold exposure, n = 6–13, ^* p < 0.05 compared to baseline, ^# p < 0.05 compared to WT, using one-way ANOVA and Bonferroni’s multiple comparisons. CFA complete Freund’s adjuvant, KO knockout, RT room temperature, TRPA1 transient receptor potential ankyrin 1, WT wild-type