Fig. 2.
PTH2R KO mice develop less thermal hypersensitivity and less tactile allodynia than WT in a chronic inflammatory injury model. Thermal and mechanical hindpaw withdrawal thresholds of PTH2R-KO and WT mice were evaluated over time following unilateral hindpaw injection of 20 μL of CFA. WT had thermal hypersensitivity on days 1–3 following injection (A; F9, 81 = 11.8; P < 0.001) but thermal sensitivity of PTH2R-KO mice was only significantly increased on day 1 (B; F9, 63 = 8.1; P < 0.001). Mechanical allodynia lasted for 20 d after CFA injection in WT (D; F9, 81 = 17.8; P < 0.001) but only for 10 d in PTH2R-KO (E; F9, 63 = 12.4; P < 0.001). Area under the curve measurements over the total experiment duration indicated significant differences between the thermal (C; P < 0.001, n = 8–10 per group) and mechanical (F; P < 0.001, n = 8–10 per group) sensitivities of WT and PTH2R-KO. Dotted lines indicate times over which withdrawal thresholds differed significantly from the presurgical value. P values in the legend refer to the effect of time. Symbols above the columns refer to the post hoc test. *P < 0.05, ***P < 0.001.