Fig. 5

Dural IL-6 causes hyperalgesic priming to GTN in the absence of PAR2. A Facial withdrawal thresholds in PAR2KO mice following treatment with IL-6 (n = 4), WT controls (n = 4) following treatment of IL-6, and WT controls following treatment with vehicle and subthreshold GTN. Note that there are 12 days between the last time point of 48 h on the left and the baseline for GTN administration, indicated by the broken x-axis (see Fig. 1C). Application of IL-6 significantly decreased withdrawal thresholds in both WT (†) and PAR2KO (§) mice and enhanced hyperalgesic priming to GTN compared to WT mice treated with vehicle. B Grimace scores of PAR2KO mice and their WT controls following treatment with IL-6 and GTN. IL-6 significantly increased grimacing in WT and PAR2KO mice compared to WT mice treated with vehicle. There is no significant difference in grimacing between Par2KO and WT mice treated with IL-6. ^†,§p < 0.05, ^††,§§p < 0.01, ^{†††,§§§}p < 0.001, ^††††p < 0.0001. Data are represented as mean ± SEM