Fig. 4

Dural neutrophil elastase (NE) causes hyperalgesic priming to GTN. A Facial withdrawal thresholds in PAR2KO mice following treatment of NE (n = 4), WT controls following treatment of NE (n = 4), and WT controls following administration of vehicle (n = 5) 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 NE significantly decreased withdrawal thresholds in WT mice and enhanced hyperalgesic priming to GTN compared to WT mice treated with vehicle (†) and PAR2KO administered NE (*). B Grimace scores of PAR2KO mice and their WT controls. NE significantly increased grimacing in WT mice compared to WT mice treated with NE. *, ^†p < 0.05, **,^††p < 0.01, ^†††p < 0.001, ^††††p < 0.0001. Data are represented as mean ± SEM