Fig. 3

Repeated FS induced mechanical allodynia in the hindpaw of rats with orofacial inflammation. a In oil treated groups, only rats with CFA + FS (n = 10) exhibited mechanical allodynia lasting over 15 days post FS. **, *** p < 0.01, 0.001 vs baseline, respectively. The mechanical withdrawal threshold significantly decreased on day 11 post FS stress in the oil+CFA + FS rats compared with the sham treated rats. $ p < 0.05 vs the oil+saline+non-FS group at the same time point. There were not nociceptive changes in rats with FS alone (oil + saline + FS group, n = 9), CFA alone (oil + CFA + non-FS group, n = 8) or all sham treatment (oil + saline + non-FS group, n = 8). b In E2 treated groups, the mechanical withdrawal threshold significantly decreased for 15 days post FS stress in the E2 + CFA + FS group (n = 11). *** p < 0.001 vs baseline. FS alone produced mechanical allodynia on day 3 and day 7 after FS (E2 + saline + FS group, n = 8). ++, +++ p < 0.01, 0.001 vs baseline, respectively. CFA alone induced mechanical allodynia for 14 days after CFA injection (E2 + CFA + non-FS group, n = 8). #, ### p < 0.05, 0.001 vs baseline, respectively. The mechanical withdrawal threshold significantly decreased on day 3 to day 15 post FS stress in the E2 + CFA + FS rats compared with the sham treated rats. §, §§ p < 0.05, 0.01 vs the E2 + saline + non-FS group at the same time point, respectively. No mechanical allodynia was observed in the sham treatment group (E2 + saline + non-FS group, n = 8)