Fig. 4

The mechanical allodynia in the upper back and thigh root occurred following 3 day FS in E2 treated rats with orofacial inflammation. a In the upper back, the mechanical allodynia persisted 7 days post FS in the E2 + CFA + FS rats (n = 8). *, ** p < 0.05, 0.01 vs baseline, respectively. In the oil + CFA + FS group, mechanical allodynia persisted till day 3 after FS (n = 7). ++ p < 0.01 vs baseline. No changes in the mechanical withdrawal threshold were found in the E2 + saline + FS group (n = 6), E2 + CFA + non-FS group (n = 6) and sham group (oil + saline + non-FS group, n = 7). b In the thigh root, the mechanical allodynia persisted 8 days after FS in the E2 + CFA + FS group (n = 8). *** p < 0.001 vs baseline. In the oil + CFA + FS group (n = 7), mechanical allodynia persisted till day 4 after FS. + p < 0.05 vs baseline. No changes in the mechanical withdrawal threshold were found in the E2 + saline + FS group (n = 6), E2 + CFA + non-FS group (n = 6) and sham group (oil + saline + non-FS group, n = 7)