Figure 1

Trigeminal nerve injury, local infection and inflammation induced mechanical allodynia of the lower lip area. A). In rats having mental nerve (MN) ligation (n = 5), head escape threshold to von Frey stimulation decreased shortly after the injury (day 3) and remained low until the end of experiment (day 27). The decrease threshold observed in sham-operated rats (n = 3) shortly post-surgery disappeared completely after 10 days. B). Subcutaneous injection of LPS induced an acute mechanical hypersensitivity of the lower lip, which was significant at 5 hours post-injection (n = 5/group). C). CFA injection (n = 3 saline, n = 5 CFA) triggered mechanical allodynia during first three days post-injection and then progressively disappeared. ** P < 0.01, *** P < 0.001, compared to sham-operated group at their corresponding time point.