Figure 2

(a) Reversal of tactile allodynia by p38 inhibition after spinal nerve ligation (SNL) on mice. The p38 inhibitor FR167653 was injected (i.p., 50 mg/kg, in 10% DMSO) at 10 days after SNL. The same injection was repeated daily for additional 4 days (indicated with small arrows). SNL-induced mechanical allodynia was tested at 1 h, 3 h, 6 h, and 1 d after the first injection, then daily for another 6 days. Mean ± SEM (n = 5). Note that p38 inhibitor is still effective in reversing neuropathic pain. Interestingly, the effect is maintained for 2 more days after the last injection. (b) Inhibition of SNL-induced IL-1β upregulation in the spinal cord by p38 inhibition. ELISA shows that intrathecal injection of the p38 inhibitor SB203580 (10 μg, twice a day for 3 days) reduces SNL-induced IL-1β increase in the L5 spinal cord (dorsal part) 3 days after SNL (L5). **, P < 0.01, compared to Sham; ⁺, P < 0.05, compared to SNL, ANOVA.