Fig. 7. Spared nerve injury (SNI)–induced mechanical allodynia is both prevented and reversed by p38 inhibitor FR167653. (  A ) Prevention of mechanical allodynia. FR167653 (30 μg/μl, n = 5) was infused into intrathecal space  via an osmotic pump (0.5 μl/h for 5 days) starting 2 days before SNI. Note that the basal mechanical sensitivity does not change after FR167653. **  P < 0.01 , t test, compared with corresponding vehicle controls (30% dimethyl sulfoxide [DMSO], n = 8). (  B ) Reversal of mechanical allodynia. A bolus injection of FR167653 (20, 50, and 100 μg, 20 μl, n = 8 for each dose) into lumbar cerebral spinal fluid space, starting 3 days after SNI, reduces SNI-induced mechanical allodynia in a dose-dependent manner. The paw withdrawal thresholds were tested before the injection and at 1, 3, 6, and 24 h after the injection. *  P < 0.05, **  P < 0.01, compared with corresponding vehicle control (10% DMSO, n = 5).