Fig. 1. Mechanical allodynia measured as the paw withdrawal frequency to stimulation with 2-g (  A ) and 12-g (  B ) von Frey filaments in Sprague-Dawley rats. Responses were measured after L5 spinal nerve transection (L5tx, n = 3), sham L5 spinal nerve transection (L5tx sham, n = 3), L5 nerve root ligation (LR, n = 3), or sham L5 nerve root ligation (LR sham, n = 3). Allodynia responses are reported as the number of paw withdrawals out of 30 possible responses ± group SEM. * Significant (  P < 0.01) difference in LR paw withdrawals compared with LR sham group. # Significant (  P < 0.01) difference in L5tx paw withdrawals compared with L5tx sham group. P.O. = postoperative.