Fig. 1. Time-response curves for tactile allodynia induced by intrathecal injections of dynorphin A (1-13). Saline, 0.9%,(group S; closed circle, n = 8), 0.25 nmol of dynorphin (group D0.25; triangle, n = 7), 1 nmol of dynorphin (group D1; square, n = 9), or 2 nmol of dynorphin (group D2; open circle, n = 7) was intrathecally administered and paw withdrawal thresholds were assessed by using von Frey filaments. *  P < 0.05  versus control; †  P < 0.05  versus group S. Data are expressed as mean ± SEM.