Effects of okadaic acid (OA, 2 μM) or ACSF infusion on the responses of dorsal horn neurons to mechanical stimuli following i.d. injection of capsaicin (arrows). OA (n = 6) or ACSF (n = 12) was continuously infused for 30 minutes before capsaicin injection (upper horizontal bars). The value before drug infusion was recorded as baseline. (A) Background activity; (B) Response to brush stimulus; (C) Response to press; (D) Response to pinch. ●○, P < 0.05, significant difference from baseline in each different lines. All values are presented as mean ± SEM.