U0126 administration reversed the analgesic effect of acupuncture needling in the formalin-induced pain model. (A, B) Formalin-induced nociceptive behavior during the second phase. Ten minutes after the formalin injection, nociceptive behavior, such as flinching, licking, and biting the right hind paw, was recorded for 20 minutes, and the total time was analyzed (A). Nociceptive behavior for 5-minute blocks during the second phase (B). (C, D) Formalin-induced mechanical allodynia during the second phase. After formalin injection and acupuncture needling, Von Frey filaments exerting .6 g of force were applied a total of 10 times to the plantar surface of the right hind paw every 5 minutes. The frequency of positive responses was calculated and the total frequency was summated (C). The mechanical threshold for 5-minute blocks during the second phase (D). (*P < .05, **P < .01, ***P < .001, compared to the CON group; #P < .05, ##P < .01, ###P < .001, compared to the FOR group; §P < .05, § §P < .01, §§§P < .001, compared to the ACU group. One-way ANOVA was followed by the Newman-Keuls test [A,C] and 2-way ANOVA was followed by the Bonferroni test [B, D], each n = 8). Error bars indicate SEM.