Fig. 7

Tail flick latency (TFL) in rats treated with acupuncture needle with different roughness. Time zero denotes the onset of acupuncture treatment with rotation manipulation. Morphine was used as a positive control. NOR: non-treated normal group, Formalin + ACU: plain needle group, Formalin + ACU600: lightly scraped needle group, Formalin + ACU200: deeply scraped needle group, Formalin + MOR10: morphine group. ^*p < 0.05, ^**p < 0.01, ^***p < 0.001 versus NOR group; ^#p < 0.05, ^###p < 0.001 versus ACU group