Fig. 2

Effects of intrathecal and intracisternal histamine on thresholds to mechanical and thermal stimuli in rats. Histamine injected intrathecally once daily during days 0–7 PO at doses of 100 and 200 ng reversed heat hyperalgesia following PSL on day 7 PO but did not affect mechanical allodynia (a, b), while intracisternal histamine alleviated both mechanical and thermal hypersensitivity (c, d). *P < 0.05, **P < 0.01, and ***P < 0.001, compared with the vehicle-treated group. ^## P < 0.01, compared with the baseline. n = 7–9/group