Fig. 1

Effects of histidine on thresholds to mechanical and thermal stimuli in rats. Histidine (100 mg/kg, i.p.) administered once daily for three consecutive days did not affect hindpaw withdrawal thresholds to mechanical and thermal stimuli in naïve and sham-operated rats (a, b). Histidine treatment for 7 days (0–7 days PO) at various doses (25, 50, or 100 mg/kg, i.p.) alleviated mechanical allodynia (c) and thermal hyperalgesia (d) following PSL. **P < 0.01 and ***P < 0.001, compared with the vehicle-treated group. ^## P < 0.01, compared with the baseline. n = 7–9/group