Figure 4.

Antihyperalgesic effects of gabapentin on mechanical hyperalgesia in CCI rats. At day 45 after CCI injury, the ipsilateral paw withdrawal threshold (A and B) to a noxious mechanical stimulus, and guarding duration (C) and frequency (D) to a noxious cold stimulus were measured before and 2 hours after gabapentin (100 mg/kg, p.o.) or vehicle (DiH₂O, 2 mL/kg, p.o.) administration. Chronic constriction injury induced significant mechanical hyperalgesia (A and B) and cold allodynia (C and D) for both measures (*P < 0.05 compared with presurgery [naive] baseline). Gabapentin significantly reversed CCI-induced mechanical hyperalgesia in the ipsilateral hindpaw compared with predose baseline (#P < 0.05) or vehicle control (^P < 0.05). The data were analyzed using the repeated-measure two-way ANOVA post hoc Tukey multiple comparison test (A, C, and D) or unpaired t test (B). N = 8/group. ANOVA, analysis of variance; BL, naive baseline (day -1); CCI, chronic constriction injury (D45 after surgery); p.o., orally.