Time course of hyperalgesia after nerve injury in nude mice and heterozygous littermates. Nerve injury was carried out on day 0, after measurement of baseline thermal latencies. Thermal latencies and mechanical thresholds remained stable after sham operation in both types of mice (A). After injury to the sciatic nerve, thermal latencies in both the nude mice and their heterozygous littermates showed a reduction on the injured side. Heterozygous littermates showed significant thermal hyperalgesia for up to 84 days after nerve injury (B, open symbols). Thermal latencies also decreased in nude mice after nerve injury, but did not decrease to the same level as in their heterozygous littermates, and their recovery was faster (C, D). Mechanical thresholds remained stable after sham operation in both types of mice (E). Heterozygous littermates showed significant mechanical hyperalgesia after nerve injury up to POD 56 (F). Nude mice developed mechanical hyperalgesia, but recovered faster after the nerve injury (G, H). Error bars represent SD (n = 5). Data were analyzed by two-way repeated measures ANOVA followed by the post hoc Tukey test. Asterisks indicate a significant difference from the baseline value on day 0 (*P < 0.05, Tukey). Plus symbols indicate a significant difference between two groups, at indicated time-points (+P < 0.05, Tukey). BALB = Wild Type BALB/c mouse; POD = postoperative day.