Figure 3.

The effect of systemic Meteorin on cold allodynia induced by CCI in male SD rats. The response of the ipsilateral (left) hindpaw in 2 minutes to a noxious cold stimulus on a 4°C cold plate was assessed before and after CCI surgery at days 10, 12, 14, 17, 19, 21, 26, 32, 39, and 42. Meteorin (0.5, 1.8 mg/kg, s.c.) or vehicle (Dulbecco's PBS, 5 mL/kg, s.c.) was given at days 10, 12, 14, 17, and 19 after CCI. (A) Accumulated duration of guarding. (B) Bar graph illustrating the change of guarding duration at early and peak efficacy time points. (C) Guarding frequency. (D) Bar graph illustrating the change of guarding frequency at early and peak efficacy time points. Chronic constriction injury induced significant cold allodynia as assessed using both measures (*P < 0.05 compared with presurgery [naive] baseline). This effect diminished over time with repeated measurement. High-dose Meteorin (1.8 mg/kg) significantly reduced the guarding duration at days 12, 14, 17, 19, 21, 26, and 42 and guarding frequency at day 19 after CCI compared with predose baseline (#P < 0.05). The data were analyzed using the repeated-measure two-way ANOVA with the Tukey multiple comparison test (A) and the Friedman test with the Dunn multiple comparison test (B). N = 8/group. ANOVA, analysis of variance; CCI, chronic constriction injury; s.c., subcutaneously; SD, Sprague-Dawley.