Enhanced nocifensive responses to acetone application. (A) Acetone was applied to each separately hindpaw separately (5 trials per side) and results scored as % response. Higher percentage indicates development of cold hyper-reflexia. bCCI rats demonstrated significantly enhanced responsiveness (p < 0.001; F = 2442.5; df = 1; two-way ANOVA) for up to 43 days, which did not return to baseline. Each data point is group mean +/- SEM. (B) Acetone in a subgroup of 4 rats revealed that cold hyperalgesia persisted for up to 80 days.