Fig 9. Evoked pain responses at post-injury day 7 in young and middle aged rats before or after sham or CCI surgery.

Mechanical hyperalgesia (Top), measured as threshold pressure eliciting paw withdrawal; heat hyperalgesia (Middle), measured as latency time to hind paw withdrawal from a radiant heat source; cold allodynia (Bottom), measured as time of attendance to the affected paw. Results are presented as means +/- SD, n = 11 YS, YCCI, MCCI and n = 9 MS. Data were subjected to Two-Way ANOVA comparing day 7 to pre-injury baseline and differences due to age. * p< 0.0001 comparing day 7 to baseline; there were no significant differences related to age. Similar results were obtained on Day 3, and on Day 7 comparing ipsilateral to contralateral hind paw responses (S2 Fig).