Nerve stretch injury induced pain pattern and changes in sensory ganglia in a clinically relevant model of limb-lengthening in rabbits.

摘要

We used a model of tibial lengthening in rabbits to study the udpostoperative pain pattern during limb-lengthening and udmorphological changes in the dorsal root ganglia (DRG), udincluding alteration of substance P (SP) expression. Four udgroups of animals (naive; OG: osteotomised only group; udSDG/FDG: slow/fast distraction groups, with 1 mm/3 mm udlengthening a day, respectively) were used. Signs of udincreasing postoperative pain were detected until the 10(th) udpostoperative day in OG/SDG/FDG, then they decreased in OG udbut remained higher in SDG/FDG until the distraction udfinished, suggesting that the pain response is based mainly udon surgical trauma until the 10(th) day, while the udlengthening extended its duration and increased its udintensity. The only morphological change observed in the DRGs udwas the presence of large vacuoles in some large neurons of udOG/SDG/FDG. Cell size analysis of the S1 DRGs showed no cell udloss in any of the three groups; a significant increase in udthe number of SP-positive large DRG cells in the OG; and a udsignificant decrease in the number of SP-immunoreactive small udDRG neurons in the SDG/FDG. Faster and larger distraction udresulted in more severe signs of pain sensation, and further udreduced the number of SP-positive small cells, compared to udslow distraction.