[Effects of botulinum toxin type A injection for pathological characteristic of calf in rats with spinal cord injure]

Objective: To explore the effect of BoTN-A on pathological characteristics of calf (GM) and motor function of ankle dorsiflexors in SCI model rats. Methods: Thirty-six SD male rats (weight 260-280 g) were randomly allocated into normal control group and 12w-control group, NS-injection group and BT-injection group in this study.NS/BT-injection groups were divided into two subgroups separately (2w-NS, 2w-BT, 8w-NS, 8w-BT). No injection was applied in normal control group or 12w-control group.Saline/BoTN-A was injected in right GM in NS/BT-injection group at two different time points(2w, 8w). GM and Sol on right side of rats would be forwarded for pathologicalexaminations, such as muscle weight, myosin heavy chain (MyHC) electrophoretic analysisat the 12th week. Results: Compared with the other three groups, the muscle weights of GM and Sol in the BT-injection group significantly decreased.MyHC type ratioof GM and Sol on the right side in the BT-injection group also significantlychanged.According to subgroup comparisons, MyHC type ratio of GM and Sol on the injectedside in the 2w-BT subgroup was significant different from that of the 8w-BT subgroup.MyHC type ratios of GM on the non-injected side in the BT injection group also changed more than normal control group.The change of MyHC type ratio of non-injected GM was significantly higher in the 2 week-BT subgroup than that in the 8-week subgroup. Conclusions: BoNT-A intervention resulted in pathological changes not only in the injected GM in SCI rats, but also in non-injected GM and non-injected Sol.The effects of earlier (2 weeks) BoTN-A intervention on pathologic characteristicsof GM and Sol were larger than that of later intervention.