大鼠脊髓横断伤后后肢运动功能恢复的规律

Recovery law of hind limb function following complete spinal cord transection injury in rats

目的 研究大鼠脊髓完全性损伤后后肢运动功能恢复的规律并探讨其机制。方法 1 5只SD大鼠于T9平面切断脊髓并切除 3mm使其完全横断。于伤后 1 ,2 ,4,6周行后肢运动功能联合评分 (CBS)及Basso -Beattle -Bresnahan (BBB)评分。并于伤后 6周行组织学、免疫组化、脊髓运动诱发电位 (MEP)检测及再次横断实验。结果 伤后后肢运动功能均有不同程度的恢复 ,4周时恢复速度最明显 ,6周时BBB最高评分可达 1 2分 ;MEP的结果与刺激电极的位置有关 ,刺激电极置于损伤平面以上时 ,不能引出MEP ,而置于损伤平面以下时 ,可引出正常波形的MEP ;损伤平面以上再次横断脊髓对已恢复的后肢运动功能无影响 ,而损伤平面以下再次横断则致再次完全截瘫 ;损伤处组织学检查为胶质瘢痕 ,未见轴索通过 ,有少量神经丝蛋白 2 0 0 (NF2 0 0 )阳性纤维 ,但零星、散乱。结论 大鼠脊髓完全性损伤后 ,后肢运动功能存在明显的自发性恢复 ,这种恢复与脊髓下行传导束的修复无关 ,而是损伤远段脊髓的自主功能。

Objective To observe the recovery process of hind limb function following complete spinal cord transection injury and discuss corresponding mechanism. Methods The spinal cords of 15 SD rats were transected at T9 plane and a 3 mm spinal cord removed for a complete transection. The functional recovery of the hind limb was evaluated using CBS (combined behavioral score) and Basso Beattle Bresnahan (BBB) 1, 2, 4 and 6 weeks after injury. At the 6th week after injury, also experiment was done on histology, immunohistochemistry, motor evoked potential (MEP) of spinal cord and repeated transection. Results The hind limb function of the injured animals recovered at different degrees, most obvious at the 4th week and BBB was up to 12 at the 6th week. MEP result was related to the site of the stimulating electrode. No MEP was recorded when the stimulating electrode was placed above the injured site. But when the stimulating electrode was placed below the injury level, MEP was normal. The again transection of the spinal cord above the injury level took no effect on the recovered hind limb. However, again transection below the injury level resulted in complete paralysis. Histologic results showed that the injured site was filled with glial scars without axons. There existed a little scattered positive fibers of neurofilament protein 200 (NF200). Conclusions After complete spinal cord injury, there is a significant spontaneous recovery of the hind limb function that is a kind of autonomous functions of the injured distal spinal cord unrelated to repair of descending conducting fasciculus of the spinal cord. The distal spinal cord is intact in function.