大鼠周围神经可塑性的实验研究

EXPERIMENTAL STUDY ON PERIPHERAL NERVE PLASTICITY IN RATS

目的通过建立大鼠感觉神经束(前臂内侧皮神经)近端与运动神经束(肌皮神经)远端吻合的神经再生模型,观察在靶器官改变时感觉神经的结构与功能发生的可塑性变化。方法取健康成年SD大鼠30只,雌雄不限,体重200～250g,随机分成3组,每组10只。每组大鼠左上肢制备实验模型,右上肢为正常对照,不作任何处理。A组:于距前臂内侧皮神经起点5mm处切断该神经,将其近端与切断的肌皮神经远端行无张力端端吻合;B组:于距肌皮神经入肌点5mm处切断该神经,将其远端与切断的前臂内侧皮神经近端行无张力的端端吻合;C组:切断肌皮神经和前臂内侧皮神经后不予吻合,形成肱二头肌失神经支配模型。于术后观察各组大鼠的一般情况、屈肘功能、肱二头肌湿重、肌纤维横截面积、诱发电位的潜伏期和波幅,行吻合口近端的神经乙酰胆碱酯酶(acetylcholinesterase,AchE)染色观察。结果术后所有大鼠一般情况良好,切口无感染,均存活至24周。术后各组大鼠左侧肘关节主动屈曲功能丧失,24周时A、B组大鼠主动屈肘功能均有恢复。根据"泼水清理实验"评估,A组获4～5分肢体7例,B组5例,均较C组0例有明显恢复(P<0.05),A、B组间差异无统计学意义(P>0.05)。在肱二头肌湿重、肌纤维横截面积方面,A、B组明显优于C组(P<0.05),A组与B组差异无统计学意义(P>0.05)。A、B两组大鼠电生理均可测得肱二头肌的诱发电位,吻合口近端的前臂内侧皮神经在AchE染色后可见到轴突深染的有髓神经纤维(运动神经纤维),在屈肘功能的恢复情况、诱发电位的潜伏期和波幅、吻合口近端的运动神经纤维数量方面,两组差异均无统计学意义(P>0.05)。结论当靶器官改变时感觉神经的结构及功能均发生了适应性的重塑,这种重塑可能为修复周围神经损伤提供一种新方法。

Objective To observe the plastic changes of sensory nerve in terms of structure and function when target organ changed through making the rat model of nerve regeneration by anastomosing the proximal end of sensory nerve and the distal end of motor nerve. Methods Thirty adult SD rats （male or female）, weighing 200-250 g, were randomized into three groups （n= 10 per group）. The left upper limb of the each rat was used as the experimental side, while the right upper limb as the control side. In group A, the medial antebrachial cutaneous nerve was cut 5 mm away from its origin and its proximal end was anastomozed end-to-end to the distal end of musculocutaneous away from its nerve entry point and the proximal end of medial nerve. In group B, the musculocutaneous nerve was cut 5 mm antebrachial cutaneous nerve were anastomozed end-to-end to the distal end of musculocutaneous nerve. In group C, medial antebrachial cutaneous nerve and musculocutaneous nerve were cut, without further anastomosis. Twenty-four weeks after operation, the general condition and the motion of the elbow joint of rats, the wet weight and muscle fiber cross-section area of the biceps brachii as well as the latent period and the amplitude of the evoked potential were observed and the acetylcholinesterase （AchE） staining of nerve of proximal end of anastomosis was conducted. Results All the rats survived for 24 weeks with good general condition and without wound infection. The rats in groups A, B and C were lost the active flexion of left elbow joint after operation. The rats in groups A and B got recovered to some degree at 24 weeks. The behavioral evaluation showed that there were 7 limbs in group A and 5 limbs in group B scored as 4-5 points, there was a significant difference when compared with group C （P 〈 0.05）, but there was no significant difference between group A and group B （P 〉 0.05）. Group A and group B were superior to group C in terms of the wet weight and the muscle fiber cross-section area of the biceps brachii （P 〈 0.05）, but no significant difference between group A and group B was detected （P 〉 0.05）. The evoked potential of the biceps brachii and motor nerve fibers in proximal end of anastomosis could be detected in both group A and group B. But there was no significant difference between group A and group B with respects of fimction recovery of elbow joint, the latent period and the amplitude of the evoked potential of the biceps brachii and the quantity of motor nerve fiber in proximal end of anastomosis （P 〉 0.05）. Conclusion The change of target organ leads to the sensory nerve plasticity structurally and functionally, which may provide a new approach for peripheral nerve repair.