周围神经再生时乙酰胆碱受体免疫电镜与肌功能观察

Effect of neuromuscular junctional acetylcholine receptor on muscular function in peripheral nerve regeneration

目的 了解周围神经再生时N-乙酰胆碱受体(N-AchR)改变与肌功能恢复关系。 方法 选用家犬测定喉返神经再生时肌功能及肌电位,采用透射免疫电镜结合图像分析技术观察神经肌肉接头(NMJ)及其N-AchR分布和含量改变。 结果 术后3周,突触前膜结构基本消失而后膜结构尚完整,N-AchR含量较健侧增多;术后6周,再生神经长入NMJ,并可记录到肌电位,但N-AchR含量处于最低状态,肌收缩微弱;术后12周,N-AchR增加,肌电位增强,出现轻度肌收缩;18周后神经末梢突触后膜接触良好,N-AchR明显增多并趋稳定,观察到明显的肌肉收缩。 结论 提示周围神经再生时N-AchR恢复程度决定着肌功能的恢复。

Objective In order to determine effect of neuromuscular junctional acetylcholine N receptor (N AchR) on muscular function in peripheral nerve regeneration Methods α bungarotoxin horseradish peroxidase (α BT HRP) conjugate electron microscopic immunocytochemical methods and computer analysis in intensity of immunocytochemical reaction were applied to observe the distrubution and relative quantity of junctional N AchR Laryngeal spontaneous and evoked electromyography and contractile tension were performed Results The synaptic nerve terminals and presynaptic membrane were segmentally disrupted and almost disappeared completely and were replaced by Schwanns cells at 3 weeks after neurorrhaphy At weeks 6, some of the regenerating axons returned to the neuromuscular junctions and all the muscle fibbers were reinnervated at weeks 12 But the original postsynaptic membranes were only partially in contact with the regenerated nerve terminals These conditions persisted until 18 weeks after neurorrhaphy, when the appearance of remyelination was found in the vicinity of the neuromuscular junctions The N AchR reaction product in the postsynaptic membrane were increased greatly at 3 weeks after neurorrhaphy about 1 28 times more than normal. But it decreased greatly at 6 weeks which was only 0 47 times less than normal Furthermore, it remained low level until 12 weeks after neurorrhaphy, at this trine reactive product was 0 72 times of normal sides However, it increased obviously to 0 83 times of normal sides at 18 weeks and didnt changed after that time Regenerating motor unit potentials, evoked electromyograph and contractile tension could be recorded at 6 weeks after neurorrhaphy, but the amplitude of electrical activities and the strength of contraction were very low After that time, they increased gradually with the increase of N AchR until 18 weeks after neurorrhaphy Conclusion The new AchR determines the recovery of muscular electrical activities and contractile tension in peripheral nerve regeneration