去神经支配后运动终板区域超微结构及乙酰胆碱酯酶含量变化与面肌功能恢复:神经损伤不同程度及损伤后不同时间的差异

Changes of ultrastructure and acetylcholine esterase content in motor end plate after denervation and the functional rehabilitation of facial muscles:different degree of nerve injury and different time after injury

目的:探讨不同程度面神经去神经支配后眼轮匝肌(简称眼肌)和口轮匝肌(简称口肌)运动终板形态结构的变化,以及反映运动终板退变和再生情况的乙酰胆碱酯酶在运动终板区含量的变化与面肌功能恢复的关系。方法:实验于2004-04/12在中国医科大学实验动物部,基础医学院组织胚胎学教研室,第二电镜室进行。取白色瞬目反射正常豚鼠30只,随机分为压榨右侧面神经总干15s组10只,30s组10只,切断组10只,每组又依术后观察时间分为1周和1个月两个亚组,每个亚组5只。从30只豚鼠中随机选取5只豚鼠的左侧面神经作为对照组。通过乙酰胆碱酯酶染色进行组织化学分析及光镜和电镜下眼肌和口肌的运动终板形态观察。结果:参加实验豚鼠30只,均进入结果分析。①术后1周时乙酰胆碱酯酶活性灰度值:压榨15s组,压榨30s组和切断组与对照组基本一致[眼肌:68.13±6.68,65.75±7.75,67.56±4.86,66.41±5.89,P>0.05;口肌:67.41±4.85,66.25±6.03,65.86±5.91,64.52±5.12,P>0.05]。②术后1个月时乙酰胆碱酯酶活性灰度值:术后1个月时各组豚鼠口肌乙酰胆碱酯酶活性灰度值仍没有明显变化(64.21±7.23,68.41±7.86,67.58±5.75,64.52±5.12,P>0.05),而压榨30s组和切断组高于对照组(76.12±4.51,85.21±5.12,66.41±5.89,P<0.05)。③透射电镜下运动终板超微结构的变化:去神经支配后1周,突触后膜和神经末梢萎缩,初级和次级皱褶均变浅,眼肌与口肌运动终板结构相似。去神经支配后1个月,切断组口肌,初级和次级皱褶继续变浅;压榨15s和30s组,口肌初级突触间隙接近正常。去神经支配后1个月,压榨30s组和切断组眼肌初级和次级皱褶继续变浅,有些次级皱褶消失。结论:①不同程度神经损伤后1周和1个月时,口肌运动终板处的乙酰胆碱酯酶含量没有明显变化,提示去神经支配后运动终板处的乙酰胆碱酯酶含量保持一定时间的稳定。②不同程度神经损伤>1个月时,眼肌运动终板处的乙酰胆碱酯酶含量下降较明显,提示对去神经支配的敏感性与肌肉种属和肌纤维类型不同有关。

AIM:To study the morphological changes of motor end plate(MEP)of orbicularis oculi muscle(M. oculi) and orbicularis oscular muscle(M. oscular),and the relationship between the content changes of acetylcholine esterase(Ache) which reflects the degeneration and regeneration of MEP and the functional rehabilitation of facial muscles after denervation.METHODS:The experiment was conducted in the Laboratory of Department of Animal Experiment, the Laboratory of Department of Histoembryology and the Second Electron Microscope Center of China Medical University from April to December 2004.Thirty cavies with normal white blink reflex were selected and divided randomly into three groups:10 in 15 s group,10 in 30 s group and 10 in excision group. Each group was divided into two subgroups based on observation time (one week and one month) after operation with five cavies in each subsection. The leftsidedness facial nerves of five cavies were selected randomly from 30 cavies as controls.Histochemical analysis was made by AchE staining and the morphogeny of MEP in M.oculi and M.oscular was observed under light and electron microscope.RESULTS:Totally 30 cavies were involved in the result analysis.①One week after operation,the grey value of AchE activity in the 15 s group,the 30 s group and the excision group was coincident basically with that in the control group(68.13±6.68,65.75±7.75,67.56±4.86,66.41±5.89 in M.oscular,P >0.05;67.41±4.85,66.25±6.03,65.86±5.91,64.52±5.12 in M.oculi ,P >0.05). ②One month after operation,the grey value of AchE activity in M. oscular had no changes apparently in all the groups(64.21±7.23,68.41±7.86,67.58±5.75,64.52±5.12,P >0.05);however,the grey value of AchE activity in M. oculi in the 30 s group and the excision group was higher than that of the control group(76.12±4.51,85.21±5.12,66.41±5.89,P< 0.05).③The changes of ultrastructure of MEP under electron microscope:One week after denervation,posterior member of the synapse and motor nerve ending became atrophy,and primary crease and secondary crease became shallow,and MEP structure of M.oculi and M.ocular was similar.One month after denervation,M.oscular primary crease and secondary crease in the excision group became shallow.M.oscular primary synaptic cleft was near to normal in groups 15 s and 30 s.M.oculi primary crease and secondary crease became shallow continually in the 30 s group and excision group,and some of the secondary synaptic fold disappeared. CONCLUSION:①Significant difference of AchE content in MEP of M. oscular was found after denervation in different degree at one week and one month,indicating AchE content in MEP keep stable for a certain time after denervation.②Over one month after denervation in different degree,AchE content in MEP of M.oculi decreased obviously,indicating that the sensitivity of denervation is related to muscle species and muscle fiber type.