不同时间神经修复后失神经肌肉及运动终板变化的实验研究

目的 研究失神经支配肌肉不同时间神经修复后,肌肉及运动终板变化.探讨神经修复的最佳时机.方法 建立失神经支配腓肠肌实验模型,以损伤后不同的神经修复时间(0、2、4、6、8、10周)随机分为6组,每组6只.右后肢为实验侧,左后肢不作任何处理为对照侧(对照组).神经修复手术后第6周取材,测定各项检测指标.结果 肌肉失神经支配0～4周组行神经修复后肌肉湿重呈下降趋势,但各组间比较差异无统计学意义(P>0.05);4周后神经修复组肌肉湿重下降尤为明显,维持于一定水平,肌细胞直径及截面积呈持续性下降.2周内神经修复组,运动终板降钙素基因相关肽(calcitonin gene-related peptide,CGRP)灰度值与对照组比较差异无统计学意义(P>0.05);4,6周组,CGRP灰度值明显低于2周内神经修复组(P<0.05);8周后进行神经修复其灰度值进一步下降,与6周内神经修复组比较差异有统计学意义(P<0.05).超微结构的变化趋势与透射电镜观察基本一致.结论 实验提示神经损伤后2～4周内修复效果较好,6周后修复萎缩肌肉逆转可能性降低,但其各项指标仍能维持在一定水平,有指征尝试手术修复.

Changes of denervated skeletal muscle and motor endplate after nerve repair with different intervals of delay:an experimental study

Objective To investigate the changes of denervated skeletal muscle and motor endplate after nerve repair with various intervals of delay,and discuss the best timing for nerve repair. Methods Gastrocnemius muscle denervation was established in 36 SD rats which were randomly divided into 6 groups based on different intervals of delay for surgical nerve repair(0,2,4,6,8,10 weeks),with 6 each.All the manipulations were done on the right hind limbs while the unoperated left hind limbs served as control.Six weeks after nerve repair,muscles were harvested for evaluation.Results When nerve repair was carried our within 0 to 4 weeks of denervation,muscle wet weight continued to drop but showed to significant statistical difference between the groups(P>0.05).Muscle weight showed a remarkable drop when nerve repair was done after a 4week delay,and then maintained at a certain level.Diameter and cross sectional area of muscle fibers continued to decline.When the injured nerve was repaired within 2 weeks,the CCRP(calcitonin gene-related peptide)gray scale of motor endplate was not significantly different from that of the control side(P>0.05).The gray scale of CGRP of motor endplate in groups when nerve repair was done after 4 to 6 weeks was significantly lower than that in the group when nerve repair was done within 2 weeks(P<0.05).In the group of nerve repair with 8-week delay,CGRP gray scale further-declined,being significantly different(P<0.05)compared to that of the 6 week repair group.Ultrastruetural changes were in agreement with light microscopic changes.Conchlusion Nerve repair done within 2 to 4 weeks of injury lead to better results.Although muscle atrophy was less likely to be reversible when nerve repair was delayed for 6 weeks,there were still indications for nerve repair since some parameters still remained at a certain level.