高选择性神经损伤对大鼠腓肠肌结构的影响

Effects of highly selective radicotomy on the structure of rat gastrocnemius muscles

为了研究单纯运动神经或感觉神经损伤对大鼠腓肠肌显微形态学和超微结构的影响,选用成年SD大鼠54只,分别切断左侧L4～L6神经前、后根和坐骨神经,建立大鼠单纯性神经损伤模型。于第2、4、10周分别在透射电镜下观测各组大鼠腓肠肌肌细胞直径、截面积和超微结构的变化。结果显示:(1)随着时间点的延长,神经损伤各组肌细胞直径及截面积呈现进行性缩小,超微结构损伤呈现进行性加重;(2)同一时间点前根切断组比后根切断组肌细胞直径及截面积有更大萎缩,具有显著性差异(P<0.01),超微结构改变以前根切断组最为明显;(3)与对照组比较,同一时间点各组中坐骨神经切断组的大鼠腓肠肌肌细胞直径、截面积的变化最大,前根切断组居中,后根切断组的变化最滞后,超微结构变化与此相一致。上述结果提示,感觉神经与运动神经对于骨骼肌具有不同的营养作用,骨骼肌萎缩对运动神经损伤具有更高的敏感性。

To examine the effects of highly selective radicotomy on the micromorphology and ultrastructure of rat gastrocnemius muscle. The left L4 - L6 ventral root, dorsal root and sciatic nerve of SD rats were cut down respectively to establish the rat model with highly selective radicotomy. The diameter, cross-sectional area and ultrastructure of myecytes were observed with transmission electron microscope after denervation at 2, 4 and 10 weeks. The results showed that： （ 1 ） In all the groups with highly selective radicotomy, a progressively decrease in diameter and cross-sectional area of myecytes was observed, and the damaged uhrastmcture was progressively aggrvated with prolonged time; （2） Compared with the dorsal root transection group, a more significant decrease in diameter and cross-sectional area of myo- cytes was observed in the ventral root transection group at the same time after denervation（P 〈0.01 ）. We also observed a more serious damage of ultrastructure in the ventral root transection group compared with the dorsal root transection group ; （ 3 ） Compared with the control group, the most significant changes of diameter, ultrastrueture and cross-sectional area of myecytes were observed in the sciatic nerve transection group; the ventral root transaction group had a lower change; and the least changes were observed in the dorsal root transection group. The variety in damaged myecyte uhrastrueture of all the groups was accorded with above that. These results suggest that motor and sensory nerve have different trophic effect on skeletal muscles. Skeletal muscle atrophy is more sensitive to motor nerve injury.