Pachter B R, Eberstein A
Department of Rehabilitation Medicine, New York University Medical Center, New York 10016.
Exp Neurol. 1992 Jun;116(3):246-55. doi: 10.1016/0014-4886(92)90004-a.
The long-term effects of partial denervation on the muscle fiber cross-sectional area, degree of axonal sprouting, and end-plate morphology were examined 1, 3, 6, 9, and 12 months postsurgery in rat plantaris muscle. After 1 month of partial denervation, mean cross-sectional areas of type I and type II myofibers were significantly lower than that of sham-operated controls; fiber atrophy and hypertrophy was observed. After 3 months, we found no statistical difference in the mean cross-sectional fiber area between the two experimental groups. After 6 months, the fiber areas were now significantly larger than controls, possibly the result of compensatory work hypertrophy, due to the overuse of remaining hyperexpanded motor units. Preterminal, intranodal, and intraterminal sprouting were found to significantly increase from 1 to 6 months following partial denervation. While sprouting was enhanced, the number of terminal branch points per end plate did not change. Following 9 months of partial denervation and overuse, the mean fiber areas significantly decreased as compared to controls. The former muscles were found to contain angulated fibers, group atrophy, and increased levels of axonal sprouting. The number of terminal branches per end plate was now significantly increased over control values, possibly a compensatory response to reduced synthesis of neurotrophic factor(s) and/or transmitter-related components. At 12 months, fiber areas, axonal sprouting, and the number of terminal branches per end plate have all decreased. Degenerating end plates, denervated myofibers, angulated fibers, and group atrophy were observed. It would appear that aging-like changes are occurring earlier in chronically stressed, partially denervated muscles.
在大鼠比目鱼肌术后1、3、6、9和12个月，研究了部分去神经支配对肌纤维横截面积、轴突发芽程度和终板形态的长期影响。部分去神经支配1个月后，I型和II型肌纤维的平均横截面积显著低于假手术对照组；观察到纤维萎缩和肥大。3个月后，我们发现两个实验组之间的平均横截面积纤维面积没有统计学差异。6个月后，纤维面积现在显著大于对照组，这可能是由于剩余的过度扩张运动单位过度使用导致的代偿性工作肥大的结果。发现终末前、结内和终末内发芽在部分去神经支配后1至6个月显著增加。虽然发芽增强，但每个终板的终末分支点数没有变化。部分去神经支配和过度使用9个月后，与对照组相比，平均纤维面积显著减少。发现前者的肌肉含有成角纤维、群组萎缩和轴突发芽水平增加。每个终板的终末分支数现在显著高于对照值，这可能是对神经营养因子和/或递质相关成分合成减少的代偿反应。在12个月时，纤维面积、轴突发芽和每个终板的终末分支数均减少。观察到终板退变、失神经肌纤维、成角纤维和群组萎缩。似乎在长期应激、部分去神经支配的肌肉中，类似衰老的变化出现得更早。
