Nishizawa Tomie, Tamaki Hiroyuki, Kasuga Norikatsu, Takekura Hiroaki
Department of Physical Education, Chukyo Women's University Junior College, Obu, Aichi 474-0011, Japan.
J Muscle Res Cell Motil. 2003;24(8):527-37. doi: 10.1023/b:jure.0000009905.89618.33.
We evaluated the degeneration and regeneration of neuromuscular junctions (NMJs) on the extensor digitorum longus muscle of Fischer 344 rats between 4 h and 3 weeks after bupivacaine hydrochloride (BPVC) injection, which induces muscle fiber necrosis, using histochemical staining by acetylcholine esterase (AchE)-silver and electron microscopy. Degeneration of muscle fibers and NMJs was observed 4 h after BPVC injection. One week after BPVC injection, some terminal axons were almost completely retracted, and the level of basal lamina-associated AchE in some NMJ regions had gradually disappeared. At that time, the depression contained a few, mostly pit-like or elongated oval invaginations: the incipient junctional folds and some NMJs did not have any secondary junctional fold. By 2 weeks after the BPVC injection, secondary junctional folds began to develop: however, the number of secondary junctional folds was clearly less than that in normal NMJs. At 3 weeks when regeneration of muscle fibers was well advanced, the staining for AchE at the end-plates became stronger and better-defined. The volume density of mitochondria in the terminal area of the terminal significantly decreased upon BPVC-induced destruction of the NMJ, and the density reached the lowest value 24 h after BPVC injection. Significant changes in the ultrastructural features of the architecture of NMJs occurred in skeletal muscle fibers damaged by BPVC during both the degeneration and regeneration processes. The changes in the ultrastructural and morphological features of the NMJ architecture during the regeneration of degenerated muscle fibers resembled those that occur during the differentiation of normal muscle fibers.
我们使用乙酰胆碱酯酶（AchE）-银组织化学染色和电子显微镜，评估了盐酸布比卡因（BPVC）注射后4小时至3周之间，Fischer 344大鼠趾长伸肌神经肌肉接头（NMJ）的退变和再生情况。BPVC注射可诱导肌纤维坏死。BPVC注射后4小时观察到肌纤维和NMJ的退变。BPVC注射后1周，一些终末轴突几乎完全回缩，一些NMJ区域中与基膜相关的AchE水平逐渐消失。此时，凹陷处有一些，大多是坑状或细长椭圆形的内陷：初期的突触褶皱，一些NMJ没有任何次级突触褶皱。BPVC注射后2周，次级突触褶皱开始形成：然而，次级突触褶皱的数量明显少于正常NMJ。在3周时，肌纤维再生进展良好，终板处的AchE染色变得更强且更清晰。BPVC诱导NMJ破坏后，终末区域线粒体的体积密度显著降低，且在BPVC注射后24小时密度达到最低值。在退变和再生过程中，BPVC损伤的骨骼肌纤维中NMJ结构的超微结构特征发生了显著变化。退变肌纤维再生过程中NMJ结构的超微结构和形态学特征变化类似于正常肌纤维分化过程中发生的变化。
