过量运动对肌营养不良模型鼠骨骼肌的损害作用

目的:观察过量运动对Duchenne型肌营养不良症模型鼠(mdx鼠)骨骼肌组织的影响。方法: 让成年和老年mdx小鼠、成年和老年C57小鼠连续进行游泳和提尾倒立运动试验(对照mdx不作运动), 每天1次, 每次13min, 连续3d后, 鼠尾静脉注谢Evans蓝, 次日杀小鼠, 剥去皮肤, 观察mdx鼠、C57鼠全身骨骼肌颜色改变, 对比照相后, 取腓肠肌、膈肌作冰冻切片, 荧光显微镜下, 观察Evans蓝的染色范围, 再作常规HE染色, 光学显微镜下, 观察骨骼肌细胞的组织学改变。结果:肉眼可见运动后的mdx鼠骨骼肌许多部位呈纵形条状蓝色, 而对照mdx鼠和C57鼠几乎无Evans蓝染色;荧光显微镜下, 运动后的mdx鼠骨骼肌可见Evans蓝荧光, 对照mdx鼠偶见此荧光, 而C57鼠无此荧光。光学显微镜下, 可见mdx鼠骨骼肌细胞变大、变圆, 伊红浓染, 胞核致密粗大, 坏死的肌细胞胞内结构降解, 呈无定型结构。膈肌中可见变性坏死的肌纤维居多, 而C57鼠无此改变。结论:过量运动造成了mdx鼠骨骼肌的损害;Evans蓝染色有助于鉴别变性坏死的肌纤维和研究dystrophin缺乏的肌肉的变性过程。

Skeletal muscles of mdx mice were damaged after overload exercise

AIM: To observe the effects of overload exercise on skeletal muscles in X-linked muscular dystrophy(mdx) mice.METHODS: Mdx mice and C57 mice were carried out swimming and hanging tail movement tests (mdx mice as control did not exercise). It lasted for 13 minutes each time per day, and lasted 3 days. Evans blue was injected into tail vain. The mice were killed the next day, and the hind limbs were taken photographs after skins were flayed. The gastrocnemius muscles and diaphragms cryostat sections were made. Under a fluorescence microscope, Evans blue staining was seen. Then the sections were tested by routine HE staining, the histological change of muscles was analyzed under a light microscope.RESULTS: Many blue colored longitudinal lines were observed in skeletal muscles of mdx mice, whereas they were hardly seen in control mdx and C57 mice. Under a fluorescence microscope, some muscle fibers of mdx mice were stained with Evans blue, few muscle fibers of control mdx mice were stained, and C57 mice were not. Under a light microscope, HE staining of muscles showed some degenerated muscle fibers became round in shape and the myonuclei became condensed, or necrotic fibers had amorphous structures, most of them in the degenerated and necrotic fibers of diaphragms C57 mice did not have these changes.CONCLUSION: Overload exercise did harm to skeletal muscles of mdx mice; Vital staining with Evans blue is useful not only for distinguishing degenerating muscle fibers, but also for studying the degeneration process in dystrophin-deficient muscle.