大鼠失神经不同时相的骨骼肌形态和MyoD表达变化

Changes in the protein expression of Myo D and the skeletal muscles morphology of rats after denervation in different time phases

目的研究大鼠失坐骨神经后Myo D在腓肠肌中不同时相的表达变化,进一步探讨骨骼肌失神经后再生修复机制。方法将48只2月龄SD雄性大鼠随机分为八组,每组6只。其中正常对照和失神经各四组,于术后2、7、14、28 d取材,分别标记为Z1、Z2、Z3、Z4组和S1、S2、S3、S4组。在相应的时相内取各组大鼠左、右后肢的腓肠肌测肌湿重后冻存以备后续实验。计算各组腓肠肌湿重比及其肌腹段HE染色后的横截面积,Western blotting检测Myo D在腓肠肌的表达。结果手术组失神经侧(S1F右、S2F右、S3F右、S4F右)大鼠腓肠肌湿重逐渐减小,且各时相肌湿重比比较,差异均有统计学意义(P<0.05);HE染色后腓肠肌的各时相平均横截面积逐渐减小,即各时相组内与组间比较,差异均有统计学意义(P<0.05);Western blotting检测各时相失神经侧较正常对照组腓肠肌的Myo D表达增加,差异有统计学意义(P<0.05)。结论大鼠腓肠肌失坐骨神经后第1周内出现明显肌萎缩现象,且萎缩速度在失神经前2周较快;Myo D蛋白在大鼠失坐骨神经后的表达增加,在失神经第2周时其表达量最高,随后开始降低,但仍高于正常大鼠。

Objective To explore the expression changes of Myo D after losing the sciatic nerve in rats′ gastrocnemius musle at different time phases in order to investigate the skeletal muscle regeneration and repair mechanisms after denervation further. Methods A total of 48 male SD rats aged 2-month-old were randomly divided into 8 groups,6 of each group including the 4 normal control groups and the 4 nerve-lost groups,obtaining the samples after 2,7,14,28 d respectively,marking group Z1,Z2,Z3,Z4 and group S1,S2,S3,S4. It was removed the gastrocnemius muscle from the latter legs of each group in the different time phases to measure their wet muscle weight and then frozed to prepare the following experiements. The wet weight ratio of the gas-trocnemius muscle and the cross-sectional area of musle belly setions stainied by HE. The expression of gastrocnemius muscle was detected by Western blotting. Results The wet musle weight was gradually decreased in the denervation side（S1Fright,S2 Fright,S1Fright,S4Fright） from the operation groups. There were statistically significant compared the wet weight among the above time pahses（P0.05）. The average cross-sectional area after HE staining was declined at different time phases,whose difference had statisti cal significance within the group and among the groups（P0.05）. The denervation sides in various time phases were increased than the normal control groups in Myo D protein by Western blotting. The difference was statistically significant（P0.05）. Conclusion The amyotrophy occurred within 1 week after loseing ischiadic nerve of rats′ gastrocnemius muscle and accelerated in the first two weeks. The Myo D protein expression were increased after loseing their ischiadic nerve. The expression amount reach-es the peak at the second week of denervation,then began to decrease but still higher than controls.