胰岛素样生长因子Ⅱ在大鼠骨骼肌运动性损伤再生中的作用

Role of insulin-like growth factor-Ⅱ in the regeneration of skeletal muscle after exercise-induced injury in rats

目的:通过观察大鼠骨骼肌运动损伤后具有修复作用的卫星细胞的增殖变化,探讨施加胰岛素样生长因子Ⅱ对肌肉再生的修复作用。方法:选择2个月龄SD大鼠40只。随机分为两组,实验组20只,对照组20只。将两组大鼠建立7d多次力竭跑台训练致骨骼肌损伤的动物模型,即每天力竭1次,连续7d。首次力竭后第1,3,5天实验组于右侧腓肠肌中部的肌膜下分别注射1mL(300ng)外源性胰岛素样生长因子Ⅱ;对照组注射1mL生理盐水。两组分别在第1次力竭后的第7,9,11,17,24,30天各处死大鼠3只,对两组大鼠骨骼肌行苏木精-伊红染色,以光镜和电镜超微结构观察增殖细胞核抗原表达(增殖细胞核抗原以细胞核出现棕黄色颗粒,增殖细胞核抗原指数以随机记数50个高倍视野下共计500个细胞百分率表示),并进行χ2检验。结果:①两组大鼠腓肠肌光镜观察结果:第1次力竭后的第7,11,17天实验组卫星细胞明显增多;对照组胶原纤维增多;24d实验组肌纤维塑形良好,对照组可见瘢痕愈合。②两组大鼠腓肠肌超微结构电镜观察结果:实验组线粒体形态较正常,糖原颗粒增多,可见新生的肌纤维;对照组可见肌浆网扩张,线粒体肿胀,还有凋亡细胞出现。③两组大鼠腓肠肌免疫组织化学染色观察增殖细胞核抗原的表达:实验组明显高于对照组(χ2=9.023,P<0.05)。结论:胰岛素样生长因子Ⅱ可以促进大鼠运动性骨骼肌损伤后的卫星细胞增殖,并减少瘢痕愈合,表明其对大鼠骨骼肌运动性损伤有加快损伤后修复和促进再生的作用。

AIM： To investigate the repairing effect of insulin-like growth factor- Ⅱ on the regeneration of muscle through observing the proliferative changes of satellite cells, which have the repairing effect, after exercise-induced injury of skeletal muscle in rats. METHODS： Forty SD rats of 2 months old were randomly divided into study group （n=20） and control group （n=20）. All the rats were induced to models of injury of skeletal muscle by multiple exhaustive training of treadmill, once a day for 7 days. In the study group, 1 mL （300 ng） exogenous insulin-like growth factor-Ⅱ was injected into the inferior sarcolemma in the middle of right gastroenemius muscle on the 1^st, 3^rd and 5^th days after the first exhaustion respectively. In the control group, the rats were injected with saline （1 mL）. After exhaustion of the 1^st day, 3 rats in both groups were killed respectively on the 7^th, 9^th, 11^th, 17^th, 24^th and 30^th days, the skeletal muscles in the two groups were treated with haematineeosin staining, the expressions of proliferating cell nuclear antigen （it was identified with the buffy granules in the nucleus, its index was expressed by the percentage of 500 cells counted randomly under 50 high power sights） were observed with the uhrastructure under light microscope and electron microscope, and then analyzed with the X^2 test. RESULTS： ①The observational outcomes of gastrocnemius muscle under light microscope in both groups： On the 7^th, 11^th and 17^th days after the exhaustion on the 1^st day, the satellite cells were obviously increased in the st＇ady group, and the collagen fibers were increased in the control group; On the 24^th day, the shape of muscle fiber was good in the study group, and healing scars could be observed in the control group. ②The observational outcomes of the uhrastructure of gastrocnemius muscle under electron microscope in both groups： In the study group, the form of mitochondrion was normal, glucogen granules were increased, and new muscle fibers were observed; In the control group, expanding of sarcoplasmic reticulum, swelling mitochondrion and apoptotic cells were observed. ③The expression of proliferating cell nuclear antigen in gastrocnemius muscle observed with immunohistochemical staining： It was obviously higher in the study group than in the control group （X^2=9.023, P 〈 0.05）. CONCLUSION： Insulin-like growth factor-Ⅱ can accelerate the proliferation of satellite cells, and reduce the healing of scars after exercise-induced injury of skeletal muscle in rats, it indicates that it plays a role in accelerating postinury repair and promoting regeneration after exercise-induced injury of skeletal muscle in rats.