大负荷运动后不同时相大鼠骨骼肌成肌调节因子MyoD、myogenin表达的变化

Changes in the Protein Expression of MyoD and Myogenin in Rat's Skeletal Muscles after Intensive Exercise

目的:研究力竭游泳运动及恢复期大鼠骨骼肌成肌调节因子MyoD、myogenin蛋白表达的变化,以进一步探讨运动导致的骨骼肌微损伤后的再生修复机制。方法:36只8周龄健康雄性SD大鼠随机分为安静对照组(C)、力竭运动后即刻组(E0)、力竭运动后12h组(E12)、力竭运动后24h组(E24)、力竭运动后48h组(E48)和力竭运动后72h组(E72)6组,每组6只。各力竭运动组进行为期1周的负重力竭性游泳运动,并于末次力竭运动后不同时间点取样。采用SABC-DAB免疫组化方法检测大鼠比目鱼肌和股外侧肌中成肌调节因子MyoD、myogenin蛋白表达。结果:C、E0、E12组大鼠比目鱼肌和股外侧肌未见MyoD与myogenin蛋白表达;E24组比目鱼肌MyoD有一定数目的表达,E48组表达数目较多,E72组有所降低,但仍多于E24组;E24组比目鱼肌myogenin有少量表达,E48组表达量也较少,但比E24组多,E72组表达数目明显增多。阳性细胞核数目(均数/视野)统计结果为:C、E0、E12组比目鱼肌MyoD均为0;E24:7.6个/视野;E48:22.2个/视野(较多);E72:13.1个/视野;C、E0、E12组比目鱼肌myogenin均为0;E24:2.0个/视野;E48:3.2个/视野;E72:12.0个/视野(较多)。大鼠股外侧肌MyoD、myogenin表达趋势与比目鱼肌基本一致。结论:力竭游泳运动及恢复期不同时相,大鼠骨骼肌成肌调节因子MyoD、myogenin蛋白表达呈规律性变化,大鼠比目鱼肌和股外侧肌MyoD蛋白表达量在大负荷运动后48h较高,myogenin蛋白表达量在大负荷运动后72 h较高。

Objective The purpose of this study is to investigate the effects of exhaustive swimming on the expression of the myogenic regulatory factors（myoD and myogenin）in skeletal muscles of rats.Methods Thirty six SD adult male rats were randomly and equally divided in to 6 groups：control group（C）;Immediately after exhaustive exercise（E0）;12 hours after exhaustive exercise（E12）;24 hours after exhaustive swimming（E24）;48 hours after exhaustive swimming（E48）and 72 hours after exhaustive swimming（E72）groups.All exhaustive swimming groups were carried on tail-loaded（3% of body weight）swimming until exhaustion per day,for a total of seven days.After the last exhaustive swimming,the rats were anesthetized intraperitoneally to slaughter,and the soleus and vastus lateralis were taken at different time points.Some were used to fix with 4% paraformaldehyde.The protein expression of myoD and myogenin were detected by immunohistochemistry SABC.Results There were no protein expression of myoD and myogenin in groups C,E0,and E12.After a week of intensive swimming,the myoD clearly expressed in group E24 with a peak in group E48 and decreased in group E72.The myogenin in soleus muscle showed less expression in group E24,and increased in group E48 with a peak in group E72.The number of positive nuclei（/field）of myoD in soleus muscle was zero in groups C,E0 and E12;7.6/field in group E24;22.2/field in group E48 and 13.1/field in group E72.The number of positive nuclei（/field）of myogenin in soleus muscle was also zero in groups C,E0 and E12 groups;2.0/field in group E24;3.2/field in group E48 and 12.0/field in group E72.The expressions of myoD and myogenin in vastus lateralis muscle revealed the similar trend as myoD.Conclusion The results showed that the expression of myogenic regulatory factors myoD and myogenin regularly changed 24h,48h,and 72h after intensive exercise in rats＇ soleus and vastus lateralis.MyoD and myogenin expressed significantly 48 hours and 72hrespectively after intensive exercise.