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目的:观察游泳运动对老龄小鼠骨骼肌收缩蛋白基因表达的影响。方法:2月龄雌性ICR小鼠8只(C2),10月龄雌性ICR小鼠32只随机分为10月龄对照组(C10)、12月龄对照组(C12)、12月龄每日运动组(共10周,S1)和12月龄隔日运动组(共10周,S2)(分组命名以取材时间为准)。实验结束后取右侧股直肌,利用RT-PCR方法测定各种收缩蛋白:肌球蛋白重链各亚型(Ⅰ、Ⅱa、Ⅱb、Ⅱx型)及肌动蛋白(α-actin)基因(mRNA)的表达。结果:C10组股直肌Ⅱa型MHC表达显著上升而Ⅱx型则显著下降(P<0.05)。C12组Ⅱb型MHC的表达则较C10组有明显的下降(P<0.01)。两运动组Ⅱa型MHC的表达均比C12组有明显的提高(P<0.01),Ⅱx型则均显著下降(P<0.01)。S2组α-actin表达低于S1组(P<0.05),Ⅱa型MHC则显著高于S1组(P<0.01)。结论:增龄使小鼠股直肌中Ⅱb-MHC和Ⅱx-MHC均出现下调,而Ⅱa-MHC则出现上调。游泳运动可分别使Ⅱa-MHC和Ⅱx-MHC出现明显的上调和下调。
Objective: To observe the effects of swimming exercise on skeletal muscle contractile protein gene expression in aged mice. Methods: Eight female ICR mice of 2 months old (C2) and 32 female ICR mice of 10 months old were randomly divided into 10-month-old control group (C10), 12-month-old control group (C12) Exercise group (10 weeks, S1) and 12-month-old interval exercise group (10 weeks, S2). At the end of the experiment, the right rectus femoris was taken and the contractile proteins were determined by RT-PCR: myosin heavy chain isoforms (Ⅰ, Ⅱa, Ⅱb, Ⅱx) and actin (α-actin) mRNA) expression. Results: The expression of MHC Ⅱa increased significantly in rectus femoris and decreased in type Ⅱx (P <0.05). The expression of MHC Ⅱb in C12 group was significantly lower than that in C10 group (P <0.01). The expression of type IIa MHC in both exercise groups was significantly higher than that in C12 group (P <0.01), and in type IIx group was significantly decreased (P <0.01). The expression of α-actin in S2 group was lower than that in S1 group (P <0.05), while MHC class Ⅱ a was significantly higher than that in S1 group (P <0.01). Conclusion: The age-dependent changes of Ⅱb-MHC and Ⅱx-MHC in the rectus femoris of mice were both down-regulated and Ⅱa-MHC up-regulated. Swimming can make Ⅱ a-MHC and Ⅱ x-MHC significant up-regulation and down-regulation.