抗阻训练对增龄大鼠骨骼肌线粒体功能的影响*

目的: 从线粒体动力学的角度,探讨抗阻运动对增龄大鼠骨骼肌线粒体功能的影响。方法: 40只雄性SD大鼠随机分为4组:2月龄安静对照组(C1组)、2月龄抗阻运动训练组(R1组)、6月龄安静对照组(C2组)、6月龄抗阻运动训练组(R2组),每组10只。C1、C2组正常喂养,R1、R2组大鼠进行跑台坡度为35°,速度为15 m/min的抗阻运动,一次跑动15 s,间歇30 s,4次为一组,组间间歇3 min,3组为一次循环,一天为2个循环,循环间歇10 min,每周6 d,共8周。采用Western blot法测定各组大鼠股四头肌线粒体融合蛋白2(Mfn2)、GTP酶1(DRP1) 蛋白含量,使用流式细胞仪测定各组大鼠股四头肌线粒体膜电位(ΔΨm)、活性氧(ROS)和游离钙(Ca²⁺)水平。结果: ① 与C1组相比,R1组大鼠DRP1蛋白升高(P＜0.01)、Mfn2蛋白无显著变化,C2组大鼠DRP1、Mfn2蛋白均降低(P均＜0.01);与C2组相比,R2组大鼠DRP1、Mfn2蛋白均升高(P＜0.01,P＜0.05);与R1组相比,R2组DRP1、Mfn2蛋白均降低(P＜0.01,P＜0.05)。② 与C1组相比,R1组Ca²⁺含量降低(P＜0.01)、C2组Ca²⁺含量升高(P＜0.01);与C2组相比,R2组Ca²⁺含量降低(P＜0.01);与R1组相比,R2组Ca²⁺含量升高(P＜0.01)。③ 与C1组相比,R1组ROS含量有所上升,但无显著性差异,C2组ROS含量升高(P＜0.01);与C2组相比,R2组ROS含量降低(P＜0.01);与R1组相比,R2组ROS含量升高(P＜0.01)。④ 与C1组相比,C2组ΔΨm降低(P＜0.01);与C2组相比,R2组ΔΨm升高(P＜0.01);与R1组相比,R2组ΔΨm有所降低,但无统计学差异。结论: 大鼠增龄过程中股四头肌线粒体出现Ca²⁺堆积、活性氧增多、线粒体膜电位下降、融合蛋白减少等现象,抗阻训练可有效改善这些变化。

Effects of resistance training on mitochondrial function in skeletal muscle of aging rats

Objective: To investigate the effects of resistance exercise on mitochondrial function in skeletal muscle of aging rats. Methods: Forty male Sprague-Dawley rats were randomly assigned to 4 groups, 2-month sedentary control group (C1; n=10), 2-month with resistance training group (R1; n=10), 6-month sedentary control group (C2; n=10), 6-month with resistance training group (R2; n =10 ). Rats in R1 and R2 groups were arranged for resistance training for 8 weeks. This program consisted of interval running on a treadmill, speed 15 m·min^-1, 35° incline, duration 15 s, interval 30 s, 4 times/group, 3 groups/cycle, 2 cycles per day, 6 days per week, a total of 8 weeks. The expressions of mitochondrial fusion protein 2(Mfn2) and dynamin-related protein 1(DRP1) in rat quadriceps were detected by Western blot, and the changes of mitochondrial membrane potential (ΔΨm), reactive oxygen species (ROS) and Ca²⁺ concentration were measured by flow cytometry. Results: ①Compared with C1 group, the expression of DRP1 protein in R1 group was increased (P＜0. 01), and the Mfn2 protein in R1 group had no significant difference, both DRP1 and Mfn2 protein in C2 group were decreased (P＜0. 01);compared with C2 group, the DRP1 and Mfn2 protein in R2 group were similarly increased (P＜0. 01, P＜0. 05);compared with R1 group, the DRP1 and Mfn2 protein in R2 group were both decreased (P＜0. 01). ② Compared with C1 group, the Ca²⁺ content of R1 group was decreased (P＜0. 01) and the Ca²⁺ content of C2 group was increased (P＜0. 01);Compared with C2 group, the content of Ca²⁺ in R2 group was decreased (P＜0. 01);compared with R1 group, the Ca²⁺ content in R2 group was increased (P＜0. 01). ③ Compared with C1 group, the ROS content in R1 group was increased, but there was no significant difference, while the ROS content in C2 group was increased (P＜0. 01);compared with C2 group, ROS content in R2 group was decreased (P＜0. 01); compared with R1 group, the ROS content in R2 group was increased (P＜0. 01). ④ Compared with group C1, the levels of ΔΨm in C2 group was decreased (P＜0. 01);Compared with C2 group, The ΔΨm of R2 group was increased(P＜0. 01); Compared with group R1, the ΔΨm of R2 group was decreased, but there was no statistical difference. Conclusion: During the aging process of rats, mitochondria of quadriceps femoral muscle showed Ca²⁺ accumulation, increased reactive oxygen species, decreased mitochondrial membrane potential, decreased fusion protein and other phenomena, and resistance training could effectively improve these changes.