耐力运动训练通过SIRTl信号通路保护力竭运动大鼠心肌

SIRT1 signaling pathway mediated the protective effects on myocardium of rats after endurance training and acute exhaustive exercise

目的观察力竭运动模型大鼠耐力运动训练后心脏沉默信息转录调控因子1（SIRTl）、乙酰化叉头转录因子1（Ac-FOX01）的表达变化，探讨耐力运动训练心肌保护的作用机制。方法将雄性Wistar大鼠按完全随机法分为4组，即对照组（n=20）、力竭运动组（力竭组，n=20）、耐力运动训练＋力竭运动组（TE组，n=18）、耐力运动训练＋Sirtinol（选择性SIRTl抑制剂）＋力竭运动组（TSE组，n=17）。对照组和力竭组大鼠常规饲养5周。TE组和TSE组大鼠进行5周耐力运动训练（游泳），TSE组大鼠运动前30min腹腔注射Sirtinol（2mg／kg）。5周后，力竭组、TE组和TSE组大鼠各进行一次性力竭游泳运动。于力竭运动后留取各组大鼠心肌组织，分别采用实时荧光定量逆转录聚合酶链反应及Westernblot法检测心肌SIRTlmRNA和蛋白表达，Westernblot法检测心肌Ac-FOX01、抗凋亡蛋白Bcl-2和促凋亡蛋白Bax的表达，TUNEL法检测心肌细胞凋亡指数。结果（1）各组大鼠心肌组织SIRTlmRNA和蛋白表达：力竭组大鼠心肌组织SIRTlmRNA表达水平明显低于对照组（P〈0．01），TE组则明显高于力竭组（P〈0．01），TSE组又明显低于TE组（P〈0．01）。力竭组大鼠心肌组织SIRTl蛋白表达水平明显低于对照组（P〈0．01），TE组则明显高于力竭组（P〈0．01），TSE组又明显低于TE组（P〈0．01）。（2）各组大鼠心肌组织Ac-FOX01、Bcl-2和Bax的蛋白表达：力竭组大鼠心肌组织Bcl-2表达水平明显低于对照组（P〈0．01），Ac-FOX01和Bax则均明显高于对照组（P均〈0．01）。TE组大鼠心肌组织Bcl-2蛋白表达水平则明显高于力竭组（P〈0．01），Ac-FOX01和Bax均明显低于力竭组（P均〈0．01）。TSE组大鼠心肌组织Bcl-2蛋白表达水平又明显低于TE组（P〈0．01），Ac-FOX01和Bax均明显高于TE组（P均〈0．01）。（3）各组大鼠心肌细胞凋亡指数：力竭组大鼠心肌细胞凋亡指数明显大于对照组[（42．10±1．47）％比（17．31±1．32）％，P〈0．01]，TE组[（15．69±1．81）％]则明显小于力竭组（P〈0．01），而TSE组[（35．34±1．36）％]又明显大于TE组（P〈0．01）。结论耐力运动训练可以激活大鼠心脏SIRTl信号通路，上调SIRTl的表达，调节FOX01的去乙酰化水平，抑制心肌细胞凋亡，从而发挥心肌保护作用。

Objective To detect the expression of SIRT1 and Ac-FOXO1 in rats after endurance training and acute exhaustive exercise, and explicit the myocardial protective effect of SIRT1. Methods Rats were randomly divided into four groups ： control group （ n = 20 ）, exhaustive exercise group （ E group, n = 20）, exhaustive exercise group ＋ endurance training （ TE group, n = 18 ） , exhaustive exercise group ＋ endurance training ＋ selective SIRT1 inhibitor （TSE group, n = 17）. The Control and E groups were fed routinely for 5 weeks. The TE and TSE groups were subjected to swimming exercise for 5 weeks for endurance exercising. The TSE group was intraperitoneally injected with selective SIRT1 inhibitor Sirtinol （2 mg/kg ） at 30 minutes before endurance exercising. The E, TE and TSE groups were subjected to exhaustive exercise. The myocardial tissues of rats were collected after exhaustive exercise. Real-time polymerase chain reaction （PCR） and Western blot analysis were performed to detect the myocardial mRNA and protein expressions of SIRT1 and Ac-FOXO1. The myocardial protein expression of Bax and Bcl-2 was also detected by Western blot. Terminal-deoxynucleoitidyl transferase mediated nick end labeling （TUNEL） assay was used to assess the apoptosis of myocardial cells. Results Compared with Control group, the SIRT1 and Bcl-2 expression in the myocardial tissue was obviously decreased, while the Ac-FOXO1, Bax, and the myocardial cell apoptosis were significantly increased in E group （all P 〈 0. 01 ）. Compared with E group, the expression of SIRT1 and Bcl-2 was obviously up-regulated （ both P 〈 0. 01 ）, while the Ac-FOXO, Bax and the myocardial cell apoptosis was significantly reduced in TE group （ all P 〈 0. 01 ）. Compared with TE group, the SIRT1 and Bcl-2 expression was obviously lower （ both P 〈 0. 01 ）, while Ac-FOXO1, Bax, and the cell apoptosis were significantly higher in group TSE （ all P 〈0. 01 ）. Conclusion Endurance training could protect myocardium by reducing the myocardial oxidative stress injury and apoptosis via activating SIRT1 signaling pathway, up-regulating the myocardial expression of SIRT1 and regulating the deacetylation of FOXO1.