8周有氧运动对Nrf2敲除鼠心肌纤维化的作用及机制

Effects of 8-week Aerobic Exercise Training on the Regulation of Myocardial Fibrosis in Nrf2 Knockout Mice

研究8周有氧运动训练对Nrf2敲除鼠心肌纤维化的作用及机制。方法:8周龄Nrf2敲除鼠和野生鼠各20只,随机分为野生安静组(WC)、野生运动组(WE)、敲除安静组(KC)和敲除运动组(KE),各10只。适应性训练一周后,WE组和KE组小鼠采用动物跑台进行8周训练。方案:坡度为0°,速度为12 m/min,60 min/天,5天/周。训练后48 h,处死所有小鼠取心肌。Westernblot方法测定胶原蛋白(Collagen)、基质金属蛋白酶2(MMP2)、基质金属蛋白酶组织抑制剂(TIMP2)、Nrf2及其下游醌氧化还原酶(NQO1)和血红素加氧酶1(HO-1)蛋白水平,计算MMP2与TIMP2的比例。实验数据采用双因素方差分析,对干预方式和基因型的主效应及交互作用进行分析。结果:各组心脏重量和全心重量指数无显著性差异;KC组和KE组CollagenⅠ表达分别显著高于WC组和WE组;KC组和KE组的MMP2表达分别显著高于WC组和WE组,而KC组和KE组的TIMP2表达分别显著低于WC组和WE组;Nrf2敲除鼠的Nrf2表达显著低于野生鼠,且KC组和KE组的NQO1和HO-1的表达均分别低于WC组和WE组,WE组HO-1表达高于WC组,但KE组与KC组无差异。结论:Nrf2的缺失能够引起胶原蛋白紊乱和MMPs/TIMPs比例失衡,促进小鼠心肌纤维化的进程;有氧运动可增强Nrf2及其下游抗氧化酶表达,这一机制可能在有氧运动改善心肌纤维化过程中起决定性作用。

Objective: To investigate the effects of 8 weeks aerobic exercise training on the regulation of myocardial fibrosis in Nrf2 knockout mice. Methods:Eight weeks old Nrf2 knock out(KO)mice and wild mice were randomly assigned to four groups:wild control group(WC),wild exercise group(WE),KO control group(KC)and KO exercise group(KE),n=10.After one-week adaption,mice in exercise groups underwent 60 min/day treadmill running at speed of 12 m/min for 8 weeks. Cardiac was collected 48 hours after training. The expression of collagen,matrix metalloproteinase 2(MMP2)and tissue inhibitor of metalloproteinase(TIMP2),Nrf2 and its antioxidant-related quinone oxidoreductase(NQO1)and heme oxygenase 1(HO-1)protein was analyzed by Western Blot. And the ratio of MMP2 to TIMP2 was calculated. The experimental data was analyzed by two-way ANOVA,and the main effects of intervention(quietness and exercise training)and different genotypes and the interaction of the two factors were analyzed. Results: There was no significant difference in heart weight and whole body weight index between groups. The expression of Collagen Ⅰ in the control and exercise groups of Nrf2 knockout rats was significantly higher than that in the control and exercise groups of wild rats. The expressions of MMP2 in KC group and KE group were significantly higher than those in WC group and WE group,respectively. The expression of TIMP2 in KC group and KE group was significantly lower than that in WC group and WE group,respectively. The expression of Nrf2 in Nrf2 knockout mice was significantly lower than that in wild mice,and the expressions of NQO1 and HO-1 in KC group and KE group were lower than those in WC group and WE group,respectively. The expression of HO-1 in WE group was higher than WC group. However,there is no difference between the KE group and the KC group. Conclusions: The loss of Nrf2 can cause collagen disorder and imbalance of MMPs/TIMPs,and promote the process of myocardial fibrosis in mice. Aerobic exercise training improves expression of Nrf2 and antioxidant enzymes. This is potential decided regulation signal pathway of aerobic exercise promote myocardial fibrosis.