[Effects of aerobic exercise on Nrf2/GPX4/Ferroptosis pathway in myocardial injury in high-fat diet mice].

Objective: To illuminate the protective effects of pathway in inhibiting ferroptosis by glutathione peroxidase 4 (GPX4) activated by nuclear factor erythroid 2-related factor 2 (Nrf2) during aerobic exercise against myocardial injury in high-fat diet mice. Methods: Forty 5-week-old SPF C57BL/6 male mice were randomly divided into the control group (NC), the exercise group (NE), the high fat group (HC) and the high fat diet with exercise group (HE, began at the same time). There were 10 mice in each group. The mice in the high fat diet group were fed with 60% Kcal SPF high fat model diet. Aerobic exercise was performed using increasing load platform exercise, 5 days /week, 60 min/d, the speed started from 13m/min, and increased by 1m/min every two weeks. Myocardium and blood samples were collected after 14 weeks. Structural changes of myocardial tissues were observed by HE staining. Western blot was used to detect the expressions of Nrf2/GPX4/Ferroptosis related proteins in myocardium. Myocardial peroxide concentration and antioxidant enzyme activity were measured by spectrophotometry. Myocardial mitochondrial 8-hydroxy-2 deoxyguanosine (8-OHdG) and serum insulin were measured by ELISA. Results: Compared with the NC group, there was more lipid accumulation in the myocardial fiber space in the HC group, and the levels of FBG and FINS were increased significantly, while ISI was decreased significantly (P＜0.01). Compared with the HC group, the lipid concentration was decreased in the HE group, and the activities of total antioxidant capacity (T-AOC), total superoxide dismutase (T-SOD) and glutathione (GSH) were increased significantly, while the levels of mitochondrial 8-OHdG and myocardial iron content were decreased (P＜0.01). The expression levels of Ferroportin1 (FPN1), ferritin heavy chain 1 (FTH1), GPX4, glucose transporter (GLUT1) and Nrf2 in the HE group were significantly higher than those in the HC group (P＜0.01). Conclusion: The expression of GPX4 was enhanced by more Nrf2 transposition into the nuclear during aerobic exercise, which inhibited the occurrence of myocardial ferroptosis. The activities of antioxidant enzymes were promoted and inhibited the peroxidation damage of myocardial mitochondria.目的: 探讨核因子E2相关因子2(Nrf 2)激活谷胱甘肽过氧化物酶4(GPX4)抑制铁死亡(Ferroptosis)的通路在有氧运动预防高脂膳食小鼠心肌损伤中的保护作用。方法: 40只5周龄SPF 级C57BL/6雄性小鼠随机分为安静对照组(NC)、运动组(NE)、高脂组(HC)和高脂+运动组(HE,高脂与跑台运动同时开始),每组10只。高脂膳食采用60% Kcal SPF级高脂模型饲料喂养,自由进食。有氧运动采用递增负荷跑台运动,每周5 d,60 min/d,速度从13 m/min开始,每两周速度递增1 m/min。14周后取心肌和血液。HE染色观察心肌组织结构变化。Western blot 检测心肌Nrf2/GPX4/ Ferroptosis相关蛋白表达。分光光度法测定心肌过氧化物浓度和抗氧化酶活性。ELISA法检测心肌线粒体8-OHdG和血清胰岛素水平。结果: 与对照组相比,高脂组的心肌纤维间隙脂质集聚增加,FBG和FINS显著增加,而ISI显著下降(P＜0.01);与高脂组相比,高脂运动组的心肌纤维间隙脂质集聚减少, T-AOC、T-SOD、GSH活性显著增强,心肌线粒体8-OHdG和心肌铁含量降低(P＜0.01),FPN1、FTH1、GPX4、GLUT1和细胞核内Nrf2显著升高(P＜0.01)。结论: 有氧运动可促进小鼠心肌Nrf2转位入核增强GPX4表达,抑制心肌Ferroptosis发生,同时促进心肌抗氧化酶活性,抑制心肌线粒体过氧化损伤。.