1.无;2.Wu Han Sport University
The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
目的 探讨中等有氧运动和高强度间歇运动对非酒精性脂肪肝小鼠心肌线粒体自噬的影响及可能机制。方法 将40只3周龄雄性C57BL/6J小鼠随机分为普通饲养组（Chow组，n=10）和高脂饲养组（HFD组，n=30）。第18周，将HFD组体重超过普通饮食组20%~30%（包含 20%）者判定为肥胖小鼠（n=26），通过随机抽选2只小鼠做肝脏油红O染色，确定NAFLD小鼠模型建立成功。随机筛选出16只NAFLD小鼠分成中等强度有氧运动组（MICT组）和高强度间歇有氧运动组（HIIT组），每组8只，分别对两组进行8周的运动训练，干预结束后称重取材。Masson染色观察心肌纤维化情况；透射电镜观察心肌细胞超微结构；Western Blot检测心肌中线粒体自噬和线粒体生物发生等相关蛋白表达。结果 ⑴与Chow组相比，HFD组体重显著增加、心指数明显下降；与HFD组相比，MICT和HIIT组体重明显增加、MICT组心指数上升。⑵ Masson结果显示，与Chow组相比，HFD组心肌内胶原纤维含量显著增加，且电镜下心肌肌纤维排列杂乱、断裂，心肌形态杂乱不堪，线粒体肿胀、嵴发生断裂且模糊不清并夹杂多个脂滴；与HFD组相比，MICT组和HIIT组心肌内胶原纤维含量显著性减少，透射电镜下心肌肌纤维排列略有恢复，z线清晰可见，线粒体变性程度略有改善，且脂滴也略有减少，其中，MICT组对心脏组织结构改善效果优于HIIT组。⑶Western Blot结果显示，与Chow组相比，HFD组心肌组织中PINK1和Beclin1表达水平无明显变化，Parkin、LAMP1和PGC-1α表达显著下降（p<0.01），p62蛋白表达和LC3-II/LC3-I比值显著升高（p<0.05，p<0.01）；与HFD组相比， MICT和HIIT组PINK1和Beclin1表达水平无明显变化，PGC-1α表达呈上调趋势，其中MICT组Parkin、LAMP1表达显著升高(p<0.05)， p62蛋白表达和LC3-II/LC3-I比值明显降低（p<0.05，p<0.01），HIIT组Parkin、LAMP1表达水平具有上调趋势，LC3-II/LC3-I比值和p62蛋白表达明显降低（p<0.05，p<0.01）。结论 不同方式有氧运动均能有效改善NAFLD小鼠心肌结构和功能损伤，其作用途径可能是通过刺激心肌细胞内线粒体自噬通量，激活自噬，恢复细胞正常自噬功能，从而改善心肌细胞损害，且中等连续有氧运动改善效果更佳。
Objective To investigate the effects of moderate aerobic exercise and high intensity intermittent exercise on myocardial mitochondria autophagy in mice with non-alcoholic fatty liver disease and its possible mechanism. Methods Forty 3-week-old male C57BL/6J mice were randomly divided into normal feeding group (Chow group, n=10) and high fat feeding group (HFD group, n=30). At week 18, those whose body weight in HFD group exceeded 20%~30% (including 20%) of the ordinary diet group were judged as obese mice (n=26). Two mice were randomly selected for liver oil red O staining to confirm the successful establishment of NAFLD mouse model. Sixteen NAFLD mice were randomly selected and divided into moderate intensity aerobic exercise group (MICT group) and high intensity intermittent aerobic exercise group (HIIT group), with 8 mice in each group. The two groups were given exercise training for 8 weeks, respectively, and the samples were weighed after intervention. Masson staining was used to observe myocardial fibrosis. The ultrastructure of myocardial cells was observed by transmission electron microscopy. Mitochondrial autophagy and mitochondrial biogenesis were detected by Western Blot. Results ⑴ Compared with Chow group, body weight and heart index in HFD group were significantly increased and decreased. Compared with HFD group, the body weight of MICT and HIIT group increased significantly, and the heart index of MICT group increased. (2) Masson results showed that compared with Chow group, the content of collagen fibers in myocardium in HFD group was significantly increased, and the myocardial fibers were disorganized and broken under electron microscope. The morphology of myocardium was disorganized, mitochondria were swollen, crists were broken and blurred, and lipid droplets were included. Compared with HFD group, the myocardial collagen fiber content in MICT and HIIT groups was significantly reduced, the myocardial fiber arrangement was slightly recovered under transmission electron microscopy, the Z-line was clearly visible, the degree of mitochondrial degeneration was slightly improved, and the lipid droplets were also slightly reduced. Among them, the improvement effect of MICT group on the cardiac tissue structure was better than that of HIIT group. (3) Western Blot results showed that compared with Chow group, the expression levels of PINK1 and Beclin1 in myocardial tissue of HFD group had no significant changes, while the expressions of Parkin, LAMP1 and PGC-1α were significantly decreased (p<0.01). p62 protein expression and LC3-II/LC3-I ratio were significantly increased (p<0.05, p<0.01); Compared with HFD group, the expression levels of PINK1 and Beclin1 in MICT and HIIT groups were not significantly changed, while the expression of PGC-1α was up-regulated, and the expressions of Parkin and LAMP1 in MICT group were significantly increased (p<0.05). p62 protein expression and LC3-II/LC3-I ratio were significantly decreased (p<0.05, p<0.01), Parkin and LAMP1 expression levels were up-regulated, LC3-II/LC3-I ratio and p62 protein expression were significantly decreased in HIIT group (p<0.05, p<0.01). Conclusion Different forms of aerobic exercise can effectively ameliorate myocardial structural and functional injury in NAFLD mice, which may be through stimulating the autophagy flux of mitochondria in cardiomyocytes, activating autophagy and restoring the normal autophagy function of cells, so as to ameliorate myocardial cell damage, and moderate continuous aerobic exercise has better improvement effect.