有氧运动对间歇缺氧小鼠心肌线粒体融合—分裂的影响

【作者】 陈娟；

【导师】 胡玉龙；

【作者基本信息】 扬州大学 ， 运动人体科学， 2018， 硕士

【摘要】 阻塞性睡眠呼吸暂停综合征(obstructive sleep apneahypopnea syndrome,OSAHS)因为睡眠时反复发生的间歇缺氧(chronic intermittenthypoxia,CIH)/复氧,使多器官功能受损,对患者健康和社会经济带来较大危害。研究发现运动对OSAHS患者的多器官功能损伤特别是心功能有明显保护作用,但具体机制不明。目的:探讨有氧运动对间歇缺氧小鼠心脏收缩功能和心肌细胞线粒体融合-分裂的影响。方法:本实验选用雄性6周龄的C57/BL6小鼠,体重为20-30g,共30只。将小鼠随机分为3组:对照组(C组),间歇缺氧组(CIH组),间歇缺氧运动组(CIH+E组),每组10只。采用自行设计电子计算机控制的慢性间歇低氧装置进行CIH造模。C组进行正常饲养5周;CIH组每天进行间歇缺氧处理8小时,共5周;CIH+E组第1周每天进行CIH处理后进行跑台适应性运动,从第2周开始,每天进行8小时CIH处理后进行跑台运动60分钟,适应性及正式运动共5周。实验结束后,采用二维超声心动图检测各组小鼠心功能,测量室间隔厚度(interventrieular septum dimersion,IVS)、左室后壁厚度(left ventricular posterior wall thickness,LVPW)、心脏射血分数(ejection fraction,EF)。透射电镜观察心肌细胞线粒体超微结构和形态,RT-PCR检测线粒体融合相关基因线粒体融合蛋白1(Mitofusin1,Mfn1)、线粒体融合蛋白 2(Mitofusin2,Mfn2),视神经萎缩因子 1(Opticatrophy,Opa1),和线粒体分裂相关基因:动力相关蛋白1(Dynamin-relatedproteinl,Drp1),分裂因子1(Fission1,Fis1)的 mRNA 的表达水平。结果:(1)间歇缺氧使小鼠的IVS变薄,LVPW降低,EF下降,表明CIH使心肌细胞数量损失,心脏收缩功能下降。与C组相比,CIH组LVPWd+IVSd明显降低(P<0.01),EF也明显降低(P<0.05);4周有氧运动使CIH+E组小鼠的心肌细胞损失和心脏收缩功能都有所改善,CIH+E组LVPWd+IVSd比CIH组明显升高(P<0.01),EF值比CIH组明显增高(P<0.01)。间歇缺氧使小鼠的心重/体重比值(Heart weight/body weight ratio,HW/BW)下降,左室重量/胫骨长度(Left ventricular weight/tibia length,LVW/TL)减小,表明CIH使心脏重量发生改变。与C组相比,CIH组HW/BW明显降低(P<0.01),LVW/TL也明显下降(P<0.01);与CIH组相比,CIH+E组HW/BW显著升高(P<0.01),LVW/TL也明显增高(P<0.05),提示间歇缺氧导致心肌细胞坏死和数量减少,心肌重量减少,而4周有氧运动使CIH+E组小鼠的心肌细胞结构发生重构,重量有所改善。(2)线粒体电镜结果显示,CIH使心肌细胞线粒体数量减少、体积减小,线粒体膜破裂,线粒体嵴减少、肿胀,线粒体不再呈封闭的囊状结构,并出现多余空腔;4周的有氧运动使CIH+E组小鼠心肌线粒体数量增加,线粒体膜修复,线粒体嵴排列整齐,对心肌线粒体结构具有改善作用。(3)与C组相比,CIH组的线粒体融合相关基因Mfn2、OPA1明显低于C组(P<0.05,P<0.05),有氧运动使CIH+E组的Mfn1、Mfn2、OPA1比CIH组显著升高(P<0.01,P<0.01,P<0.01)。与C组相比,CIH组的线粒体分裂相关基因Drp1、Fis1显著升高(P<0.01,P<0.01),运动使CIH+E组的Drp1比CIH组明显降低(P<0.05),Fis1比CIH组显著降低(P<0.01)。结论:(1)有氧运动对间歇缺氧小鼠的心脏收缩功能具有保护作用。(2)有氧运动对CIH小鼠心肌细胞线粒体融合有促进作用,对线粒体的分裂有抑制作用,通过介导线粒体功能进而对心肌产生保护作用。更多还原

【Abstract】 Obstructive sleep apnea hypopnea syndrome(OSAHS)could impair the function of multiple organs because of repeated chronic intermittent hypoxia(CIH)/reoxygenation during sleep.Which is harmful to the health and economy of patients.It is found that exercise can protect the function of multiple organs in OSAHS patients,especially the heart fcunction,while the specific mechanism is not clear.Object:To investigate the effects of aerobic exercise on cardiac contractile function and mitochondrial fusion-division of CIH mice.Methods:C57/BL6 mice of 6 weeks old were used in this experiment.The mice were divided into 3 groups randomly:control group(C),intermittent hypoxia group(CIH),intermittent hypoxia plus exercise group(CIH+E),10 mice in each group.A self-designed computer controlled chronic intermittent hypoxia device was used.Group C was treated with normal feeding for 5 weeks.The CIH group was treated with intermittent hypoxia for 8 hours a day for 5 weeks.The CIH+E group were treated with suitability running on treadmill after CIH treatment at the first week.Starting from week 2,this group were treated with 60 minutes of running stage after 8 hours of CIH treatment,total 5 weeks.After the experiment,the cardiac function of each group was measured by two-dimensional echocardiography.The interventricular septal thickness(IVS),left ventricular posterior wall thickness(LVPW),ejection fraction(EF)were measured.Ultrastructure and morphology of mitochondria in cardiomyocytes were observed by transmission electron microscopy(TEM).The expression of mitochondrial fusion(Mitofusin 1(Mfn1),Mitofusin 2(Mftn2),Op-ticatrophylopa(Opal))and fission(dynamic in-related protein 1(Drp1),mitogen 1,Fissionl(Fis1))related genes were detected by RT-PCR.Results:(1)Intermittent hypoxia reduced I VS and EF in mice,suggesting that CIH caused the loss of cardiac myocytes.Compared with C group,LVPWd+IVSd in CIH+E group was significantly lower than that in C group(P<0.01)and EF was significantly lower than that in CIH E group.The cardiomyocyte loss and cardiac contractile function of CIH+E mice were improved by aerobic exercise for 4 weeks.LVPWd+IVSd in CIH+E group was better than that in CIH group.The EF value of(P<0.01)in group A was significantly higher than that in group CIH(P<0.01).Intermittent hypoxia decreased heart weight/body weight ratio(HW/BW)and left ventricular weight/tibia length left ventricular weight/tibia(LVW/TL).Compared with the C group,the HW/BW in the CIH group was significantly lower than that in the C group,and the HW/BW in the CIH group was significantly higher than that in the CIH group.LVW/TL also increased significantly(P<0.05),suggesting that intermittent hypoxia could lead to necrosis and decrease in number and weight of myocardial cells.(2)The results of mitochondrial electron rmicroscope showed that compared with group C,the number of mitochondria decreased,the structure of mitochondria changed;and the number of myocardial mitochondria in CIHH+E group increased after 4 weeks of aerobic exercise.Mitochondrial membrane and mitochondrial crest were repaired to improve the structure of myocardial mitochondria.(3)compared with C group,the mitochondrial fusion related gene Mfn2/OPA1 in CIH group was significantly lower than that in C group(P<0.05,P<0.05).Aerobic exercise significantly increased Mfn1,mfn2,OPA1 in CIH+E group than that in CIH group.Compared with C group,Mfn2,OPA1 in CIH group was significantly higher than that in CIH group.The Drp1 of the CIH+E group was significantly lower than that of the CIH group,and the Drpl of the CIH+E group was significantly lower than that of the CIH group.1 compared with CIH group,P<0.01 was significantly lower than that of CIH group.Conclusion:(1)aerobic exercise has protective effect on cardiac contractile function in intermittent hypoxia mice.(2)aerobic exercise can promote mitochondrial fusion in CIH mice,inhibit mitochondrial division,and protect myocardium by mediating mitochondrial function.更多还原