| Objective To investigate the effect of aerobic exercise on the improvement of cardiac function in mouse with heart failure(HF)after myocardial infarction(MI)and its potential mechanisms,so as to provide a theoretical basis for the clinical treatment of HF after MI.Methods A mouse model of HF after MI was surgically constructed,and aerobic exercise(Ex)intervention was performed.The mice were divided into sham-operatedgroup(Sham group),HF after MI group(HF group),and HF+Ex group(HF+Ex group).A model of H2O2-induced cardiomyocyte injury was established by treating rat H9C2 cardiomyocytes with H2O2,and the effect of cardiomyocyte exercise was simulated by treatment with AMP-activated protein kinase(AMPK)agonist AICAR,Cells were divided into control group,H2O2-induced group(H2O2 group),H2O2-induced+vector group(H2O2+vector group),H2O2-induced+OE-Dhcr24 group(H2O2+OE-Dhcr24 group),H2O2-induced+AlCAR group(H2O2+AICAR group),H2O2-induced+negative control siRNA group(H2O2+siNC group),H2O2-induced+Dhcr24 siRNA group(H2O2+siDhcr24 group),H2O2-induced+AICAR+siNC group(H2O2+AICAR+siNC group),H2O2-induced+AlCAR+siDhcr24 group(H2O2+AlCAR+siDhcr24 group).ELISA was used to measure the serum levels of brain natriuretic peptide(BNP)in mice.Ultrasound Cardiogram(UCG)was used to detect the left ventricular end-systolic dimension(LVEDs),left ventricular end-diastolic dimension(LVEDs),ejection fraction(EF)and fractional shortening(FS)in mice.Hematoxylin-eosin staining(HE)was used to observe myocardial injury in mice.Masson’s trichrome staining(Masson)was used to detect myocardial fibrosis in mice.TdT-mediated dUTP nick end labeling(TUNEL)was applied to detect apoptosis levels in myocardial tissue and cardiomyocytes.Western blot was used to detect the expression of Bcl2-Associated X(BAX),B-cell lymphoma-2(Bcl-2)and 24-dehydrocholesterol reductase(Dhcr24)in myocardial tissue and cardiomyocytes.The apoptosis level in cardiomyocytes were detected by flow cytometry(FCM).The morphological changes in cardiomyocytes were observed by microscopy.Cell Counting Kit-8(CCK-8)was used to detect the cell viability.Immunofluorescence technique(IF)was used to detect the expression of Dhcr24 in cardiomyocytes.Results(1)Serum BNP levels(P<0.001),LVEDs,and LVEDd were significantly higher(P<0.01),while EF and FS were significantly lower(P<0.01)in the HF group compared with the Sham group.Compared with the HF group,the Ex intervention significantly decreased serum BNP levels(P<0.001),LVEDs and LVEDd(P<0.01),while significantly increased EF and FS(P<0.01)in the HF+Ex group.(2)HE and Masson staining results showed extensive necrosis with extensive collagen deposition in the HF group,whereas necrosis and collagen deposition were significantly reduced in the HF+Ex group.(3)TUNEL showed that myocardial tissue apoptosis levels were increased in the HF group compared to the Sham group,while the Ex intervention reduced myocardial apoptosis.(4)Results of Western blot showed that BAX expression was increased and Bcl-2 expression was decreased in the HF group compared with the Sham group.The HF+Ex group inhibited the expression of BAX and elevated the expression of Bcl-2 compared with the HF group.(5)Western blot showed that Dhcr24 expression was decreased in the HF group compared with the Sham group,while the Ex intervention up-regulated Dhcr24 expression in the HF+Ex group compared with the HF group.(6)FCM and TUNEL results showed that H2O2 treatment up-regulated the apoptosis level of cardiomyocytes compared with the control group.(7)Western blot showed that H2O2 treatment up-regulated BAX expression and decreased Bcl-2 expression.(8)Microscopic observation showed-that cardiomyocytes in H2O2 group showed cell contraction,cell shape change and cell gap widening.morphological damage of cardiomyocytes was improved after upregulating Dhcr24 expression.(9)The results of CCK-8 exhibited that cell viability was significantly lower in the H2O2 group compared with the control group(P<0.001),while overexpression of Dhcr24 significantly increased cell viability(P<0.01).(10)FCM and TUNEL assays revealed that AICAR treatment reduced the apoptosis level in H2O2-induced cardiomyocytes.(11)The results of Western blots showed that BAX expression was decreased and Bcl-2 expression was increased in cardiomyocytes of H2O2+AICAR group compared with H2O2 group.(12)IF experiments showed that the expression of Dhcr24 was higher in cardiomyocytes of H2O2+AICAR group compared with H2O2 group.(13)Western blot showed that Dhcr24 expression was elevated in cardiomyocytes of the H2O2+AICAR group compared with the H2O2 group.(14)Both FCM and TUNEL assays showed that the apoptosis level was increased in the H2O2+AICAR+siDhcr24 group compared with the H2O2+AlCAR+siNC group.Conclusion(1)Aerobic exercise improves cardiac function in HF after MI mice;(2)Aerobic exercise can inhibit the level of H2O2-induced apoptosis in cardiomyocytes by upregulating the expression of Dhcr24. |
