Resveratrol Up Regulates The Expression Of SIRT1 And Mediates Its Protective Effect On Radiation-induced Myocardial Injury

Background: In recent years,cardiac injury caused by radiation therapy(RT)of thoracic malignant tumors has become the focus of attention,and myocardial injury is one of the common and serious complications after RT.RT-mediated oxidative stress(OS)plays an important role in the pathogenesis of myocardial injury.Resveratrol is a natural non flavonoid polyphenol compound with antioxidant activity.Previous studies have confirmed that resveratrol has a significant protective effect on cardiovascular diseases(CVDs)by regulating SIRT1.However,the role of resveratrol in radiation-induced myocardial injury is still unclear.Objectives: In this study,the radiation-induced myocardium injury model of mouse and the radiation-induced injury model of isolated cells(H9C2 and NIH-3T3)were constructed to clarify the role of resveratrol in myocardial injury and further explore its potential molecular mechanism.Methods: Mice(healthy female C57BL/6 mice aged 6-8 weeks and weighing16-18g)were divided into four groups: control group(control),control+resveratrol group(control+Res),radiation group(RT)and radiation+resveratrol group(RT+Res).RT mice were given a single 8Gy cardiac radiation,and res mice were treated with Resveratrol by gavage(20mg/kg·day)on the day of radiation for 3 months.At 1 and3 months after radiation,the changes of cardiac function were evaluated by cardiac ultrasound,and the heart was extracted for pathological tissue staining(immunofluorescence staining,HE staining,TUNEL staining and Masson staining)to evaluate the expression of SIRT1,the level of oxidative stress,the degree of immersion of inflammatory mediators,apoptosis and fibrosis in myocardial tissue.In the cell model(H9C2 and NIH-3T3 were given a single 8Gy radiation),the expression of SIRT1,oxidative stress,apoptosis and fibrosis were explored by cell counting kit-8(CCK-8)and Western blot,so as to further evaluate the effect of resveratrol.Results:1)In the mouse model of early(One month after radiation)radiation myocardial injury,it was found that compared with the control group,RT mice decreased left ventricular ejection fraction(EF)and ventricular short axis shortening(FS),but there was no significant structural change;There was no significant change in SIRT1 expression(immunofluorescence),while reactive oxygen species(ROS)increased(immunofluorescence),inflammatory mediator IL-1β,IL-6 and TNF-αincreased(immunofluorescence)and apoptosis(TUNEL staining)increased.After resveratrol treatment,RT+Res groups’ EF and FS increased.The expression of SIRT1 in myocardial tissue increased significantly,while ROS,inflammation and apoptosis decreased.2)Three months after radiation,the cardiac ultrasound and histopathological examination of mice were carried out.The results of cardiac ultrasound showed that compared with control group,the cardiac structural parameters of RT group: left ventricular inner diameter(LVID)and volume(LVvol)at the end of systole and diastole increased significantly,and EF and FS decreased significantly.There was no significant change in the expression of SIRT1 in myocardial tissue,but the expression of ROS increased,the level of inflammation and apoptosis increased,cardiomyocyte degeneration and disorder of arrangement(HE staining),and the degree of myocardial fibrosis was significant(Masson staining).Compared with RT group,some structural parameters and cardiac function in RT+Res group were significantly improved,the expression of SIRT1 in myocardial tissue was significantly increased,ROS,inflammatory mediator infiltration and apoptosis were reduced,cardiomyocytes were arranged neatly,and the level of fibrosis deposition was reduced.3)In the radiation-induced H9C2 model,we found that compared with control,the total superoxide dismutase(SOD)enzyme activity of RT group decreased slightly,while the SOD enzyme activity increased significantly after resveratrol treatment,which means the antioxidant activity increased.Western blot showed that compared with control,the expression of SIRT1 in RT group had no significant change,but the expression of apoptosis markers caspase 9 and caspase 3 increased significantly;After treatment with resveratrol,the expression of SIRT1 increased significantly,while the expression of caspase 9 and caspase 3 decreased significantly,and cardiomyocyte apoptosis decreased.4)In the radiation injured NIH-3T3 model,we found that compared with control,the SOD enzyme activity of RT group cells decreased slightly,while the SOD enzyme activity increased significantly after resveratrol treatment.Western blot showed that compared with control,the expression of SIRT1 in RT constituent fibroblasts had no significant change,while the expression of Collagen-I and Collagen-Ⅲ increased significantly;After resveratrol treatment,the expression of SIRT1 increased significantly,while the expression of Collagen-I and Collagen-Ⅲdecreased significantly,and the level of fibrosis decreased.Conclusions: 1)In vivo and in vitro experiments show that resveratrol can reduce the inflammatory response,myocardial fibrosis and myocardial apoptosis after myocardial radiation injury,so as to improve cardiac function.2)In vivo and in vitro experiments showed that resveratrol mediated the protective effect on radiation-induced myocardial injury through up-regulating SIRT1 expression.