Protective Effect And Mechanism Of LCZ696 In Rats With Doxorubicin-induced Myocardial Fibrosis

Objective:To investigate the protective effect on myocardium and the regulation of sodium channel expression and its possible mechanism of LCZ696 in rats with doxorubicin-induced myocardial fibrosis by observing PKC/ROS signaling pathway.Methods:40 male SD rats were randomly divided into the control group(n=10)and the model group(n=30)after 1 week’s adaptive feeding.The model of myocardial fibrosis was established by intraperitoneal injection of doxorubicin in the model group for 3 times a week for 2 weeks.After 3 weeks,the model group was randomly divided into doxorubicin group(DOX group),LCZ696 intervention group(ARNI group)and LCZ696+PKC agonist intervention group(PMA group)with 10 rats in each group.ARNI group and PMA group were gavaged with LCZ696 suspension for 4 weeks,while PMA group were injected intraperitoneally with PMA every other day 2 weeks later.4 weeks later,cardiac systolic function was recorded by echocardiography.The morphological changes of myocardial tissue were observed by HE staining,and the content of myocardial collagen was detected by Masson staining.The content of reactive oxygen species in cardiomyocytes was detected by ROS fluorescence probe-DHE.Apoptosis in cardiomyocytes was observed by TUNEL fluorescence staining.The activity of SOD in myocardial tissue was determined using the xanthine oxidase method and the content of GSH in myocardial tissue was determined using the micro-enzyme method.The levels of cleaved caspase-3,Bcl-2,Nav1.5 and PKC in rat heart tissue were measured by Western Blot.Results:Compared with DOX group,the level of myocardial fibrosis in ARNI group decreased,the levels of CVF,NT-proBNP,ROS,apoptosis rate,cleaved caspase-3,and PKC decreased(P<0.05),while the levels of LVEF,LVFS SOD,GSH,Bcl-2,and Nav1.5 levels increased(P<0.05).Compared with the ARNI group,the level of myocardial fibrosis increased in the PMA group(P<0.05),and CVF,NT-proBNP,ROS,apoptosis rate,cleaved caspase-3,and PKC levels increased(P<0.05),and LVEF,LVFS,SOD,GSH,Bcl-2,and Nav1.5 levels decreased(P<0.05).Conclusion:1.PKC/ROS signaling pathway may be involved in doxorubicin-induced oxidative stress and apoptosis,myocardial fibrosis and regulation of myocardial sodium channel expression in rats.2.LCZ696 may inhibit PKC/ROS signaling pathway to attenuate the levels of oxidative stress and apoptosis to improve myocardial fibrosis and cardiac function in rats with doxorubicininduced myocardial fibrosis,and exerts certain cardioprotective effects in doxorubicin cardiomyopathy.3.LCZ696 may inhibit PKC/ROS signaling pathway to upregulate myocardial Nav1.5 expression level in rats with doxorubicin-induced myocardial fibrosis,which may be its potential molecular mechanism of antiarrhythmia.