The Function And Mechanism Of Higenamine On Anti-Cardiac Fibrosis

Background/Objective: Cardiac fibrosis is a common pathological outcome of various cardiovascular diseases,including myocardial infarction,hypertrophy,and atrial fibrillation,ultimately leading to heart failure.The activation of cardiac fibroblasts is considered as the core link of cardiac fibrosis.Higenamine,as one of the main active cardiotonic components of Aconitum,has long been investigated lots of achievements,such as treatment of arrhythmia,positive inotropic and chronotropic effect,anti-apoptotic and anti-oxidative effect.The effect of higenamine on activation of cardiac fibroblasts,however,remains unclear.In our previous study,we demonstrated that higenamine stimulated beta2-adrenergic receptor(?2-AR),AKT phosphorylation and required PI3 K activation for the cardiac protective and anti-apoptotic in cardiomyocytes.Our present study was to investigate whether higenamine reverses cardiac remodeling in vivo and inhibits the activation of cardiac fibroblasts into myofibroblasts transition in vitro and the relevant mechanisms.The purposes of this study are.1.To prove that HG can inhibit cardiac remodeling and improve cardiac function in vivo;2.To prove that HG can inhibit the activation of cardiac fibroblasts into myofibroblasts;3.To prove that HG inhibits the activation of cardiac fibroblasts which is not related to the signal of ?2-AR,and to preliminarily explore its new pharmacological targets.Methods and Results: Transverse aortic constriction(TAC)was used in vivo to establish chronic pressure overload heart failure model in mice.HG(10mg/kg/day)was administered on the second day after operation.Cardiac ultrasonography was used to detect the changes of cardiac structure and function 10 weeks later.WGA and Mason staining were used to evaluate myocardial hypertrophy and cardiac fibrosis.The expression of ANP,BNP and beta-MHC in cardiac embryos was detected by q RT-PCR.In vitro,primary cardiac fibroblasts and cardiac myocytes of neonatal rats were used to activate cardiac fibroblasts induced by TGF-beta.The expressions of ACTA2,Collagen I,III and Fibronectin were detected by q RT-PCR.The expressions of alpha-SMA phenotype protein and T-Smad and P-Smad pathway protein were detected by Western blotting and cellular immunofluorescence.Ang II was used to induce cardiomyocyte hypertrophy.Cellular immunofluorescence was used to detect the expression of alpha-actin protein and q RT-PCR was used to detect the expression of ANP and BNP.Results: In vivo,HG can improve TAC-induced cardiac dysfunction,inhibit cardiac hypertrophy as well as myocardial interstitial fibrosis,and reduce the overexpression of cardiac embryonic genes.In vitro,HG can inhibit the activation of cardiac fibroblasts induced by TGF-? and the deposition of matrix proteins after activation.This mechanism is not related to the known signal of ?2-AR in cardiac myocytes,but to the classical signal pathway of TGF-?/Smad.HG can inhibit cardiomyocyte hypertrophy induced by Ang II and reduce genes overexpression of cardiac embryonic.Conclusion: This study reveals a few new roles of higenamine in cardiovascular field.higenamine can inhibit myocardial interstitial fibrosis and cardiomyocyte hypertrophy in vivo and in vitro,as well as improve myocardial function.The mechanism of higenamine inhibiting the activation of cardiac fibroblasts is independent with its classical ?2 adrenergic receptor signal.Higenamine inhibits the activation of cardiac fibroblasts and the deposition of extracellular matrix proteins may through the TGF-?/Smad signaling pathway,thus inhibiting myocardial fibrosis.