Study On The Effect And Mechanism Of Guanxin V In Regulating Ventricular Remodeling After AMI By Regulating TGF?/Smad Signal Pathway

Background and objectiveAcute myocardial infarction(AMI)is a serious subtype of coronary heart diseases with an extremely high mortality.AMI-induced pathological changes can result in the onset of ventricular remodeling(VR),which further increases the risks of heart failure,malignant arrhythmia,and even cardiac death.Guanxin V is produced by the Nanjing Hospital of Chinese Medicine,Affiliated to Nanjing University of Chinese medicine,which is a commonly used hospital preparation.Our previous evidences have shown that Guanxin V can significantly enhance hemodynamic indexes,reduce serum inflammatory factor levels,inhibit the activation of the renin-angiotension-aldosterone system(RAAS)in AMI rats,thus protecting cardiac function,and alleviating the onset of VR at post-AMI.Nevertheless,the underlying mechanism of Guanxin V in regulating VR at post-AMI is largely unclear.This study aims to investigate how Guanxin V protects VR at post-AMI and the molecular mechanism,which provides theoretical references for the treatment of VR at post-AMI with the traditional Chinese medicine.Methods(1)Sixty male Syrian hamsters(110±20 g,8 weeks old)were used for the generation of the in AMI model by performing the ligation of the left anterior descending coronary artery(LAD).According to the postoperative survival,the hamsters were randomly divided into four groups,namely Sham operation group(n=12),AMI group(n=12),Guanxin V group(GX 6g/Kg/d,n=12)and Tranilast group(Tra 105mg/Kg/d,n=12).Hamsters in AMI group,GX group and Tra group were operated by LAD to establish the AMI.Hamsters in GX and Tra group received intragastrical administration of 6 g/Kg/d Guanxin V,and 105 mg/Kg/d Tranilast,respectively,while the remaining were administrated with the same volume of normal saline once daily.Body weight was recorded at an indicated time point per week.Six randomly selected hamsters per group were sacrificed at the 4th and 8th week after administration,respectively after electrocardiography,and blood sample collection(4 ml)from the aorta abdominalis.The heart was harvested,weighed and stored for use.(2)Relative levels of renin,Chymase,Ang ? and Ang ? in serum and heart tissues were examined by ELISA.Protein levels of Chymase and AT1R in heart tissues were detected by Western blot.Positive expressions of Chymase and AT1R in heart tissues were measured by immunohistochemical(IHC)staining,thus investigating the role of Guanxin V in activating the RAAS in hamsters at post-AMI.(3)Heart morphology was assessed by H&E staining.The fibrotic level of the heart was observed by Masson staining.Positive expressions of collagen I and III were evaluated by IHC staining.Toluidine blue(TB)staining was performed to assess the degree of mast cell aggregation.In addition,protein levels of TGF-?1,Smad2/3,pSmad2/3 and Smad7 in heart tissues were determined by Western blot,thus investigating the role of Guanxin V in mediating cardiac fibrosis of hamsters at post-AMI and the underlying mechanism.(4)The myocardial infarction area was stained by TTC staining.TUNEL assay was performed to assess the apoptotic level of cardiomyocytes in hamsters.In addition,protein levels of Caspase3 and Bcl-2 were examined by Western blot,thus investigating the role of Guanxin V in mediating cardiomyocyte apoptosis in hamsters at post-AMI and the underlying mechanism.Results(1)Guanxin V significantly reduced left ventricular end-systolic inner diameter(LVIDs)and left ventricular end diastolic volume(LVEDV),and improved cardiac function in hamsters at post-AMI.(2)Guanxin V significantly reduced heart weight index and myocardial infarction size in hamsters at post-AMI.(3)Guanxin V significantly reduced the degree of cardiac fibrosis in hamsters at post-AMI.(4)Guanxin V significantly inhibited the activation of the RAAS in hamsters at post-AMI.(5)Guanxin V significantly reduced the aggregation of mast cells in hamsters at post-AMI.(6)Guanxin V significantly inhibited the activation of the TGF?/Smad signaling pathway in hamsters at post-AMI.(7)Guanxin V significantly inhibited cardiomyocyte apoptosis and downregulated Caspase3 and Bcl-2 in hamsters at post-AMI.ConclusionsGuanxin V inhibits cardiac fibrosis,intervenes VR at post-AMI in hamsters by downregulating Chymase,inhibiting the aggregation of mast cells and the activation of the RAAS via inactivating the TGF?/Smad signaling pathway.Moreover,Guanxin V also reduces cardiomyocyte apoptosis,and alleviates VR at post-AMI in hamsters by downregulating Caspase3 and Bcl-2.