| Heart failure is a complex clinical syndrome arising from any structural or functional cardiac condition that impairs left ventricular(LV)filling or ejection.The majority of patients with heart failure have a history of hypertension.Hypertension induces a compensatory thickening of the ventricular wall in an attempt to normalize wall stress,which results in LV concentric hypertrophy.This alteration in turn decreases LV compliance and LV diastolic filling.Pressure overload in animal models induced by aortic stenosis results in extensive cardiac fibrosis,associated with fibrous tissue deposition in the cardiac interstitium,accompanied by alterations in the extracellular matrix scaffold,that may contribute to cardiomyocyte disarray,which ultimately leading to heart failure.Liguzinediol is a structural modified drug from ligustrazine.Previous studies have shown that liguzinediol could induce positive inotropic effect on both normal and heart failure rats model.To explore the effect of liguzinediol on pressure overloaded ventricular remodeling in abdominal aortic constriction rats,we measured hemodynamic parameters through multichannel channel physiological recording instrument,changes in myocardial morphology was detected by light and electron microscopy,and the content of collagen was detected by Elisa.The cytokines were examined by radioimmunoassay,and the protein related to hypertrophy was detected by western blot(WB).Methods and results1.Animal preparationMale Sprague Dawley rats weighing 200-250g were fasted for 12h before surgery.Anaesthesia was induced by i.p.injection with chloralhydrate,and the abdominal cavity was opened after disinfection.The abdominal aortic was exposed above the left renal artery and constricted.The sham operation group separation of the abdominal aortic was not ligated.After 1week,survived rats were randomly alloted to 6 groups,each as follows:sham-operated,aortic banding without treatment,aortic banding and captopril treatment with 10 mg·kg-1·d-1,aortic banding and liguzinediol treatment with 5、10、20 mg·kg-1·d-1,10 rats per group.Each drug was given by multiple intragastric administrations every day.2.The effect of liguzinediol on Hemodynamic measurementsEight weeks after the surgery,each rat was anaesthesia with 20%urethane,then the hemodynamic indexes such as systolic blood pressure(SBP),diastolic blood pressure(DBP),mean aortic pressure(MAP),left ventricular end diastolic pressure(LVEDP),maximum rate of LV pressure conreaction/relacation(±dp/dtmax)and heart rate(HR)were measured by RM6240B/C four channel physiological recording instrument.All these indexes display a compensatory increase in myocardial contractility and blood pressure,which was caused by abdominal aortic constriction.These increases in blood pressure and left ventricular pressure could be down-regulated in a dose-dependent manner by liguzinediol without influencing LVEDP.3.The effect of liguzinediol on histomorphology of rats’ heartsThe rats’ hearts were initially perfused with 10 mL of cold normal saline(NS)after death to wash out the blood,and excessive water was drained by filter paper.The hearts and left ventricles were measured to calculate whole-hearted quality index(heart mass index,HMI)and left ventricular mass index(left ventricular mass index,LVMI).Compared with sham operation group,HMI and LVMI in model rats were significantly increased,which illustrated ventricular hypertrophy can be induced by abdominal aortic constriction.The outcome indicated that liguzinediol can reduce the hearts’ afterload of model rats,HMI and LVMI.Myocardial fiber hypertrophy,cytoplasmic red dye,visible focal myocardial fiber degeneration and necrosis,and fibrous connective tissue hyperplasia were observed by hematoxylin-eosin(HE)staining.Liguzinediol can improve the above-mentioned pathological changes with dose-dependent manner.The degree of myocardial fibrosis was observed by Masson staining.The outcome indicated that myocardial fibrosis in model rats was significantly intensified than in the sham operation group;each dose of liguzinediol can decrease the level of myocardial fibrosis and collagen deposition.The effects of 20mg/kg dosage were stronger than other dosages.Myocardial tissue ultrastructure was observed with electronic microscope.The results showed that liguzinediol can mitigate cardiac myofibrillar derangement in abdominal aortic constriction rats,reduce the mitochondrial cristae fracture and vacuolization.4.The effect of liguzinediol on ECM depositionThe content of myocardial tissue hydroxyproline(HYP)was detected by alkaline hydrolysis,and the ratio of Ⅰ/Ⅲ type collagen was examined by Elisa.The outcome indicated that cardiac myocyte hypertrophy,extracellular matrix(ECM)deposition,the increased ratio of Ⅰ/Ⅲ type collagen and the high content of HYP could be seen in abdominal aortic constriction rats.Liguzinediol can reduce ventricular remodeling of model rats through the decreased ratio of/III collagen and low content of HYP.5.The effect of liguzinediol on systemic rennin-angiotensin-aldosterone system(RAAS)The concentrations of rennin,angiotensin Ⅱ(AngⅡ)and aldosterone(ALD)in plasma were measured by radioimmunoassay.The experimental results show that the above indicators in the rat plasma rose after abdominal aortic constriction,and they can be significantly reduced with liguzinediol.The inhibitory effect on ALD with liguzinediol is stronger than others,and it has no influence on PRA.6.The effect of liguzinediol on the production of TGF-β and TNF-aTumor necrosis factor-alpha(TNF-α)and transforming growth factor-β(TGF-β)in rats serum were detected by radioimmunoassay.Results showed that the levels of TNF-α and TGF-β increased in abdominal aortic constriction rats,and they can be significantly reduced by liguzinediol.7.The effect of liguzinediol on the phosphorylation of ERK1/2The apex cordis was stored at-80℃ for examining the expression of p-ERK1/2 and ERK1/2 by western bloting analysis(WB).Abodominal aortic constriction stimulated the ERK1/2 singnaling,resulted in the increase of the ratio of p-ERK1/2 and ERK1/2,which could be inhibited by liguzinediol.ConclusionIn summary,liguzinediol plays a pivotal role in protecting heart from pressure overload-induced left ventricular remodeling by stabilizing the hemodynamic,inhibiting the excessive activation of the neuroendocrine system,attenuating the extent of ECM deposition and decreasing the phosphorylation of ERK1/2 in abdominal aortic constriction rats to influence left ventricular remodeling.It can prevent further deterioration of cardiac function,and it has great significance to reduce the occurrence of heart failure. |
