Decreased expression of neuregulin-1β in myocardium of hypertrophic rats induced by pressure-overloaded

Objective To investigate the expression profile of neuregulin-1β(NRG-1β) at mRNA and protein level in myocardium of hypertrophic rats induced by pressure-overloaded.Methods Wistar rats were randomly divided into four groups:myocardial hypertrophy groups(Model) of 4 weeks and 8 weeks,control operation groups(Control) of 4 weeks and 8 weeks.Model groups were operated with abdominal aortic constriction.Hemodynamic and echocardiogrophic characteristics were evaluated;masson staining was employed to observe the pathological lesions of myocardial tissues;radioimmunological method was used to detect angiotensin Ⅱ(Ang Ⅱ);expression of NRG-1β mRNA and protein in myocardium were tested by real-time PCR and western blot.Results 1) Compared with 4wC,left ventricular ejection fraction(LVEF),left ventricular fraction shortening(LVFS),left ventricular end systolic pressure(LVESP),Maximal rate of increase in left ventricular pressure(±dP/dt max) of 4wM were decreased(P 0.05),while left ventricular end-systolic diameter(LVEDD),left ventricular end-diastolic diameter(LVESD),left ventricular end diastolic pressure(LVEDP),collagen volume fraction(CVF) and Ang Ⅱof 4wM were increased(P0.05,P0.01),NRG-1β mRNA and protein expression of 4wM group were not exchanged(P0.05).2) Compared with 8wC,LVEF,LVFS,LVESP,± dP/dt max of 4wM were decreased(P0.01),LVEDD,LVESD,LVEDP,CVF and Ang Ⅱwere increased(P0.05,P0.01),NRG-1β mRNA and protein expression of 8wM group were decreased(P 0.01).Conclusions The expression of NRG-1β in myocardium of hypertrophic rats induced by pressure-overloaded is down-regulated,which may be involved in the myocardial hypertrophy development.