ABSTRACT
AIM:To study the effect of neuregulin-1 ( NRG-1β) or captopril alone and their combination on myocardial cell apoptosis and related gene expression in rats with chronic heart failure .METHODS:Young male Sprague-Dawley rats were randomly divided into sham-operated group, heart failure group, NRG-1βgroup, captopril group and combined treatment group .The volume overloaded heart failure model in the rats was established by aortocaval fistula .The cardiac function was evaluated by determining the changes of hemodynamics and plasma BNP level .The apoptotic index ( AI) of myocardial cells was assayed by TUNEL .The protein levels of p-Akt, Bax and Bcl-2 in left ventricular tissue were detected by Western blot .RESULTS: The LVEDP, AI and the expression of Bax were significantly lower in NRG-1βgroup, captopril group and combined treatment group than those in heart failure group ( P<0.05 ) , while the values of ±dp/dtmax and the protein levels of p-Akt and Bcl-2 were significantly higher in NRG-1βgroup, captopril group and com-bined treatment group than those in heart failure group (P<0.05).The effect of combined treatment group was more signifi-cant ( P<0.05) than that in NRG-1βgroup and captopril group .CONCLUSION: Neuregulin-1βor captopril alone and the combination of them effectively improve the cardiac function and inhibit myocardial cell apoptosis in chronic heart failure rats.The therapeutic effect of combination of NRG-1βand captopril is better than that of NRG-1βor captopril alone .
ABSTRACT
Objective We performed experiments using Neuregulin-1β (NRG-1β) treatment to determine a mechanism for the protective role derived from its beneficial effects by remodeling gap junctions (GJs) during heart failure (HF). Methods Rat models of HF were established by aortocaval fistula. Forty-eight rats were divided randomly into the HF (HF, n = 16), NRG-1β treatment (NRG, n = 16), and sham operation (S, n = 16) group. The rats in the NRG group were administered NRG-1β (10 μg/kg per day) for 7 days via the tail vein, whereas the other groups were injected with the same doses of saline. Twelve weeks after operation, Connexin 43 (Cx43) expression in single myocytes obtained from the left ventricle was determined by immunocytochemistry. Total protein was extracted from frozen left ventricular tissues for immunoblotting assay, and the ultrastructure of myocytes was observed by transmission electron microscopy. Results Compared with the HF group, the cardiac function of rats in the NRG group was markedly improved, irregular distribution and deceased Cx43 expression were relieved. The ultrastructure of myocytes was seriously damaged in HF rats, and NRG-1β reduced these pathological damages. Conclusions Short-term NRG-1β treatment can rescue pump failure in experimental models of volume overload-induced HF, which is related to the recovery of GJs structure and the improvement of Cx43 expression.