Chronic Neuregulin-1β Treatment Mitigates the Progression of Postmyocardial Infarction Heart Failure in the Setting of Type 1 Diabetes Mellitus by Suppressing Myocardial Apoptosis, Fibrosis, and Key Oxidant-Producing Enzymes

Background: Type 1 diabetes mellitus (DM) patients surviving myocardial infarction (MI) have substantially higher cardiovascular morbidity and mortality compared to their nondiabetic counterparts owing to the more frequent development of subsequent heart failure (HF). Neuregulin (NRG)-1 beta is released from cardiac microvascular endothelial cells and acts as a paracrine factor via the ErbB family of tyrosine kinase receptors expressed in cardiac myocytes to regulate cardiac development and stress responses. Because myocardial NRG-1/ErbB signaling has been documented to be impaired during HF associated with type 1 DM, we examined whether enhancement of NRG-1 beta signaling via exogenous administration of recombinant NRG-1p could exert beneficial effects against post-MI HF in the type 1 diabetic heart. Methods and Results: Type 1 DM was induced in male Sprague Dawley rats by a single injection of streptozotocin (STZ) (65 mg/kg). Two weeks after induction of type 1 DM, rats underwent left coronary artery ligation to induce MI. STZ-diabetic rats were treated with saline or NRG-1 beta (100 mu g/kg) twice per week for 7 weeks, starting 2 weeks before experimental MI. Residual left ventricular function was significantly greater in the NRG-1 beta-treated STZ-diabetic MI group compared with the vehicle-treated STZ-diabetic MI group 5 weeks after MI as assessed by high-resolution echocardiography. NRG-1 beta treatment of STZ-diabetic MI rats was associated with reduced myocardial fibrosis and apoptosis as well as decreased gene expression of key oxidant-producing enzymes. Conclusions: These results suggest that recombinant NRG-1 beta may be a promising therapeutic for HF post-MI in the setting of type 1 DM.