Sympathetic nerve and vagus nerve remodeling play an important part in cardiac function post-myocardial infarction (MI).Increasing evidence indicates that neuregulin-1 (NRG-1) improves cardiac function following heart failure.Since its impact on cardiac function and neural remodeling post-MI is poorly understood,we aimed to investigate the role of NRG-1 in autonomic nervous system remodeling post-MI.Forty-five Sprague-Dawley rats were equally randomized into three groups:sham (with the left anterior descending coronary artery exposed but without ligation),MI (left anterior descending coronary artery ligation),and MI plus NRG-1 (left anterior descending coronary artery ligation followed by intraperitoneal injection of NRG-1 (10 μg/kg,once daily for 7 days)).At 4 weeks after MI,echocardiography was used to detect the rat cardiac function by measuring the left ventricular end-systolic inner diameter,left ventricular diastolic diameter,left ventricular end-systolic volume,left ventricular end-diastolic volume,left ventricular ejection fraction,and left ventricular fractional shortening.mRNA and protein expression levels of tyrosine hydroxylase,growth associated protein-43 (neuronal specific protein),nerve growth factor,choline acetyltransferase (vagus nerve marker),and vesicular acetylcholine transporter (cardiac vagal nerve fiber marker) in ischemic myocardia were detected by real-time PCR and west blot assay to assess autonomous nervous remodeling.After MI,the rat cardiac function deteriorated significantly,and it was significantly improved after NRG-1 injection.Compared with the MI group,mRNA and protein levels of tyrosine hydroxylase and growth associated protein-43,as well as choline acetyltransferase mRNA level significantly decreased in the MI plus NRG-1 group,while mRNA and protein levels of nerve growth factor and vesicular acetylcholine transporters,as well as choline acetyltransferase protein level slightly decreased.Our results indicate that NRG-1 can improve cardiac function and regulate sympathetic and vagus nerve remodeling post-MI,thus reaching a new balance of the autonomic nervous system to protect the heart from injury.