Objective To explore the effect and underlying molecular mechanism of miR-101 on ventricular remod-eling in rats after acute myocardial infarction(AMI).Methods The AMI rat model was established using the left anterior descending coronary artery ligation method.The AMI rats were randomly divided into AMI group,agomir-NC group,miR-101 agomir group and coumermycin A1 group,another 12 rats were selected as sham group with 12 in each.The targeting relationship between miR-101 and JAK2 was analyzed by Target Scan 8.0 database and double luciferase reporter gene assay.The expression of miR-101 in rat myocardium was detected by RT-qPCR.LVESD,LVEDD,LVEF and LVFS were measured by ultrasonography.The level of IL-1β,IL-6 and TNF-α in rats serum was determined by ELISA.The myocardial tissue lesion and fibrosis were detected by HE staining and Mas-son staining.The expression of collagenⅠand TGF-β in rat myocardial tissue was detected by immunohistochemical staining.The expression of E-cadherin,N-cadherin,Vimentin,p-JAK2,JAK2,p-STAT3 and STAT3 proteins was detected by Western blot.Results Compared with AMI group and agomir-NC group,the myocardial tissue lesions and fibrotic area in miR-101 agomir group were significantly decreased(P＜0.05),the level of LVESD,LVEDD,L-1β,IL-6,TNF-α,collagenⅠ,TGF-β,N-cadherin,vimentin,p-JAK2 and p-STAT3 decreased(P＜0.05).The levels of miR-101,LVEF,LVFS and E-cadherin were increased(P＜0.05).Compared with miR-101 agomir group,the myocardial tissue lesions and fibrotic area in coumermycin A1 group significantly increased(P＜0.05),the level of LVESD,LVEDD,L-1β,IL-6,TNF-α,collagenⅠ,TGF-β,N-cadherin,vimentin,p-JAK2 and p-STAT3 was increased(P＜0.05).The level of miR-101,LVEF,LVFS and E-cadherin was decreased(P＜0.05).Conclusions miR-101 inhibits myocardial inflammatory lesions,myocardial fibrosis and epithelial-mesenchymal fransition(EMT)process after AMI with a mechanism targeting at JAK2/STAT3 signaling pathway,thus alleviates ventricular remodeling in rats after AMI.