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OBJECTIVE To explore the influence of micro ribonucleic acid (miR)-154 on myocardial apoptosis in rats with acute myocardial infarction (AMI), and to analyze whether Wnt/β-catenin signaling pathway was involved in the regulation. MATERIALS AND METHODS The Sprague-Dawley (SD) rat model of AMI was established via ligation of left anterior descending artery. Rats were randomly divided into model group (M group, n=12) and ICG-001 intervention group (I group, n=12). At the same time, sham operation group (S group, n=12) was established. In I group, ICG-001 (5 mg/kg) was intraperitoneally injected every day after operation. Meanwhile, an equal amount of normal saline was injected in rats of S group and M group. 21 d after operation, the cardiac function of rats in each group was detected via echocardiography. After that, the rats were immediately executed. MI area in each group was detected via 2,3,5-triphenyltetrazolium chloride (TTC) staining. Myocardial apoptosis level in each group was detected via terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. Moreover, the changes of apoptotic proteins in rat myocardial cells were detected via Western blotting. Moreover, the expression level of miR-154 in myocardial cells of rats was detected via quantitative polymerase chain reaction (qPCR). Furthermore, the influence of miR-154 on Wnt/β-catenin signaling pathway was detected via Western blotting. RESULTS Compared with S group, left ventricular ejection fraction (LVEF, %) and left ventricular fractional shortening (LVFS, %) were significantly decreased in M group (p<0.01). However, left ventricular internal diameter at end-diastole (LVIDd) and left ventricular internal diameter at end-systole (LVIDs) were significantly increased (p<0.01). In I group, LVEF (%) and LVFS (%) were significantly higher than those of M group (p<0.05), whereas LVIDs and LVIDd were significantly lower (p<0.05). MI area in M group was remarkably larger than that of S group (p<0.01). Meanwhile, MI area in I group was significantly smaller than that of M group (p<0.01). Compared with S group, the number of apoptotic myocardial cells and the protein expression level of cleaved caspase-3 were significantly increased in M group (p<0.01). However, the expression level of B-cell lymphoma-2/Bcl-2 associated X protein (Bcl-2/Bax) was significantly decreased (p<0.01). The number of apoptotic myocardial cells and the protein expression level of cleaved caspase-3 were significantly declined in I group when compared with those of M group (p<0.01). However, the expression level of Bcl-2/Bax was significantly increased in I group (p<0.01). The expression level of miR-154 in myocardial cells of M group and I group was remarkably increased when compared with that of S group (p<0.01). Furthermore, the expression levels of β-catenin and Cyclin D1 in myocardial cells of M group were remarkably higher than those of S group and I group (p<0.01). CONCLUSIONS AMI significantly increases the expression level of miR-154. Moreover, miR-154 can activate Wnt/β-catenin signaling pathway, eventually promoting myocardial apoptosis.