| Objective To investigate the changes of ventricular myocardial pri-miRNA-1, dicer1 mRNA and connexin43 (Cx43) in murine model of viral myocarditis (VMC) induced by coxsackievirusB (CVB), and to elucidate the relationgship of microRNAs-1(miRNA-1) and Cx43 in VMC and the significance of these changes.Methods one hundred and forty four-week-old male Balb/c mice were divided randomly into VMC group (n=80) and control group (n=60). Mice in VMC group were further divided into four subgroups: 7 day (n=20), 14 day (n=20), 28 day (n=20) and 42 day (n=20). Mice in control group were assigned similarly (n=15). Myocarditis model was founded by injecting intraperitoneally 0.1 ml CVB3 Nancy suspension. Control mice were injected with 0.1 ml RPMI 1640 excluding virus. The levels of ventricular myocardial pri-miRNA-1,dicer1 mRNA and Cx43 mRNA were measured by RT-PCR. Cx43 proteins in ventricular myocardium were determined by immunohistochemistry. Results 1.Compared with control group, the levels of ventricular myocardial pri-miRNA-1 and dicer1 mRNA significantly increased in viral myocarditis group(P﹤0.01); The peak levels of pri-miRNA-1 and dicer1 mRNA were showed on day 14; 2. The levels of Cx43 mRNA and protein were decreased remarkably in viral myocarditis group(P﹤0.01). The decreased expressions of Cx43 was located in the zone of myocardium which was degenerative or necrosis. The distribution of Cx43 protein was inordinated; 3. ventricular Myocardial pri-miRNA-1 was positively correlated with dicer1 mRNA(r=0.462, P﹤0.01), negatively correlated with Cx43 mRNA (r=-0.360, P﹤0.01) and Cx43 protein(r=-0.257, P﹤0.05).Conclusion The levels of pri-miRNA-1 and dicer1 mRNA were increased obviously in murine myocarditis induced by CVB while Cx43 protein was decreased remarkably. MiRNA-1 might play an important role in the process of viral myocarditis and might inhibit the expressions of Cx43 protein.
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