Background The co-administration of dexrazoxane(DEX)with each dose of doxorubicin(Dox)is an efficient strategy to relieve Dox-induced cardiotoxicity,however,the mechanisms underlying the cardioprotective effect of DEX have not been well elucidated.MicroRNAs(miRNAs)are endogenous,small non-coding RNAs that negatively regulate gene expression in diverse biological and pathological processes.The aim of the present study was to investigate whether the certain cardiac miRNAs were involved in DOX-induced cardiotoxicity.Methods Male SD rats were randomized into five groups,including the 4-week(cumulative dose16 mg / kg)and the 8-week(cumulative dose32 mg / kg)Dox-treated groups,and the corresponding 4-week and 8-week Dox plus DEX-treated groups and the normal control group.Heart functions of the animals were detected by echocardiography.Quantitative real-time PCR was used to determine the expression of cardiac remodeling,apoptosis-related genes and mature micoRNAs of interest.Results The echocardiography detection showed that cardiac remodeling and impaired heart function were observed after 4-week and 8-week Dox treatment,and the cardiac remodeling and decreased ejection fraction(EF%)and fractional shortening(FS%)were efficiently rescued in the corresponding 4-week and 8-week Dox plus DEX-treated groups.The myocardial expression of Anp and CTGF mRNA was significantly upregulated by Dox treatment,but the upregulation of Anp and CTGF mRNA was blocked in the Dox plus DEX-treated groups.IGF-1 mRNA was significantly up-regulated in rat myocardium in Dox plus DEX-treated groups,with no significant changes of Bcl-2 and BAX mRNA expression.Mature miRNAs determination demonstrated that the myocardial miR-1 and -30e were significantly downregulated and miR-21 and -208b were significantly up-regulated in Dox treatment groups,but the above miRNA dysregulation could be efficiently reversed after DEX treatment.Conclusions DEX could tune the microRNAs dysregulation in Dox-treated rat myocardium,miRNAs participated in the cardioprotective activity of DEX against Dox-induced cardiotoxicity. Background The co-administration of dexrazoxane (DEX) with each dose of doxorubicin (Dox) is an efficient strategy to relieve Dox-induced cardiotoxicity, however, the mechanisms underlying the cardioprotective effect of DEX have not been well elucidated. MicroRNAs (miRNAs) are endogenous, small non-coding RNAs that negatively regulate gene expression in diverse biological and pathological processes. The AIM of the present study was to investigate whether the certain cardiac miRNAs were involved in DOX-induced cardiotoxicity. Methods Male SD rats were randomized into five groups , including the 4-week (cumulative dose 16 mg / kg) and the 8-week (cumulative dose 32 mg / kg) Dox-treated groups, and the corresponding 4-week and 8-week Dox plus DEX-treated groups and the normal control group.Heart functions of the animals were detected by echocardiography. Quantitative real-time PCR was used to determine the expression of cardiac remodeling, apoptosis-related genes and mature micoRNAs of interest. Results The Echo cardiography detection showed that cardiac remodeling and impaired heart function were observed after 4-week and 8-week Dox treatment, and the cardiac remodeling and decreased ejection fraction (EF%) and fractional shortening (FS%) were sufficiently rescued in the corresponding 4- week and 8-week Dox plus DEX-treated groups. The myocardial expression of Anp and CTGF mRNA was significantly upregulated by Dox treatment, but the upregulation of Anp and CTGF mRNA was blocked in the Dox plus DEX-treated groups. IGF-1 mRNA was significantly up-regulated in rat myocardium in Dox plus DEX-treated groups, with no significant changes of Bcl-2 and BAX mRNA expression. Legal miRNAs determination of the myocardial miR-1 and-30e were significantly downregulated and miR- 21 and -208b were significantly up-regulated in Dox treatment groups, but the above miRNA dysregulation could could have been reversed after DEX treatment. Conclusions DEX could tune the microRNAs dysregulation in Dox-treated rat myocardium, miRNAs participated in the cardioprotective activity of DEX against Dox-induced cardiotoxicity.