Background:Matrix metalloproteinase (MMP)-2 plays an important role in the remodeling of left ventricles (LVs) and right ventricles (RVs).We investigated the differences of MMP-2 expression between LV and RV in response to nandrolone decanoate (ND),swimming training (ST),and combined ND and ST (NS) in mice,based on their structural,functional,and biochemical characteristics.Methods:Totally 28 male C57B1 mice (6 weeks old;20-23 g) were divided into four groups,including the control (n =7),ND (n =6),ST (n =8),and NS (n =7) groups.After respective treatments for 8 weeks,echocardiographic examination was used to assess the cardiac structure and function.Van Gieson stain was used to examine the fibrosis of LV and RV in response to different treatments,and West blotting analysis was performed to explore different MMP-2 expressions between LV and RV in response to ND and/or ST.Analysis of variance was used for comparing the four groups.Results:At 8 weeks,right ventricular dimension/body weight in the ND group was larger than the other three groups (F =7.12,P ＜ 0.05)according to the echocardiographic examination.Fibrosis induced by ND administration was increased more in RV (2.59％) than that in LV (2.21％).MMP-2 expression of the ND group in RV was significantly greater than the control and NS groups in RV and the corresponding ND group in LV.Conclusion:The experimental data support the hypothesis that ND administration induces greater MMP-2 expression increase in RV compared to LV,leading to consequent RV dilation.