Swimming training affects apoptosis-related microRNAs and reduces cardiac apoptosis in mice.

We sought to investigate effects of exercise training on apoptosis-related microRNAs (miRs) and their validated targets, discussing molecular mechanism of the exercise-induced benefit in heart. Male C57BL/6 mice were randomly assigned to three groups: sedentary (SE), exercise training 1 (ET1) and exercise training 2 (ET2). ET1 swam for 8 weeks, once a day and 5 days per week with incremental load. ET2 performed the same work as ET1 and switched to twice a day by the end of the 5th week. In ET2, positive cell rate (%) tested by TUNEL assay decreased significantly (p < 0.05), and the load decreased miR-1 level by 29% (p < 0.01), also increased miR-30b and miR-21 levels by 32% (p < 0.01) and 18% (p < 0.05) respectively. In addition, Bcl-2 expression was increased by 98% (p < 0.01). p53, PDCD4 and Drp-1 expressions were decreased by 45% (p < 0.01), 6% (p > 0.05) and 36% (p < 0.01) respectively, compared with SE. In ET1, only miR-30b level was increased by 22% (p < 0.05) with a 48% decrease in p53 level (p < 0.01). Both swimming groups increased Bcl-2/Bax ratio significantly (p < 0.01). This study indicated that apoptosis-related miRs and their downstream proteins in heart can be influenced by swimming training that may be responsible for the exercise-induced cardioprotection.