The effect of Aerobic-Resistance Training on the Expression of miR-222 and cTnT, Cx43, Ki67 Genes, and Cardiomyocyte Proliferation in Pre-Pubertal, Young, and Old Male Rats

Background and purpose: The evidence indicates that exercise training can affect the heart's structure at the cellular-molecular levels. Therefore, this study aimed to investigate the effect of exercise training on miR-222 and the expression of cTnT, Cx43 genes, and cardiomyocyte proliferation in pre-pubertal, young adult, and old male rats. Materials and methods: The number of 30 male Wistar rats in three age groups; 2 weeks as the pre-pubertal group, 8 weeks as the young group, and 96 weeks as the old group were randomly divided into two training groups (n=5), and control (n=5). Resistance training programs (resistance ladder, 3 days per week) and aerobic (treadmill running, 3 days per week) were performed for 6 weeks. The expression of miR-222 and Cx43, cTnT, and Ki67 genes were investigated by the Real Time-PCR method. One-way analysis of variance and Tukey's post hoc test were used (P≥0.05). Results: The amount of BrdU protein by immunohistochemical method and Ki67 gene expression was significantly higher in the training groups than in the control groups in all three age groups: pre-pubertal, young adult, and old male rats (P≥0.05). miR-222 was significantly higher in the group of trained pre-pubertal than in the control group (P=0.023). The increase in cTnT gene expression in the pre-pubertal groups (P=0.018) and old rats (P=0.015) and the increase in Cx43 gene expression in the old rats group (P=0.009) was observed. Conclusion: Aerobic-resistance training can be an effective stimulus to increase cardiomyocyte proliferation in all three age groups pre-pubertal, young, and old.