The Changes of Heart miR-1 and miR-133 Expressions following Physiological Hypertrophy Due to Endurance Training

OBJECTIVE: MicroRNAs (miRNAs) play a key role in the development of the heart. Recent studies have shown that miR- 1 and miR-133 are key regulators of cardiac hypertrophy. Therefore, we aimed to evaluate the effect of an endurance training (ET) program on the expressions of these miRNAs and their transcriptional network. MATERIALS AND METHODS: In this experimental study, cardiac hypertrophy was induced by 14 weeks of ET for 1 hour per day, 6 days per week at 75% VO2 max). The rats (221 ± 23 g) in the experimental (n=7) and control (n=7) groups were anesthetized to evaluate heart morphology changes by echocardiography. Next, we evaluated expressions of miR-1 and miR-133, and heart and neural crest derivatives express 2 (Hand2), Mef2c, histone deacetylase 4 (Hdac4) and serum response factor (Srf) gene expressions by real-time polymerase chain reaction (PCR). Finally, the collected data were evaluated by the independent t test to determine differences between the groups RESULTS: The echocardiography result confirmed physiological hypertrophy in the experimental group that underwent ET as shown by the increased left ventricular weight/body surface area (LVW/BSA) (P=0.004), LVW/body weight (BW) (P=0.011), left ventricular diameter end-diastolic (LVDd) (P=0.003), and improvements in heart functional indexes such as fractional shortness (FS) (P=0.036) and stroke volume (SV) (P=0.002). There were significant increases in the expressions of miR-1 (P=0.001) and miR-133 (P=0.004). The expressions of Srf, Hdac4, and Hand2 genes significantly increased (P<0.001) in the experimental group Compared with the control group. The expression of Mef2c did not significantly change. CONCLUSION: The expressions of miR-1 and miR-133 and their target genes appeared to be involved in physiological hypertrophy induced by ET in these rats.