The Effect of Different Exercise Intensities on T-Box Transcription Factor 5 Gene Expression and Hypertrophy in the Heart Muscle of Male Rats

Background: Exercise is one of the methods affecting cardiovascular adaptation, but its cellular and molecular pathways and mechanisms are unknown. T-Box Transcription Factor 5 (TBX5) gene seems to be one of the factors involved in regulating cardiac hypertrophy. Objective: The aim of this study was to investigate the effect of an 8-week exercise program with different intensities on the expression of TBX5 gene in the heart of male Wistar rats. Methods: In this experimental study, 24 male adult Wistar rats were divided into three groups of High Intensity Training (HIT), Low Intensity Training and (LIT) and control. Training groups performed the exercise program for 8 weeks, 5 sessions per week. The exercise program for the HIT group consists of running on a treadmill with five 8-min intervals at 85-90% VO2 max intensity divided into 2-min intervals at 50-60% VO2 max intensity, while for the LIT group it was included five 8-min intervals with 50-60% VO2 max intensity divided into 2-min intervals with 45% -50% VO2 max intensity. The control group performed no exercise. The real-time Polymerase Chain Reaction (PCR) analysis was used to measure the expression level of TBX5 gene. The collected data were analyzed by one-way ANOVA and Tukey’s post hoc test. Findings: The heart weight (P≤0.001 and P=0.004), heart-weight to body-weight ratio (P≤0.0001 and P=0.001), and left ventricular wall thickness were significantly higher in the HIT and LIT groups than in the control group (P≤0.0001 and P=0.38 ). The left ventricular wall thickness in the HIT group was significantly higher than in the LIT group (P=0.001). The TBX5 expression in the two training groups were not significantly different from that of control group (P=0.11). Conclusion: It seems that more intensive exercise can have more significant effects on cardiac hypertrophy than less intensive exercise.