Document Type : Research Paper
Authors
1
PhD Student in Exercise Physiology, Faculty of Sport and Health Sciences, Shahid Beheshti University, Tehran, Iran
2
Professor in Exercise Physiology, Faculty of Sport and Health Sciences, Shahid Beheshti University, Tehran, Iran
3
Assistant Professor in Exercise Physiology, Faculty of Sport and Health Sciences, Shahid Beheshti University, Tehran, Iran
4
Professor in Exercise Physiology, Department of Circulation and Medical Imaging, Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
Abstract
Background and Purpose
Recently, aging has become one of the major health challenges. Unfortunately, physiological changes during aging lead to a decrease in the quality of life and an increase in the mortality rate in elderly people. Although it is impossible to stop these changes, numerous studies have shown that many factors, including exercise and physical activity, can improve the quality of life and cardiovascular function in elderly people. One of the important factors affected by exercise is the expression of cardiac genes in different tissue like as myocardium, SA node, and AV node. Two important cardiac anti-aging genes that have recently attracted the attention of researchers are AKT1 and GATA4. Many studies have shown that moderate and high-intensity aerobic exercise can cause significant changes in cellular and molecular signals upstream of AKT1 and GATA4 expression in cardiac tissue. Therefore, the aim of this study was to investigate the effect of various types of exercise on the expression of anti-aging genes in myocardial tissue, SA node, and AV node in elderly rats.
Materials and Methods
Twenty-four male Wistar rats aged 23 months with a body mass between 420 and 510 g were recruited in this study. Prior to the study, all rats were familiarized with the pool and swimming at a shallow depth. Familiarization involved placing the rats in shallow water at 32°C for 10 minutes per day for three consecutive days. Therefore, the maximal load for each rat was measured. To calculate and determine the maximal workload for all rats, a metal weight equal to 5% of their body weight was attached to their tails with leukoplast tape. After 5 min swimming was 1g added to the workload and continued swimming till exhaustion. The highest amount of weight that rats able to swim with was considered as maximal workload. After determining the maximum workload, the rats were randomly assigned to 4 equal groups (n=6): control, continuous exercise, high intensity interval exercise (HIIE-HV), and low intensity interval exercise (HIIE-LV). The continuous exercise consisted of 35 min swimming at 65% maximal workload. The HIIE-HV consisted of 35 min interval swimming encompassed 5 sets of 4 min swimming at 85% maximal workload and 3 min of passive recovery. The HIIE-LV consisted of 7 min interval swimming encompassed 14 sets of 30 s swimming at 110 % maximal workload interspersed by 30 s of passive recovery. After exercise, all rats were dried gently with towel and anesthetized with ketamine and xylazine. After extraction of their hearts, all tissues were placed in a nitrogen tank and transferred to the laboratory. To determine the gene expression levels of GATA4 and AKT1 in the left ventricular myocardium tissue, SA node, and AV node, reverse transcription polymerase chain reaction (RT-PCR) or quantitative real time polymerase chain reaction (qRT-PCR) was performed. To analyze the research findings, to determine the normality of the data the Shapiro-Wilk test were used. To compare of means between different groups, ANOVA one-way analysis of variance with Tukey’s post- hoc test were used (p < 0.05).
Results
Data analysis of the present study showed that HIIE-HV exercise significantly increased the expression of GATA4 and AKT1 genes in the left ventricular myocardial tissue, SA node, and AV node compared to the control group and other exercise groups. While HIIE-LV exercise significantly increased the expression of GATA4 and AKT1 genes in the left ventricular myocardial tissue and SA node compared to the control group (P<0.05), and there was no change in the level of AKT1 and GATA4 expression in AV node compare than control group (P<0.05). Althought, the results of post-hoc test showed that there was a significant change in AKT1 and GATA4 expression between HIIE-HV, HIIE-LV, and continuous exercise (P<0.05). In addition, there were significant changes in expression of AKT1 and GATA4 between HIIE-HV, HIIE-LV, and continuous groups in the left ventricular myocardium tissue, SA node, and AV node (P<0.05).
Conclusion
Based on the findings of the present study, it seems that high intensity interval exercise with low and high volume can activate anti-aging genes in myocardial tissues, SA and AV node in elderly rats. Although, the level of AKT1 and GATA4 expression in myocardial tissues, SA and AV node in response to continuous exercise at moderate intensity compare to control group were not significant changed but the level of these anti-aging genes were higher than control group. It seem that aerobic exercise with any type and intebsity can promote cardiac function. Previous studies have suggested that various molecular cellular signals are involved in the expression of anti-cardiac aging genes. Interestingly, exercise can increase the expression of these cardiac anti-aging genes by activating signals related to cellular metabolism, stress, and mechanical factors such as cell wall stretch.
Article Message
Recent studies have highlighted the effect of different exercise protocols on gene expression related to anti-ageing in the hearts of elderly rats. This study demonstrated that high intensity interval exercise with high volume can increase significantly the level of GATA4 and AKT1 in the left ventricular myocardium, SA node, and AV node of elderly rats.
Ethical Considerations
The animal study protocol was approved by the Ethics Committee of Shahid Beheshti University. Ethics Code: IR.SBU.REC.1403.134
Authors’ Contributions
All authors contributed to the design, implementation, and writing of all parts of the present study.
Conflict of Interest
The authors declare no conflict of interest.
Acknowledgments
We thank all those who helped us in this study. This study received no funding from public, commercial, or nonprofit organizations.
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