Volume 28, Issue 10 (12-2021)                   RJMS 2021, 28(10): 1-11 | Back to browse issues page

Research code: با تایید دانشگاه علوم پزشکی بقیه ا... (عج)
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Rahimi M, Nowroozi M, Asad M R, hemati farsani Z. Effects of 8-week Interval and Continuous Training on Brain-Derived Neurotrophic (BDNF) and Insulin-like Growth-1 (IGF-1) in Wistar Male Rat. RJMS 2021; 28 (10) :1-11
URL: http://rjms.iums.ac.ir/article-1-6345-en.html
Assistant professor, Department of Sport Sciences, Faculty of Education and Psychology, Ardakan University, Ardakan, Iran , hematyn.sport87@yahoo.com
Abstract:   (1339 Views)
Background & Aims: Physical activity is associated with a range of positive health outcomes, including fewer depressive symptoms. One plausible mechanism underlying these findings involves Brain-Derived Neurotrophic Factor (BDNF) (1), a protein hypothesized to limit or repair the damage caused by stress. Physical activity increases expression of BDNF, which may enhance brain health (1). In addition, insulin-like growth factor (IGF1) is involved in neurogenesis and regulation of the BDNF gene, and is involved in the growth and differentiation of nerve cells (4). Therefore, one of the factors that may mediate the effects of physical activity and BDNF in the brain is IGF1. Physical activity can stimulate the production of IGF1 by increasing circulating growth hormone. This factor has different biological effects such as neurogenesis, memory effects and cognitive factors and other systemic effects (3). Therefore, it has been suggested that the increase in IGF1 due to physical activity leads to an increase in BDNF, thus increasing the amount of hippocampal synaptic flexibility and expression of molecules related to learning and cognitive functions with physical activity (4).
Studies on peripheral blood have been contradictory, with some studies reporting that BDNF increased after physical activity, others decreased, and some showed no significant change (14). On the other hand, afew study was found to measure the effect of intermittent and continuous exercise on serum IGF1 and BDNF levels. Therefore, in this study, we seek to answer the question of whether intense or intermittent intermittent exercise causes serum changes in IGF1 and BDNF in mice, and which exercise method can further influence these two factors.
Methods: This was an experimental study with a control group. The samples were 32 eight-week-old male Wistar rats. rats were randomly divided into 4 groups, as follows: moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT), and the baseline control group (C) and the eight weeks control group (C8w). Group C was killed and serum harvested at baseline, and group C8w was retained for eight weeks at the same time as the exercise groups, but did not participate in any exercise program.
The MICT group trained for 5 days a week for 8 weeks. The method was according to the training program (13). These exercises were performed for eight weeks and five sessions of running on a treadmill every week (14). BDNF and IGF-1 concentration was measured using an ELISA kit (BASTER kits made in the United States). Normal distribution of data was examined by the Shapiro-Wilk test. To examine the possible difference between groups, 1-way Analysis of Variance (ANOVA) and Tukey post hoc test were performed in SPSS. The significance level was set at P ≤ 0.05.
Results: The results of statistical test showed that the amount of serum IGF-1 levels after MICT training significantly decreased compared to groups C (P = 0.00) and C8w (P = 0.00). Also, a significant decrease in this protein was observed after HIIT training compared to groups C (P = 0.03) and C8w (P = 0.01), but no significant difference was observed between the two groups of HIIT and MICT training. Regarding BDNF variable, protein levels after MICT and HIIT training did not change compared to group C (P = 0.99 and P = 0.91) and C8w group (P = 0.99 and P = 0.98), respectively. There was also no significant difference in serum levels of BDNF protein after MICT and HIIT (P = 0.99).
Conclusion: One of the findings of the present study was the change in BDNF blood circulation levels after exercise intervention, although this change was not statistically significant, but the smallest change in blood circulation levels of this nerve growth factor is clinically important. Because BDNF is one of the main modulators of brain adaptation. These results are similar to the findings of the research of Ives et al. (2016) and Abbaspoor et al. (2020) and with the results of studies by Kallies et al. (2019), Máderová et al. (2019), Church et al. (2016), Kang et al. (2020), Akbari-Fakhrabadi et al. (2021) and Żebrowska et al. (2020) disagree (18-25).
one of the reasons for the lack of change in BDNF levels is the intensity and duration of exercise that affects each individual, so that in rodents, an increase in hippocampal BDNF occurs when mice Voluntarily ran about 3,000-10,000 meters a day on a treadmill. In addition to methodological issues, serum BDNF levels may vary due to circadian rhythms of cortisol or sex-dependent hormonal fluctuations and energy balance and nutritional variables (27). Therefore, future studies should consider the period of assessment of exercise-induced flexibility by evaluating short-term and long-term measures of growth factors, perfusion, volume, and memory.
Another finding of the present study was a significant change in serum IGF-1 levels after two exercise interventions.This means that a significant decrease in the levels of this growth factor was observed after MICT and HIIT training compared to the control groups. Changes in growth factors and adaptations in response to exercise can affect the type, intensity, duration, and frequency of exercise sessions. The present results are in agreement with the findings of Yalanda et al. (2019), Valipour et al. (2019), Ives et al. (2016), Żebrowska et al. (2020) and with the findings of Maass et al. (2016) and Johnson et al. (2020) is the opposite (18, 25, 27, 34-36)
A number of researchers have suggested that aerobic exercise stimulates the uptake of IGF-1 nerve growth factor into the bloodstream by cells in specific areas of the brain, such as the hippocampus (35, 37, 38). On the other hand, the type of exercise is very important in response to systemic growth factors such as IGF1 blood levels (39). Whether the increase in IGF1 blood levels is due to a decrease in IGF1 uptake from the bloodstream by the brain or a double increase in the production of this hormone from major sources of its production, such as the liver, is still unclear and needs further study.
However, since the present study did not investigate the expression of genes and tissue levels as well as changes in IGF1 receptors at the cellular level, These cases cannot be strongly cited in explaining the results and further studies are needed to elucidate the exact mechanisms of changes in this growth factor by simultaneously measuring gene expression, protein levels, and IGF1 receptors with exercise.
In general, it can be concluded that intermittent and continuous exercise significantly decreased IGF1 and also caused a non-significant increase in serum BDNF in male Wistar mice. Exercise as a physiological stress can play a vital role in the normal functioning of the brain by changing the growth factors of the environment and blood circulation. According to the available evidence on the ability of systemic IGF1 to cross the blood-brain barrier, small changes in the levels of this growth factor with exercise can be considered in the physiological adaptations of the brain to exercise. One of the limitations of the present study is the lack of study on the expression of BDNF gene in brain tissue. Also, recent studies show that brain health can be affected by physical activity and exercise. Therefore, it seems necessary to study sports interventions with different type, volume and duration of the present study on brain function and structure, as well as simultaneous examination of tissue and systemic levels of growth factors.
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Type of Study: Research | Subject: Exercise Physiology

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