Volume 29, Issue 5 (8-2022)                   RJMS 2022, 29(5): 31-40 | Back to browse issues page

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Rakhshanizade A, Banaeifar A, Hajrasouli M, Arshadi S. The Effect of A Resistance Training Course on Drp1 Level in Heart Tissue of Obese Rats with Type 2 Diabetes. RJMS 2022; 29 (5) :31-40
URL: http://rjms.iums.ac.ir/article-1-6020-en.html
Associate Professor, Department of Exercise Physiology, Faculty of Human Sciences, Islamic Azad University, South Tehran Branch, Tehran, Iran , alibanaeifar@yahoo.com
Abstract:   (1345 Views)
Background & Aims: Diabetes is the most common cause of renal diseases, new cases of blindness, and non-traumatic amputation. Prevalence of cardiovascular diseases among Type 2 diabetic patients is four times more than other individuals of a society (4). Diabetic cardiomyopathy is the deterioration of performance and morphology of myocardium which results from disturbances of glucose hemostasis in the diabetic condition and occurs independently from coronary disease. In the cell level, diabetic cardiomyopathy is characterized by hypertrophy of the heart cells, fibrosis, and apoptosis (5). Shortage of energy in the heart muscle is related to the commencement and development of different heart diseases including the conditions observed during insulin resistance and type-2 diabetes (6). In the condition of insulin resistance, the power of heart muscle declines to use glucose as the source of energy. This change in the preferred substrate has a vital role in the pathogenesis of diabetic cardiomyopathy (7). Mitochondria are highly congested in the heart and occupy 30 percent of heart cells, and produce over 90 percent of intracellular ATP which is consumed by heart (8). Therefore, many studies, nowadays, have focused on the mitochondrial function disorder as a causative factor for metabolic disorders and heart diseases which are connected with insulin resistance.  Mitochondria are dynamic organelles which continuously change their morphology in response to intercellular conditions through fusion and fission, and a change in the balance of these processes affects different biological events including cell division, apoptosis, autophagy, and metabolism (9). Mitochondrial fission is mainly controlled by the protein which is connected to cytoplasmic dynamin GTPases 1 (Drp1) (10).   To the best knowledge of the researchers of the present study, there are few studies which particularly show the direct relationship between cardiac mitochondria fission, insulin resistance and diabetes type 2. However, it is well known that the main contributor which triggers diabetic cardiomyopathy is the oxidative stress resulted from hyperglycemia (11). Makino et al. in a different but related model showed that mitochondria fragmentation in the cardiac endothelial cells which were obtained from the heart of diabetic rats resulted in an increase in the level of Drp 1 (15). Sports and exercises are prescribed as a part of therapeutic methods for heart disease patients since these activities decrease heart risk factors, protect myocardium and improve heart performance (18). Exercises are also suggested as a non-medicinal therapy for type 2 diabetic patients because they have numerous benefits including improvement of insulin sensitivity and weight loss (19-21). The present experimental study was designed aiming to investigate the effect of one course of resistance training on the fasting levels of blood glucose and insulin also Drp1 in the cardiac tissue of type-2 diabetic obese rats. 
Methods: In order to conduct the present study, initially 14 Wistar male rats with an average age of 10 weeks and average weight 220 ± 20 were obtained from Pasteur Institute of Iran. The rats were then randomly divided into two groups of control (7 rats) and resistance training (7 rats). To induce diabetes type 2, the rats were initially fed a high-fat diet. After the rats reached the required weight, they were made diabetic by intraperitoneal injection of STZ (25 ml / per kg of weight).  Resistance training protocol: the rats in the resistance training group participated in an 8-week resistance training program (5 sessions a week) starting at the 18th week. Each session included 5 sets; and each set consisted of 4 repetitions of carrying a weight through the ladder with rest intervals of 2 minutes between sets and 30 seconds between repetitions. The applied exercise load was as follow:
First week: 30 percent of the body weight, Second week: 40 percent of the body weight, Third week: 50 percent of the body weight, Fourth week: 60 percent of the body weight, Fifth week: 70 percent of the body weight, Sixth week: 80 percent of the body weight, Seventh week: 90 percent of the body weight, Eighth week: 100 percent of the body weight (24).
All the animals were anesthetized by the intraperitoneal injection of mixture of Ketamine 10% with the dose of 50 mg per kg of weight and Xylazine 2% with the dose of 10 mg per kg of weight. The rats were anesthetized 48 hours after the last training session and in a nocturnal fasting status. After the anesthetization was fully done, the chest of the animal was incised using a scalpel and blood samples were directly collected from the heart of the animal. It should be mentioned that all steps of the present research were conducted based on the by-law of “Research Ethics Committee of Islamic Azad University” with the ethical code of IR.SSRC.REC.1398.043.
The Drp1 gene expression level was measured using Real time – PCR. The software of SPSS 16 was employed for data analysis. Kolmogorov- Smirnov test was used to examine the normality of data distribution.  Independent T-test was employed to examine the difference between the groups. p≤0.05 was considered significant.
Results: The results of the present study showed that resistance training caused a reduction in the blood glucose level of the rats in the experimental group compared to the diabetic control group rats (p≤0.001). Blood insulin level in the trained diabetic rats was significantly higher compared to the rats in the control diabetic group(p≤0.01). Expression of the Drp 1 gene was significant lower in the experimental trained rats compared to the rats of the control diabetic group (p≤0.001). Generally, the results of the present study revealed that one course of resistance training can decrease blood glucose level by improving lowered insulin levels. Also, resistance training can lead to a balance in the biogenesis by negative regulation of mitochondrial over-fission.
Conclusion: According to the findings of the study, diabetic patients are recommended to take resistance training under the supervision of the physician to reduce obesity and diabetes complications.

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Type of Study: Research | Subject: Exercise Physiology

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