@2024 Afarand., IRAN

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ISSN: 2252-0805    The Horizon of Medical Sciences 2019;25(1):22-28

Background
Elderly is defined by the World Health Organization as passing the age of sixty. In fact, raising people's longevity and increasing aging populations is one of the achievements that many countries have faced. As of today, about 700 million people are aged, and by 2020 this figure will reach more than a billion people [1].
Previous Studies
... [2-4]. According to the American Heart Association in 2009, people over the age of 65 make up 80% of the patients with ischemic heart disease [5]. An explosive increase in cardiovascular mortality rates in the elderly indicates that the elderly heart is an important risk factor for cardiac pathology, including ischemic heart disease [1]. The risk of myocardial infarction increases in old age due to physiological changes that occur. In this regard, animal studies have shown that elderly mice are more susceptible to ischemic-reperfusion myocardial infections compared to young mice [6]. ... [7-11]. Studies have shown that in older rats compared to the younger rates, the level of cardiovascular protection induced by ischemic preeclampsia is reduced [12].
Aim(s)
The purpose of this study was to investigate the effect of high intensive interval training on oxidative stress and myocardial ischemic reperfusion induced myocardial infarction size in elderly rats.
Research type
This is an experimental study.
Research society, place and time
The study population consisted of male Wistar rats in rodent standard laboratory.
Sampling method and number
In this experimental study, 20 male Wistar rats (20 months old) with a weight range of 395 ± 25 grams were used, and no previous research was performed on them, and they were purchased from the Animal Breeding Center of the Faculty of Pharmacology, University of Tehran. Elderly rats were randomly divided into two groups of elderly control and elderly exercise. At all stages of the trial, all ethical considerations regarding working with laboratory animals were considered. Attempts were made to avoid any kind of physical abuse and unnecessary procedures while respecting ethical issues.
Used devices&materials
Elderly exercise group performed high intensity interval training on treadmill (Razi Rad, Iran) for eight weeks, and the control group did not have any activity during this period (Table 1). .. [13]. The training program was run for eight weeks, five sessions a week for the elderly practice group. In the first week, the rats started running at 10 m / min for 10 minutes. The severity and duration of the training increased gradually until the fourth week. Therefore, from the fifth week, the elderly mice performed 10 repetitions of running for two minutes at speeds of 30 to 35 m / min and 12m / min. At the end, the animal ran for 5 minutes with the intensity of 10 meter per minute for cooling [14, 15]. 48 hours after the last training session, animals were first anesthetized with intravenous injection of thiopental sodium (50 mg / kg ip50). The chest region was completely shaved and placed on a surgical bed and 200 U / kg of heparin was injected. The neck of the animal was placed in such a way as to facilitate access to the trachea for intubation. After the intubation, the animal was connected to the Small Animal Ventilator, Harvard Model 683-USA. Then the chest was cut to allow the heart to be exposed. To confirm the ischemia of the mouse, a powerlab device was used to record the electrocardiogram II (HARVARD-USA). Changes in the ST segment were used as an index for confirmation of ischemic production (Fig. 1). To measure the oxidative stress indices after reperfusion, the left ventricle of the myocardium was homogenized at 4 ° C. ... [16]. GPx was measured by the Rundox kit and by the Bradford method in terms of units per milligram of tissue protein (U / mg protein) [17]. Measurement of left ventricular glutathione (GSH) was homogeneous according to the homogeneous solution and, with 0.02% Tris buffer, containing 0.02 EDTA with pH 8.9 and DTNB (0.01M), and absorbance at 412 nm by Sidlock method [18]. Also, the level of catalase (Cat) enzyme in the myocardium tissue was measured based on its ability to decompose H2O2 by American Cayman commercial kit and Aebi method per milligram of protein [19]. Meanwhile, the measurement of Malondialdehyde was performed by the spectrophotometer (DR 6000, HACH, USA) and Ochyama's method in terms of nanomol per milligram of protein [20]. To measure the area of the infarction, at first, 2 ml of Evans Blue solution was injected into the animal's arteries. Immediately, the heart was removed from the animal's body and kept at -70 ° C for 24 hours. Then, they made millimeter cuts of the heart and placed in Triphenylene tetrazolium solution for 20 minutes at 37 ° C, and then the heart cuts were placed in a formaldehyde (10%) for 24 hours., which crossed the cell wall and reaction with intracellular dehydrogenase enzymes in the ischemic tissue (living), caused these areas to become dark red. However, infarction regions could not react with tetrazolium due to necrosis and loss of intracellular dehydrogenase enzymes, which is why these regions became white-yellow (Fig. 2). Finally, using the Photoshop software, the ratio of the infracted left ventricle of the scanned samples was measured as the size of the infarction [21]. Data were analyzed by SPSS software version 20. At first, normal distribution of data was confirmed by Shapiro-wilk test, then independent t-test was used to evaluate the difference between the groups.
Findings by Text
The GPX level in the training group was higher than the control group, but this difference was not significant (p = 0.9; Table 2). The level of GSH in the elderly group was significantly higher than the elderly control group. The GSH level in the control group was 15 ± 1μmol /m g protein, and in the training group, it was 21 ± 1 μmol / mg protein. Also, catalase levels in the elderly group were significantly higher than the control group. In the same way, the results showed that there was no significant difference between the two groups in MDA. On the other hand, 8 weeks of high intensity interval exercises in elderly mice significantly reduced the size of the infarction area after ischemic reperfusion of myocardium.
Main comparison to the similar studies
The findings of this study were in agreement with the findings of Scott et al., who for the first time have shown that aerobic exercise increases the antioxidant capacity of the myocardium after ischemia-reperfusion injury [22]. In line with the findings of this study, Demiril et al. have shown that 10-week aerobic activity has no effect on GPX-induced ischemic-reperfusion injury [23]. By examining the effects of 10 days of running exercise on treadmill for 50 minutes a day in elderly mice, MnSOD increased after reperfusion ischemic injury compared to elderly control mice, but catalase and GPx did not change. The researchers also showed that the amount of left ventricular apoptosis in response to exercise was significantly reduced [24], which was consistent with the results of this study. ... [25]. In line with the findings of this research, Rado et al. (2010) showed that the antioxidant defense system in response to free radicals has different responses [26]. ... [27-33]. Previous studies have shown that elderly rats have a higher level of apoptotic factors, such as Caspase-3, compared to young rats after reperfusion-induced ischemic injury [34]. ... [35].
Suggestions
It is suggested that in subsequent studies, the apoptosis and necroptosis processes of myocardial reperfusion ischemic injury, as well as cardiac function, in response to exercise at an elderly age be considered.
Limitations
One of the most important limitations of this research was the lack of measurement of the indices involved in the apoptosis process, such as Caspase-3, and the non-measurement of functional indicators of the heart.
Conclusions
The 8-week interval training may reduce the size of the infarction area after an ischemic reperfusion of myocardium in elderly mice by increasing the anti-oxidant capacity of GSH.
Acknowledgments
The authorities of Hamadan University of Medical Sciences lab are appreciated for providing the necessary tools for reperfusion ischemic surgery.
Conflict of interest
There is no conflict of interest between the authors.
Ethical Permissions
At all stages of the trial, all ethical considerations regarding working with laboratory animals were considered.
Funding Sources
This article has been extracted from Mr. Adnan Fattahi's thesis and has been done without using the funds of any organization and institution.

TABLES and CHARTS

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