vbmoron@gmail.com

linebmachado@hotmail.com

samynh@hotmail.com

kalinkarigo@hotmail.com

micaelaconstante.19@gmail.com

cassiac@feevale.br

magdaperassolo@feevale.br

danielaosorio@feevale.br

sanfeliceg@feevale.br

daianeb@feevale.br

*Master degree in Environmental Quality at University Feevale

Graduated in Physical Education at UNISINOS

** PhD student in Environmental Quality Post Graduation Program at University Feevale

Master degree in Environmental Quality at University Feevale

Graduated in Biomedicine at University Feevale

*** Master degree in Environmental Quality at University Feevale

Graduated in nursing at University Feevale

****Nutrition student at Feevale University and undergraduate student

in scientific research in Environmental Quality Research Group at Feevale University.

*****Nursing student at Feevale University

Infection Control intern at Hospital Centenário in São Leopoldo

Received a scientific research scholarship for two years from

the Environmental Quality Research Group and an internship in Infection Control

at Hospital Unimed Vale do Sinos in Novo Hamburgo

****** Professor at University Feevale

PhD in Pneumological Sciences at Federal University of Rio Grande do Sul

Master in Production Engineering at Federal University of Rio Grande do Sul

Graduate in Physiotherapy at University Feevale

*******Professor at University Feevale

PhD in Medical Sciences: Endocrinology at Federal University of Rio Grande do Sul

Master degree in Medical Sciences: Endocrinology

at Federal University of Rio Grande do Sul

Graduated in Pharmacy at Federal University of Rio Grande do Sul

********Professor at University Feevale

PhD in Ecology at Federal University of Rio Grande do Sul

Master degree in Electrical Engineering at PUCRS

Graduated in Chemistry at PUCRS

*********Professor at University Feevale

PhD in Communication Sciences at UNISINOS

Master degree in Human Movement Science at Federal University of Santa Maria

Graduate in Physical Education at Federal University of Santa Maria

********** Professor at University Feevale

PhD in Toxicological Biochemistry at Federal University of Santa Maria

Graduate in Chemistry at Federal University of Santa Maria

(Brazil)

Reception: 08/09/2019 - Acceptance: 06/03/2020

1st Review: 05/19/2020 - 2nd Review: 06/01/2020

Accessible document. Law N° 26.653. WCAG 2.0

Suggested reference: Moron, V.B., Machado, A.B., Moraes, S.C.S. de, Rigo, K.A., Constante, M. da S., Costa, C.C. da, Perassolo, M.S., Osório, D.M.M., Sanfelice, G.R., & Berlese, D.B. (2020). Protective effect of aerobic physical training on oxidative stress caused by particulate matter in rats. Lecturas: Educación Física y Deportes, 25(270), 128-141. Retrieved from: https://doi.org/10.46642/efd.v25i270.1543

 

Abstract

    Introduction: Particulate matter (PM) is an atmospheric pollutant associated with many deleterious health effects. Oxidative stress is among these effects, that can result from a local inflammatory response to systemic damage to the organism. Studies indicate that when an individual is submitted to aerobic physical training, it generates an antioxidant protective effect that overcomes the damages caused by PM. Objective: Therefore, the aim of this study was to evaluate the influence of the particulate matter PM_2.5 and PM₁₀ on the oxidative stress parameters. Methods: The evaluation of the influence of PM on oxidative stress parameters was performed by the dosages of superoxide dismutase, catalase, glutathione peroxidase, and total antioxidant power in male Wistar rats not exposed to the particulate matter, with and without aerobic physical training, and exposed to PM_2.5 and PM₁₀, with and without aerobic physical training. This protocol lasted five weeks. Results: The antioxidant enzymes analyzed that presented significant differences were catalase, and glutathione peroxidase. Conclusions: From this research, it was possible to perceive that PM influences negatively on the oxidative stress and in the weight of the rats and that the aerobic exercise generates a protective effect against these damages.

    Keywords: Energy metabolism. Oxidative stress. Particulate matter. Exercice.

 

Resumen

    Introducción: El material particulado (MP) es un contaminante del aire asociado con efectos nocivos para la salud. Estos efectos incluyen el estrés oxidativo, que puede ser el resultado de una respuesta inflamatoria local al daño sistémico del cuerpo. Algunos estudios indican que cuando el individuo se somete a in entrenamiento físico aeróbico, genera un efecto protector antioxidante que supera los efectos nocivos generados por el MP. Objetivo: Por lo tanto, el objetivo del estudio fue evaluar la influencia de las partículas MP_2.5 y MP₁₀ sobre el estrés oxidativo. Métodos: La evaluación de la influencia de la MP en los parámetros de estrés oxidativo se llevó a cabo utilizando superóxido dismutasa, catalasa, glutatión peroxidasa y niveles de antioxidantes totales en ratas Wistar machos no expuestas a partículas, con y sin entrenamiento aeróbico y expuesto a partículas MP_2.5 y MP₁₀, con y sin entrenamiento aeróbico. Resultados: Las enzimas antioxidantes analizadas que mostraron una diferencia significativa fueron catalasa y glutatión peroxidasa. Conclusiones: De esta investigación fue posible darse cuenta de que la MP influye negativamente en el estrés oxidativo y el peso corporal de las ratas y que el ejercicio aeróbico genera un efecto protector contra estos daños.

    Palabras clave: Metabolismo energético. Estrés oxidativo. Material particulado. Ejercicio físico.

 

Resumo

    Introdução: O material particulado (MP) é um poluente atmosférico associado a efeitos deletérios à saúde. Dentre estes efeitos, está o estresse oxidativo, que pode resultar desde uma resposta inflamatória local até danos sistêmicos ao organismo. Alguns estudos apontam que quando o indivíduo é submetido a treinamento físico aeróbico, gera efeito protetor antioxidante que supera os malefícios gerados pelo MP. Objetivo: Assim, o objetivo do estudo visou avaliar a influência do material particulado MP_2.5 e MP₁₀ no estresse oxidativo. Métodos: A avaliação da influência do MP nos parâmetros do estresse oxidativo foram realizados através de dosagens de superóxido dismutase, catalase, glutationa peroxidase e poder antioxidante total em ratos Wistar machos não expostos ao material particulado, com e sem treinamento físico aeróbico e expostos ao material particulado MP_2.5 e MP₁₀, com e sem treinamento físico aeróbico. Este protocolo teve a duração de cinco semanas. Resultados: As enzimas antioxidantes analisadas que apresentaram uma diferença significativa foram a catalase e a glutationa peroxidase. Conclusões: A partir desta pesquisa foi possível perceber que o MP influência negativamente no estresse oxidativo e no peso corporal dos ratos e que o exercício aeróbico gera efeito protetor contra estes danos.

    Unitermos: Metabolismo energético. Estresse oxidativo. Material particulado. Exercício físico.

 

Lecturas: Educación Física y Deportes, Vol. 25, Núm. 270, Nov. (2020)

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Introduction 

 

The rapid advancement in technology in recent times brought along an increase of pollutants released into the atmosphere, damaging the quality of life on our planet (Castro et al., 2003). Atmospheric pollution is associated with the imbalance and deterioration of air quality (Dallarosa et al., 2008), and it is defined as the presence of a mixture of substances resulting from natural processes or from anthropogenic activities, in sufficient concentrations to affect the health, safety, and well-being of living organisms. (Cançado et al., 2006)

 

    The atmospheric pollutants (AP) and the particulate matter (PM) generate a huge impact on human health (WHO Europe, 2013), mainly in big cities, where elevated number of people are near polluting sources, such as industries and traffic (Samet, & Gruskin, 2015). The PM contained in the atmosphere is composed of solid and liquid particles of various granulometries, shapes, and chemical composition, which depends on their source and origin. The PM can be of a primary origin, emitted by natural sources directly into the atmosphere, or secondary origin, emitted by anthropogenic sources, that is, derived from human activities (Arbex et al., 2012). Pollutantsare classified according to their aerodynamic size in inhalable or coarse particles; (PM₁₀) when the diameter is smaller than 10 µm and bigger than 2.5µm, and fine particles (PM_2.5) up to 2.5 µm (Braga et al., 2001). The PM with a larger diameter is retained in the upper airways, while the PM with smaller diameter reaches the alveolus. (Cançado et al., 2006)

 

    Inhalation of particulate matter is associated with the emergence of several deleterious health effects (Pearson et al., 2010; Yuan et al., 2016). Particles can be toxic and cause the induction of oxidative stress, initiating an inflammatory response that reaches the systemic circulation, leading to inflammation with repercussion not only in the respiratory system but causing systemic effects. (Grochanke, 2015; Wong et al., 2016)

 

    After the inhalation of particulate matter, the pulmonary cells release pro-inflammatory mediators and vasoactive molecules, by which exposure to these particles can induce various processes including the increase of reactive oxygen species (ROS) and nitrogen (RNS), thus triggering an increase of the oxidative stress. Oxidative stress can induce cellular apoptosis in the lungs and induce the pulmonary inflammatory process. The systemic inflammatory response occurs through the release of pro-inflammatory mediators, such as, cytokines, leukocytes, and platelets released by the lungs. (Huttunen et al., 2012; Martinelli et al., 2013)

 

    A second proposed process involves the imbalance of the autonomic nervous system, triggered by the interaction of environmental particles that were inhaled with the pulmonary neural receptors. This mechanism is also associated with an increase of the heart rate, triggering cardiac arrhythmias that may progress to congestive heart failure (Rhoden et al., 2004). Another possible mechanism consists of the direct translocation of the PM through the blood flow, providing interaction with the endothelial cells and platelets, causing deleterious effects in the vasculature and hemostasis. (Sorensen et al., 2003; Brook, 2008; Martinelli et al., 2013)

 

    Antioxidants are agents responsible for the inhibition or reduction of these effects on health, and act at several levels of defense on our organism. Under normal circumstances of homeostasis, usually the tissue antioxidant enzymes are sufficient to regulate the oxidative activity (Vollaard et al., 2005), however, in some situations, such as the practice of physical exercise, an increase in oxygen consumption in the cells occurs, which is directly proportional to the generation of oxidative stress. (Banerjee et al., 2003)

 

    In addition, some studies indicate that the generation of reactive oxygen species is increased when individuals regularly perform an aerobic exercise (training) in environments with atmospheric pollution, due to the amplification of minute ventilation (MV); pulmonary deposition; and toxicity of inhaled pollutants. (Strak et al., 2010)

 

    Besides the increase in inhalable particles, physical exercise is also related to the oxidative stress in two manners: on the one hand it is capable of increasing the oxidative metabolism which generates the greater formation of free radicals, and on the other hand it is capable of producing an antioxidant protective effect, promoted by regular sessions (training) (Coelho et al., 2010; Silva et al., 2010; Fashi et al., 2015). Therefore, the aim of this research was to evaluate the particulate matter PM_2.5 and PM₁₀ on oxidative stress in male Wistar rats with and without aerobic physical training.

 

Methods 

 

Collection and analysis 

 

    Particulate matter samples were collected in the metropolitan area of Porto Alegre. The sample collection occurred at least once a month at each site of collection over the period of one year. The atmospheric particles, fine and coarse, were collected utilizing a fine and coarse matter sampler (FCS), in which the quartz or borosilicate filters were placed in series, allowing the separation of particles into two bands of size (particles with diameter between 10 µm and 2.5 µm and particles smaller than 2.5 µm).

 

Preparation of the aqueous suspensions of PM 

 

    The extraction of the particles from the filters occurred in physiological solution by stirring in an ultrasonic bath for 8 hours, and after the extraction, the remaining particulate was dried at 50 °C. From the quantity of the particulate matter mass, aqueous solutions were prepared, stored in Eppendorf microtubes of 1.5 mL, and frozen. The efficiency of the extraction was calculated by the difference in the weight of the filters before and after the process.

 

Experiment with animal model 

 

    Forty-eight male Wistar rats aged between 30 and 45 days, weighing around 220 grams from Feevale University Vivarium were used. During the experiment, the animals were kept in a collective cage with a maximum of five individuals, with industrialized food and water ad libitum, in a room with heated temperature and humidified (22 ± 1 °C and 50 ± 10 % RH) and 12 hours light/dark cycle. The Guía para el cuidado y uso de animales de laboratorio (National Research Council, 2011) was used as a standard guide for the care with animals. All procedures were approved by the Ethics Committee for Animal Research of Feevale University under the number: 02.18.062.

 

    The forty-eight rats were randomly divided into 6 groups of 8 animals each. Group 1 (Control) with no exposure to particulate matter and without aerobic physical training. G2 (aerobic physical training), with no exposure to particulate matter and submitted to aerobic physical training. G3 (PM_2.5), exposed to fine particulate matter and with no submission to aerobic physical training. G4 (PM_2.5 + aerobic physical training), exposed to fine particulate matter and submitted to aerobic physical training. G5 (PM₁₀) exposed to coarse particulate matter and with no submission to aerobic physical training. G6 (PM₁₀ + aerobic physical training), exposed to coarse particulate matter and submitted to aerobic physical training.

 

    The experiment had a protocol adapted based on the research of Fashi et al. (2015), in which for five weeks the animals of the groups were submitted to physical training and nasal instillation five times a week. (Fashi et al., 2015)

 

    On the first week to 3 days intercalated (Monday, Wednesday, and Friday), the animals of groups 2, 4, and 6 were submitted to the adaptation of the ergometric treadmill for humans adapted for rats, model Runner Brasil, during 15 minutes at a speed of 10 m/min.

 

    On the next week, an individual maximum speed test for the exercise was performed, so that the training intensity could be established, in which the animals were submitted to a warm-up of 5 minutes at a speed of 5 Hz/min, followed by a treadmill speed increase of 3 Hz/min, every 3 minutes until the exhaustion of the animal. The mean speed was calculated so that the rats could be submitted to aerobic training on the treadmill, to a moderated intensity, corresponding to 50% of the maximum speed obtained at the test, for 60 minutes, five times a week, for 4 weeks.

 

    The exposures to the particulate matter were performed through nasal instillation utilizing a micropipette (Osier, & Oberdörster, 1997). For the groups 1 and 2 (control), the animals received 50 µl of distilled water in each nostril; in groups 3 and 4, 50 µl of an aqueous suspension of PM_2,5 (250 µg/ml) was used in each nostril. For the groups 5 and 6, 50 µl of an aqueous suspension of PM₁₀ (1000 µg/ml) was used in each nostril. In groups 4, and 6, the exposure to the particulate matter and the aerobic physical training was performed concomitantly.

 

    After four weeks of instillation and training, the animals were anesthetized with ketamine (10 mg/Kg) and xylazine (75 mg/Kg) and decapitated for the blood collection.

 

Oxidative stress 

Processing of biological material 

 

    Oxidative stress (OS) was verified from the blood collection of the animals. The material was distributed into two tubes, one containing EDTA and the other one containing heparin. They were centrifuged at 2500 rpm for 10 minutes and plasma aliquots were separated into Eppendorf tubes, labels, and stored at -80 °C until measurement of OS. The remaining red blood cells of the heparin tubes were processed for the determination of catalase activity (CAT)

 

Laboratory dosages 

 

    Oxidative stress was evaluated through the dosages of SOD (Indirect method of nitro-tetrazolium blue – NTB), catalase (Aebi, 1984), glutathione peroxidase (Pleban et al., 1982) and total antioxidant power. (Benzie, & Stain, 1996)

 

Extracellular superoxide dismutase enzymatic activity 

 

    For the determination of superoxide dismutase (SOD) activity a Fluka kit 19160 (Steinheim, Germany) was used, which is based on the indirect method of nitro-tetrazolium blue (NTB). This assay uses xanthine and xanthine oxidase to generate superoxide radicals that reacts with 2-(4-iodophenyl)-3-(4-nitrophenyl)-5-phenyltetrazoliumchloride to produce formazan, a compound that absorbs light at 450 nm. The inhibition of the chromogen production is proportional to SOD activity present in the sample. The reading was performed in microplates in a spectrophotometer and the results were expressed as % SOD inhibition.

 

Catalase 

 

    The method described by Aebi (1984) was used to determine the catalase activity. The heparin tubes containing blood were centrifuged at 2500 rpm for 10 minutes and the plasma and leukocytes were discarded. After, the red blood cells were washed with a solution of NaCl 0.9% for 3 times. An aliquot of 1 mL of red blood cells was transferred to another tube, in which 4 mL of water was added (Diluent 1). To 20 µL of diluent 1, it was added 9980 µL of a phosphate buffer solution pH 7.0 (Diluent 2). The reading was performed using a spectrophotometer Varian, model Dig Varian Cary (50 NSEL03127475) at 240 nm at 0 and 15 s. For each sample to be read, a blank tube was made. The blank tube was composed of 0.5 mL buffer + 1 mL of Diluent 2. The samples were composed of 0.5 mL of 30 mM hydrogen peroxide solution + 1 mL Diluent 2. The results were expressed in s and corrected by the patients’ hemoglobin.

 

Glutathione peroxidase (GPx) 

 

    Glutathione peroxidase enzymatic activity was performed based on the method described by Pleban et al. (1982). First, a working reaction was prepared with 50 mmol/L Tris buffer pH 7.6, containing per liter 1 mmol Na2EDTA, 4 mmol sodium azide and 1000 U glutathione reductase. The solution was incubated for 5 minutes at 37 °C. For the determination of the enzymatic activity in plasma, 50 µL of undiluted plasma was added to 950 µL of the working reaction. The GPx activity was expressed as U/L of plasma. After the period of 30 seconds, the decrease in absorbance was linear with time. For the beginning of the reaction, 10 µL of 8.8 mmol/L H2O2 was added followed by the decrease of NADPH at 340 nm for 3 minutes. A blank tube was made, in which water was added instead of plasma.

From the results obtained, calculations were performed according to the following equation:

 

K= [2.3/(t₂* - t₁*)] x log [GSH* at t₁ (1 min)/GSH at t₂ (3 min)]

(Faraji, Kang, & Valentine, 1987)

*t₁ = reading on time 1; *t₂ = reading after three minutes; *GSH = glutathione reductase

 

Total antioxidant power 

 

    Total antioxidant power was determined through the method described by Benzie and Strain (1996) which is based on the iron reducing power. FRAP (ferric reducing/antioxidant power) is a test of direct measure of “total antioxidant power”. For the determination of “total antioxidant power”, the plasma of the animals was placed in contact with FRAP (TPTZ - 10 mM 2,4,6-tripyridyl-s-triazine in 40 mM HCl; 300 mM acetate buffer pH 3.6; 20 mM FeCl₃·6H₂O), being this solution reduced when in low pH and in the presence of antioxidant, forming an intense blue coloration, which was monitored by measuring the change in absorption at 593 nm. The change in absorption was directly related to the combination of “total” reducing power of antioxidant electron donors present in the reaction mixture. The “total antioxidant power” was calculated using ascorbic acid and ferrous sulfate solution as standard. (Benzie, & Strain, 1996)

 

Statistical analysis 

 

    Data were expressed as mean ± standard deviation. The results obtained were analyzed by One-way ANOVA, followed by Tukey post-hoc test when the F value was significant or p < 0.05, and by the Pearson correlation test. The analyses were performed using Statistical Package for the Social Sciences Software (SPSS) version 24.0.

Results 

 

Evaluation of the body weight parameter of rats 

 

    At the beginning of the experiment, the animals were between 30 and 45 days of age and the initial individual weight of the animals was measured. The weight evolution could be followed right after the experiment, through the weekly weightings, and on the day of the euthanasia, when the last measurement was performed. In this way, the weight evolution of each group was obtained, as shown in Table 1.

 

Groups	Initial weight (g)	Final weight (g)	Weight difference (g)	Weight difference (%)
G1	216.9 ± 20.1	357.7 ± 24.6	140.7 ± 17.6*	66.4 ± 14.6*
G2	221.7 ± 35.9	344.8 ± 36.0	123.1 ± 20.6*	57.2 ± 15.2*
G3	207.9 ± 35.8	351.1 ± 36.2	143.2 ± 22.5*	71.3 ± 19.7*
G4	195.9 ± 25.8	334.8 ± 23.5	138.9 ± 40.8*	73.8 ± 28.2*
G5	195.6 ± 14.4	321.8 ± 25.4	130.0 ±19.1*	66.7 ± 10.3*
G6	282.1 ± 38.4	355.3 ± 47.9	73.6 ± 19.5*	26.1 ± 6.2*

Data are expressed as mean ± standard deviation (SD), all groups with n=8, G1 (Control); G2 (Control with exercise); G3 (PM_2.5 without exercise); G4 (PM_2.5 with exercise); G5 (PM₁₀ without exercise); G6 (PM₁₀ with exercise). *p<0.05 indicating significant differences, One-way ANOVA followed by Tukey post-hoc test.

 

    No significant difference was evidenced between the initial and final weight among groups. However, there was a significant difference between the initial and final weight within each group. Besides, when the groups that inhaled the same material were compared, it was possible to observe that those submitted to aerobic exercises had a smaller average weight difference when compared to the sedentary animals, and that the group which inhaled PM₁₀ along with aerobic physical training (G6) demonstrated a substantially lower average weight difference when compared to all other groups.

 

Evaluation of oxidative stress parameters 

 

    For the evaluation of the oxidative stress, laboratory analyses were performed from the animals’ blood, which was collected at the end of the experiment. In Table 2, total antioxidant power (FRAP); catalase (CAT); superoxide dismutase (SOD); and glutathione peroxidase (GPx) parameters are presented.

 

Groups	G1	G2	G3	G4	G5	G6
FRAP	609.5	632	674.5	682	643	577.5
	457.3 — 759.5	534.7 — 856.5	608.7 — 818.5	606.75 — 965.5	392.5 — 955	329.7 — 781.3
CAT	3.1	5.5	3.8*	5.7	14.9*	1.1*
	0.6 — 45.1	1.8 — 30.9	1.8 — 5.9	3.1 — 8.6	2.5 — 108.8	0.3 —5.3
SOD	675	1000	1150	625	1400	600
	200 — 1237.5	712.5 — 1975	362.5 — 3112.5	162.5 — 1312.5	750 — 4375	362.5 — 1950
GPx	150.3	119.6	70.7*	28.6*	171.5*	158.5
	43.2 — 238.5	101.25 — 166.3	26.3 — 147.3	13.5 — 46.6	88.1 — 370	56.5 — 228

Data are expressed as mean and interquartile range (25 – 75), n=8, G1 (Control); G2 (Control with exercise); G3 (PM_2.5 without exercise); G4 (PM_2.5 with exercise); G5 (PM₁₀ without exercise); G6 (PM₁₀ with exercise). Total antioxidant power = FRAP; catalase = CAT; superoxide dismutase = SOD; glutathione peroxidase = GPx. *p<0.05 indicating significant differences, One-way ANOVA, followed by Tukey post-hoc test.

 

    The parameters that presented significant differences were catalase and glutathione peroxidase between G3 (PM_2.5 without exercise) and G5 (PM₁₀ without exercise), demonstrating an increase in the antioxidant activities in PM₁₀ in relation to PM_2.5. Group G6 (PM₁₀ without exercise) had a significant decrease in the catalase activity in relation to G5 (PM₁₀ without exercise). And glutathione peroxidase was significantly different between G4 (PM_2.5 with exercise) and G5 (PM₁₀ without exercise), in which G5 had greater antioxidant activity than G4.

 

Correlation test 

 

    Pearson correlation test was performed on the weight differences, total antioxidant power, catalase, superoxide dismutase, glutathione peroxidase, and solution inhaled by the animals (distilled water or aqueous solution with PM_2.5 or aqueous solution with PM₁₀).

 

    A correlation between the weight difference and the inhaled solution was observed (r = 0.296 and p = 0.041). The groups that inhaled distilled water had a greater difference between the initial and final weight than those that inhaled PM_2.5 and PM₁₀ consecutively, thus denoting a negative correlation.

 

Discussion 

 

    Particulate matter can influence various physiological processes associated with health, and among them are the metabolic effects, which directly affect the body weight. In this research, all groups presented an increase in body mass during the experiment, which was considering that they were in the growth phase of their life (Marmett et al., 2018), once the animals started when they were between 30 and 45 days of age and they are considered young adults only when they are 90 days. (Institute of Laboratory Animal Resources, Commission on Life Sciences, National Research Council, 2003)

 

    When comparing the groups that inhaled the same material, it was observed that the groups submitted to aerobic exercises had a smaller difference in the average weight when compared to the sedentary ones. This can be justified by the aerobic physical exercise that attenuates mass gain, probably due to energy expenditure, resulting in a negative energy balance, and consequently, reducing the mass gain (Marmett et al., 2018). Besides, the exposure to atmospheric pollution is related to weight gain and adiposity, and can distort the metabolic balance, once it causes mitochondrial damage and accumulation of white adipose tissue, in comparison to brown adipose tissue, which is metabolically active. (Hoffman et al., 2017)

 

    The G6 presented a smaller weight gain in the difference between the initial and final weight in relation to the other groups. This fact can be justified considering that this group presented a higher initial weight than the others. However, although not significantly, this group did not reach the plateau, which according to the Institute of Laboratory Animal Resources, Commission on Life Sciences, National Research Council (2003), it is on average 500 g. and G6 final weight was similar to the other groups.

 

    Fashi et al. (2015) evaluated the effects of aerobic exercise on a pulmonary inflammation and on the risk of lung cancer in rats exposed to PM₁₀, and presented results similar to those obtained in this study, in which the group submitted to aerobic exercise associated with the instillation of PM₁₀ had a lower average weight gain in comparison to the control group and to the group that received only the inhaled PM₁₀.

On the Pearson correlation test between the weight, oxidative stress markers and the solution inhaled by the animals, a negative correlation was obtained. The larger the particle size instilled, the smaller the difference in weight. This correlation suggests that PM₁₀ can be attributed to metabolic disturbances associated with weight gain.

 

    On the oxidative stress parameter, researches indicate that the particulate matter interferers on a negative manner on the production of biological markers (Rao et al, 2018; Zhou et al., 2017). In this study, we demonstrated that PM_2.5 and PM₁₀ groups without physical exercise presented significant differences in the values of CAT and GPx. Demonstrating that PM₁₀ triggered higher oxidative stress when compared to PM_2.5.

 

    CAT presented a significant difference between the groups that inhaled PM₁₀ without exercise and the PM₁₀ with exercise. GPx presented a difference between PM₁₀ without exercise and PM_2.5 with exercise, demonstrating that the groups with aerobic physical training caused less oxidative stress when compared to the other groups.

 

    Experimental studies demonstrated that after the protocol application of aerobic physical training, a significant reduction on the oxidative stress in rats exposed to pollution occurs (Kostrycki, 2016; Nesi et al., 2016). Corroborating with this study, Matt et al. (2016) evidenced that physical exercise decreases the impact of high concentrations of PM on the airways. The coarse particles are more retained on the upper airways (Cançado et al., 2006), this suggests that G6 could have a lower stress oxidative in relation to the other groups, possibly due to the fact that the aerobic physical training could have reduced the concentration of this particulate matter retained in the upper airways.

 

    On the oxidative stress parameters evaluated in this study, CAT and GPx enzymes were those that presented significant differences between the groups. The effects of the aerobic exercise on oxidative markers demonstrate that physical training directly implies the decrease of free radicals, and consequently on the oxidative stress when exposed to particulate matter.

 

Conclusions 

 

    Our findings demonstrated that the particulate matter affects weight gain and the generation of antioxidant enzymes in Wistar rats. The isolated aerobic physical training protocol, that is, without the inhalation of particulate matter did not present significative difference in relation to oxidative stress when compared to the groups without aerobic training. When comparing the physically active and exposed to PM groups, with the sedentary and exposed to the pollutant groups, it is observed that the aerobic exercise generated a protective effect against the damages caused by the particulate matter.

 

References 

 

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Banerjee, A.K., Mandal, A., Chanda, D., & Chakraborti, S. (2003). Oxidant, antioxidant and physical exercise. Molecular and cellular biochemistry, 253(1-2), 307-312. Retrieved from: https://doi.org/10.1023/A:1026034312124

 

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Lecturas: Educación Física y Deportes, Vol. 25, Núm. 270, Nov. (2020)