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      Efeito do treinamento físico moderado e intenso sobre os mecanismos de defesa de ratos adultos Translated title: Effect of moderate and intense physical training on the mechanisms of defense in adult rats

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          Abstract

          OBJETIVO: Analisou-se o impacto do treinamento físico moderado (TFM) e intenso (TFI) sobre o perfil leucocitário e a atividade microbicida de macrófagos alveolares, em 29 ratos machos Wistar. MÉTODOS: Foram formados três grupos: controle-sedentário (CS), treino-moderado (TM) e treino-intenso (TI). Os TFM e TFI foram efetuados através da natação, com aumento progressivo de carga conforme o peso corporal, até um máximo de 3% para o TFM, e 5% para o TFI. As coletas de sangue para contagem total e diferencial dos leucócitos foram automatizadas através do analisador hematológico Sysmex XT- 1800i (Roche®) antes e após o treino. E ao final realizou-se o lavado broncoalveolar para determinar a taxa de fagocitose e a produção de óxido nítrico (ON) de macrófagos. RESULTADOS: O grupo TM apresentou valores maiores para o número de leucócitos (12,77±2,0 x 17,25±2,4 10³/mm³), linfócitos (8,87±1,0 x 12,5±2,1 10³/mm³) e neutrófilos (0,99±0,5 x 3,18±1,0 10³/mm³), p<0,05. Apresentou também uma maior produção de ON (15,77±4,9µmols/mL) e da taxa de fagocitose (38,6%±8,65) em relação ao CS (6,58±1,9µmols/mL e 24,4%±7,40, respectivamente). Enquanto que, o grupo TI apresentou menor taxa de fagocitose (13,1%±1,52 x 24,4%±7,40), maior produção de ON (38,40± 2,1x 6,58±1,9 µmols/mL) e aumento apenas, no valor dos neutrófilos (2,6±1,4x 0,99±0,5 10³/mm³) quando comparado ao CS, p<0,001. CONCLUSÕES: O TFM proporcionou melhora nos mecanismos de defesa dos animais adultos. Enquanto que o TFI reduziu a taxa de fagocitose o que poderá implicar em prejuízo da atividade microbicida dos animais.

          Translated abstract

          OBJECTIVE: To assess the impact of moderate (MPT) and intense physical training (IPT) on the white blood cell profile and the microbicide activity of alveolar macrophages in 29 Wistar male rats. METHODS: The sample was separated into three groups: control group (sedentary), moderate training (MT), and intense training groups (IT). Swimming was the tool used to classify both moderate and intense training groups with a progressive increase of exercise load regarding body weight (up to 3% for the moderate physical training and 5% for the intense training group). The blood samples used to count total and differential leucocytes were automated by a hematological analyzer Sysmex XT-1800i (Roche®) before and after training sessions. At the end of the process, a bronchoalveolar lavage was carried out so to determine the amount of phagocytosis and the production of nitric oxide (NO) of the macrophages. RESULTS: The MT showed an increase in the number of leucocytes (12,77±2,0x17,25±2,4 10³/mm³), lymphocytes (8,87±1,0x 12,5±2,1 10³/mm³) and neutrophils (0,99±0,5x3,18 ±1,0 10³/mm³), p<0,05. There was also a higher production of NO (15,77±4,9µmols/mL) as well as a higher phagocytosis rate of (38,6%±8,65) as to the control group (6,58±1,9 µmols/mL and 24,4%±7,40, respectively). Whereas the IT showed a smaller phagocytosis rate (13,1%±1,52x 24,4%±7,40), a greater production of NO (38,40±2,1 x 6,58±1,9 µmols/mL) and an increase only in the number of neutrophils (2,6±1,4 x 0,99±0,5 10³/mm³) compared to the control group, p<0,001. CONCLUSIONS: The MPT induced a significant improvement in the defense mechanisms of the adult rats. On the other hand, the IPT induced a reduction in phagocytosis rate which could lead to the microbicide activity of the rats being damaged.

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          Most cited references37

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          Physical activity and modulation of systemic low-level inflammation.

          It has been recognized for some time that cardiovascular disease and type 2 diabetes are, to a major extent, inflammatory disorders associated with an environment characterized by a sedentary lifestyle together with abundant intakes of calories. Systemic low-level inflammation is suggested to be a cause as well as consequence of pathological processes with local tumor necrosis factor alpha production as an important biological driver. It is hypothesized that physical inactivity contributes to an enhanced proinflammatory burden independently of obesity, as regular muscle contractions mediate signals with myokines/cytokines as important messengers, which suppress proinflammatory activity at distant sites as well as within skeletal muscle. Muscle-derived interleukin (IL)-6 is considered to possess a central role in anti-inflammatory activities and health beneficial effects in relation to physical exercise. It is discussed how this fits the consistent observation that enhanced plasma levels of IL-6 represent a strong risk marker in chronic disorders associated with systemic low-level inflammation and all-cause mortality.
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            Is infection risk linked to exercise workload?

            D Nieman (2000)
            Anecdotal, survey, and epidemiological data suggest that endurance athletes are at an increased risk for upper respiratory tract infection (URTI) during periods of heavy training and the 1 - to 2-wk period after race events. The majority of athletes, however, who participate in endurance race events do not experience illness. Of greater public health importance is the consistent finding of a reduction in URTI risk reported by fitness enthusiasts and athletes who engage in regular exercise training while avoiding overreaching/overtraining. Although it naturally follows that infection risk should in some way be linked to acute and chronic exercise-induced alterations in immunity, attempts thus far to measure this association have been unsuccessful. There is growing evidence that for several hours subsequent to heavy exertion, several components of both the innate and adaptive immune system exhibit suppressed function. The immune response to heavy exertion is transient, however, and further research on the mechanisms underlying the immune response to prolonged and intensive endurance exercise is necessary before meaningful clinical applications can be drawn. Some attempts have been made through chemical or nutritional means (e.g., indomethacin, glutamine, vitamin C, and carbohydrate supplementation) to attenuate immune changes after intensive exercise to lower the risk of infection. No consistent relationship between nutritional interventions, exercise immunology, and alteration in URTI risk has yet been established.
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              Exercise-induced alterations in neutrophil degranulation and respiratory burst activity: possible mechanisms of action.

              Neutrophils constitute 50-60% of all circulating leukocytes; they present the first line of microbicidal defense and are involved in inflammatory responses. To examine immunocompetence in athletes, numerous studies have investigated the effects of exercise on the number of circulating neutrophils and their response to stimulation by chemotactic stimuli and activating factors. Exercise causes a biphasic increase in the number of neutrophils in the blood, arising from increases in catecholamine and cortisol concentrations. Moderate intensity exercise may enhance neutrophil respiratory burst activity, possibly through increases in the concentrations of growth hormone and the inflammatory cytokine IL-6. In contrast, intense or long duration exercise may suppress neutrophil degranulation and the production of reactive oxidants via elevated circulating concentrations of epinephrine (adrenaline) and cortisol. There is evidence of neutrophil degranulation and activation of the respiratory burst following exercise-induced muscle damage. In principle, improved responsiveness of neutrophils to stimulation following exercise of moderate intensity could mean that individuals participating in moderate exercise may have improved resistance to infection. Conversely, competitive athletes undertaking regular intense exercise may be at greater risk of contracting illness. However, there are limited data to support this concept. To elucidate the cellular mechanisms involved in the neutrophil responses to exercise, researchers have examined changes in the expression of cell membrane receptors, the production and release of reactive oxidants and more recently, calcium signaling. The investigation of possible modifications of other signal transduction events following exercise has not been possible because of current methodological limitations. At present, variation in exercise-induced alterations in neutrophil function appears to be due to differences in exercise protocols, training status, sampling points and laboratory assay techniques.
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                Author and article information

                Contributors
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Role: ND
                Journal
                motriz
                Motriz: Revista de Educação Física
                Motriz: rev. educ. fis.
                Universidade Estadual Paulista (Rio Claro )
                1980-6574
                December 2012
                : 18
                : 4
                : 699-707
                Affiliations
                [1 ] Universidade Federal de Pernambuco Brazil
                [2 ] Universidade Federal de Pernambuco Brazil
                [3 ] Universidade Federal de Pernambuco Brazil
                [4 ] Universidade Federal de Pernambuco Brazil
                [5 ] Universidade Federal de Pernambuco Brazil
                [6 ] Universidade Federal da Paraíba Brazil
                [7 ] Universidade Federal de Pernambuco Brazil
                Article
                S1980-65742012000400008
                10.1590/S1980-65742012000400008
                6c466844-d22f-4312-902e-f9f5f80929ee

                http://creativecommons.org/licenses/by/4.0/

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                SciELO Brazil

                Self URI (journal page): http://www.scielo.br/scielo.php?script=sci_serial&pid=1980-6574&lng=en
                Categories
                SPORT SCIENCES

                Sports medicine
                Physical exercise,Leukocytes,Phagocytes,Nitric oxide,Exercício físico,Leucócitos,Fagocitose,Óxido nítrico

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