Estudo da relação entre estresse oxidativo e sintese de proteinas de estresse "HSP70" no sangue de animais submetidos a diferentes niveis de exercicio fisico

Orientador: Lucia Pereira da SilvaTese (doutorado) - Universidade Estadual de Campinas, Instituto de BiologiaResumo: Nosso estudo investigou em amostras de sangue de ratos do tipo ¿Wistar¿ a correlação entre estresse oxidativo (plasma), modulação do estado antioxidante/oxidante (hemácea) e níveis de proteínas de estresse ¿HSP70¿ (leucócito total) em diferentes sobrecargas de corrida em esteira rolante: exercício exaustivo agudo e treinamentos contínuo e intermitente crônico e severo. Os resultados mostraram que o exercício agudo em animais sedentários induziu um aumento nos níveis dos marcadores oxidativos em plasma (proteínas carboniladas e TBARS) juntamente com uma elevação da atividade das enzimas antioxidantes (catalase e gluationa redutase) e da expressão de ¿HSP70¿ em leucócitos. Os protocolos de treinamento crônico mostraram um mesmo padrão adaptativo: o aumento da sobrecarga de exercícios induziu elevação nos níveis de lesões oxidativas e alterações musculares. Porém, obtivemos nesta situação um aumento de atividade das enzimas antioxidantes e níveis de ¿HSP70¿, o que poderia ser considerado uma resposta adaptativa ao estímulo de treinamento. A estabilização da sobrecarga providenciou um decréscimo nos níveis de estresse oxidativo e expressão de ¿HSP70¿ em ambos os protocolos. Porém, os protocolos de treinamento severo, tanto contínuo quanto intermitente, induziram uma acentuada situação de estresse oxidativo e expressão de ¿HSP70¿. A redução no tempo de recuperação entre as sessões de treinamento e a elevação da sobrecarga de corrida foram fatores agravantes para o aumento da severidade do estresse. Concluindo, os marcadores de estresse oxidativo estudados neste trabalho mostraram uma relação direta entre intesidade do exercício e níveis de lesões oxidativas e alterações musculares. A detecção de ¿HSP70¿ foi um importante índice para monitorar a severidade do estresse. Assim, análises de marcadores de estresse oxidativo em conjunto com a detecção de ¿HSP70¿ poderiam ser uma potente ferramenta para controlar a sobrecarga dos exercícios de treinamento, prevenindo a instalação de situações fisiopatológicas gravesAbstract: The present study was designed to investigate in blood samples of rats if there are a correlationship among oxidative stress, modulation of antioxidant/oxidant status and stress protein levels in differents running overloads: acute exhaustive exercise, and chronic and severe (continuous and intermittent protocols) trainings. Our results showed that the acute exhaustive exercise induced in sedentary rats an increase in plasma oxidative markers (carbonyl derivatives and TBARS) together to an upregulation in the erithrocyte antioxidant enzymes (catalase and glutathione reductase) and elevation in HSP70 in leukocytes. The chronic training protocols showed a same pattern of adaptation: the increase in overload of exercise induced an elevation in the oxidative damage and muscle alterations levels. But we had in this situation an increase in antioxidant enzymes activity and HSP70 expression, what would be an adaptative response to the training stimulus. The overload stabilization provided a decrease in the oxidative stress markers levels and HSP70 expression to both protocols. However, the severe training protocols induced a markedly oxidative stress situation and an increase of HSP70 levels. The reduction in the recovery time between the training sessions together an elevation in overload of exercises were an aggravating factor to the increase in the stress severity. In conclusion, the oxidative stress markers studied here showed a close correlation between exercise intensity and oxidative damage and muscle alterations. The HSP70 detection was an important index to monitore the stress severity. Oxidative stress markers analyses and HSP70 detection could be a useful tool to control the overload of training exercises preventing the installation of pathophysiological situationsDoutoradoBioquimicaDoutor em Biologia Funcional e Molecula

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear understanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5,6,7 vast areas of the tropics remain understudied.8,9,10,11 In the American tropics, Amazonia stands out as the world's most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepresented in biodiversity databases.13,14,15 To worsen this situation, human-induced modifications16,17 may eliminate pieces of the Amazon's biodiversity puzzle before we can use them to understand how ecological communities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple organism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region's vulnerability to environmental change. 15%–18% of the most neglected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lost

Formação de espécies reativas de oxigênio e exercício físico

As espécies reativas de oxigênio (EROs) surgem da instabilidade de seus elétrons desemparelhados, o que gera alto potencial de reatividade com moléculas biológicas. O ataque que é proporcionado possibilita oxidação de estruturas de membranas celulares e até mesmo do ácido desoxirribonucléico (DNA). Em situação extrema, observa-se a instalação do quadro de estresse oxidativo, caracterizado, sobretudo, pela diminuição da atividade do sistema antioxidante. O exercício físico pode ser uma estratégia para elevar os níveis antioxidantes e contribuir com a melhoria de rendimento físico.The reactive oxygen species (ROS) arise from the instability of their unpaired electrons, which generates high potential reactivity with biological molecules. The attack is provided which enables oxidation of cell membranes and structures even deoxyribonucleic acid (DNA). In an extreme situation, we observe the onset of the oxidative stress, mainly characterized by the reduced activity of the antioxidant system. Exercise can be a strategy to increase antioxidant levels and contribute to the improvement of physical performance

Estudo de Marcadores de Estresse Oxidativo em um Triatleta Durante o Período Competitivo

Este estudo avaliou marcadores de estresses oxidativo e fisiológico em um triatleta ao longo de 3 fases específicas de um período competitivo, para determinar se tais marcadores eram capazes de refletir níveis distintos de estresse. Analisamos o estado antioxidante através da atividade da enzima catalase (CAT) no eritrócito, concentração de substâncias reativas ao ácido tiobarbitúrico (TBARS) no plasma, níveis de alterações musculares por meio de creatina quinase (CK) plasmática e marcadores fisiológicos como ácido úrico (AU), creatinina (CRE) e uréia (UR) em amostras de plasma. As análises foram feitas por técnicas espectrofotométricas. Observamos nas análises 1 e 2 um aumento significativo nos níveis de TBARS comparado com o grupo controle e a análise 3; observamos em conjunto com a análise 1 uma queda em atividade de CAT, mostrando uma situação evidente de estresse oxidativo. Contudo, não obtivemos alterações significativas na concentração plasmática de CK na análise 1, indicando que poderia ter havido aumento em permeabilidade de membrana, mas não lesões significativas. Esta situação foi contrária na análise 3, pois obtivemos um decréscimo nos níveis de estresse oxidativo e elevação na concentração plasmática de CK. Alterações musculares podem ocorrer sem evidência de estresse oxidativo ou aumento nos níveis de lesão celular. Neste momento, a atividade de CAT alcançou os índices mais elevados. Não tivemos alterações significativas em marcadores fisiológicos. Os marcadores estudados refletiram os diferentes níveis de estresse impostos durante o treinamento e as competições e mostraram que é possível modular as cargas de treinamento considerando os parâmetros analisados. Palavras-Chaves: triathlon, estresse oxidativo, treinamento físico. ABSTRACT This study evaluated the oxidative and physiological stress markers in a triathlete along three distinct phases of a competitive period to determine if they were able to reflect the different stress levels. We measured the antioxidant status through erythrocyte catalase (CAT); the thiobarbituric acid reactive substances (TBARS) concentrations; the muscular damage levels through plasma creatine kinase (CK) activity and the uric acid, creatinine and urea as physiological markers in blood samples through the spectrophotometric analyses. We found at analyses 1 and 2 a significant increase of plasma TBARS concentration compared with both control group and analysis 3; we observed together the analysis 1 a fall in CAT activity, showing an evidence of oxidative stress situation. However, did not significantly change in CK activity was obtained at analysis 1, indicating an increase in membrane permeability without a severe muscle damage. This situation was observed at analysis 3, where we obtained a decrease in oxidative stress levels and an elevated CK plasma concentration. Muscle damage can occur without evidence of oxidative stress or oxidative damage. At this moment, the CAT activitie increased to the highest levels. We did not have alterations in physiological markers. The markers analyzed reflected the different degree of stress imposed during the training and competitions and showed that is possible to modulate de loads of training considering the parameters studieds. Key Words: triathlon, oxidative stress, physical training.</div