Physical activity prevents alterations in mitochondrial ultrastructure and glucometabolic parameters in a high-sugar diet model

Abstract

Endurance exercise is a remarkable intervention for the treatment of many diseases. Mitochondrial changes on skeletal muscle are likely important for many of the benefits provided by exercise. In this study, we aimed to evaluate the effects that a regular physical activity (swimming without workload) has on mitochondrial morphological alterations and glucometabolic parameters induced by a high-sugar diet (HSD). Weaned male Wistar rats fed with a standard diet or a HSD (68% carbohydrate) were subjected to 60 minutes of regular physical activity by swimming (without workload) for four- (20 sessions) or eight-week (40 sessions) periods. After training, animals were euthanized and the sera, adipose tissues, and skeletal muscles were collected for further analysis. The HSD increased body weight after an 8-week period; it also increased the fat pads and the adipose index, resulting in glucose intolerance and insulin resistance (IR). Transmission electron microscopy showed an increase in alterations of mitochondrial ultrastructure in the gastrocnemius muscle, as well as a decrease in superoxide dismutase (SOD) activity, and an increase in protein carbonylation. Regular physical activity partially reverted these alterations in rats fed a HSD, preventing mitochondrial morphological alterations and IR. Moreover, we observed a decrease in Pgc1α expression (qPCR analysis) in STD-EXE group and a less pronounced reduction in HSD-EXE group after an 8-week period. Thus, regular physical activity (swimming without workload) in rats fed a HSD can prevent mitochondrial dysfunction and IR, highlighting the crucial role for physical activity on metabolic homeostasis.

Muscular glucose metabolism in middle-age trained rats

“…Therefore, exercise prevents glucose intolerance, which is extremely important because glucose intolerant individuals exhibit an increased risk (11%/year) of developing type-2 diabetes compared to normal individuals [33]. Exercise also decreases glucose intolerance [34][35][36].…”

Are Alterations in Skeletal Muscle Mitochondria a Cause or Consequence of Insulin Resistance?

“…Dietary models of insulin resistance (over nutrition or consumption of diets high in sucrose or fat) are often used in rodent studies as they can more closely mirror the development of disease in humans. In Wistar rats fed a high sugar diet, there are alterations of the mitochondrial ultrastructure as well as an increase in CS activity [75]. Regular physical activity in these rats partially returned mitochondrial ultrastructure towards the control values, although CS activity was not significantly altered with exercise in the animals consuming a high sugar diet [75].…”

“…In Wistar rats fed a high sugar diet, there are alterations of the mitochondrial ultrastructure as well as an increase in CS activity [75]. Regular physical activity in these rats partially returned mitochondrial ultrastructure towards the control values, although CS activity was not significantly altered with exercise in the animals consuming a high sugar diet [75]. This suggests improvements in mitochondrial content were not responsible for the improvements in glucose tolerance seen with exercise training in these rats [75].…”

Papel da alça ECA2/Ang 1-7/Mas no músculo esquelético para a prevenção de distúrbios metabólicos por meio do treinamento físico aeróbio

“…Em ratos treinados na natação por 8 semanas e alimentados com dieta rica em açúcar (adição de leite condensado e sacarose), o conteúdo mitocondrial aumentou nos animais sedentários que consumiram a dieta rica em açúcar e nos animais que treinaram, mas não nos animais que consumiram a dieta e treinaram. Assim, parece que a interação treino e dieta pode impedir o aumento no conteúdo mitocondrial como um mecanismo compensatório (DE QUEIROZ et al, 2017).…”

“…Além disso, a dieta pode alterar a integridade das mitocôndrias, pois de acordo com um estudo prévio, animais alimentados com dieta rica em açúcar apresentaram maior percentual de mitocôndrias danificadas (DE QUEIROZ et al, 2017). Em outro estudo, camundongos alimentados com dieta rica em gordura e açúcar por 16 semanas apresentaram queda no conteúdo de mitocôndrias, maior dano e inchaço nas cristas mitocondriais tanto da região SS como da região IMF (BONNARD et al, 2008 Outros estudos demonstraram os efeitos de dietas e do TFA sobre as proteínas do SRA.…”