Browning is activated in the subcutaneous white adipose tissue of mice metabolically challenged with a high-fructose diet submitted to high-intensity interval training.

Fructose may induce an endocrine dysfunction in adipose tissue in rodents. Browning is identified by deposits of beige adipocytes in subcutaneous white adipose tissue (sWAT). We study the effects of the high-intensity interval training (HIIT) on the formation of beige adipocytes in the sWAT of mice fed a high-fructose diet. Sixty male mice (3 months old; C57BL/6) were fed two diets for 18 weeks (n=30 each): control diet (C) or high-fructose diet (F). At the 10th week, for an additional 8-week period, the groups were (n=15 each) nontrained (NT) or trained (HIIT): C-NT, C-HIIT, F-NT and F-HIIT. We evaluated body mass, energy expenditure and molecular analyses for browning and thermogenic markers in sWAT. The HIIT groups showed significantly lower body mass and increased energy expenditure. The consumption of fructose was linked with an increased sWAT mass. However, HIIT caused a reduction of sWAT mass compared to the NT groups. Energy intake was parallel in the groups, regardless of the diet type and HIIT. Fructose was related to higher glucose and insulin levels and hypertrophied sWAT adipocytes, but HIIT decreased both glucose and insulin levels and led to the appearance of brown fat-like adipocytes dispersed in sWAT with higher expression of browning markers. Also, fructose reduced the sWAT markers of mitochondrial biogenesis and beta-oxidation, which were enhanced by HIIT. In conclusion, HIIT might stimulate the sWAT browning in mice fed a high-fructose diet associated with beneficial changes in mitochondrial biogenesis and beta-oxidation markers, contributing to a whole-body metabolic improvement.

Treating fructose-induced metabolic changes in mice with high-intensity interval training: insights in the liver, white adipose tissue, and skeletal muscle.

Fructose-rich caloric sweeteners induce adverse changes in the metabolism of humans. The study evaluated the effects of high-intensity interval training (HIIT) on a fructose feeding model, focusing on the liver, white adipose tissue (WAT), skeletal muscle, and their interplay. Male C57BL/6 mice were fed for 18 wk one of the following diets: control (C; 5% of total energy from fructose) or fructose (F; 55% of total energy from fructose). In the 10th week, for an additional 8-wk period, the groups were divided into nontrained (NT) or HIIT groups, totaling four groups: C-NT, C-HIIT, F-NT, and F-HIIT. At the end of the experiment, fructose consumption in the F-NT group led to a high systolic blood pressure, high plasma triglycerides, insulin resistance with glucose intolerance, and lower insulin sensitivity. We also observed liver steatosis, adipocyte hypertrophy, and diminished gene expressions of peroxisome proliferator-activated receptor-γ coactivator 1-α and fibronectin type III domain containing 5 (FNDC5; irisin) in this F-NT group. These results were accompanied by decreased gene expressions of nuclear respiratory factor 1 and mitochondrial transcription factor A (markers of mitochondrial biogenesis), and peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase 1 (markers of ß-oxidation). HIIT improved all of these data in the C-HIIT and F-HIIT groups. In conclusion, in mice fed a fructose diet, HIIT improved body mass, blood pressure, glucose metabolism, and plasma triglycerides. Liver, WAT, and skeletal muscle were positively modulated by HIIT, indicating HIIT as a coadjutant treatment for diseases affecting these tissues.NEW & NOTEWORTHY We investigated the effects of high-intensity interval training (HIIT) in mice fed a fructose-rich diet and the resulting severe negative effect on the liver, white adipose tissue (WAT), and skeletal muscle, which reduced the expression of fibronectin type III domain containing 5 (FNDC5, irisin) and PGC1α and, consequently, affected markers of mitochondrial biogenesis and ß-oxidation. Because HIIT may block these adverse effects in all of these three tissues, it might be suggested that it functions as a coadjutant treatment in combatting the alterations caused by high-fructose intake.

High-intensity interval training (swimming) significantly improves the adverse metabolism and comorbidities in diet-induced obese mice.

BACKGROUND: Controlling obesity and other comorbidities in the population is a challenge in modern society. High-intensity interval training (HIIT) combines short periods of high-intensity exercise with long recovery periods or a low-intensity exercise. The aim was to assess the impact of HIIT in the context of diet-induced obesity in the animal model. METHODS: C57BL/6 mice were fed one of the two diets: standard chow (lean group [LE]) or a high-fat diet (obese group [OB]). After twelve weeks, the animals were divided into non-trained groups (LE-NT and OB-NT) and trained groups (LE-T and OB-T), and began an exercise protocol. For biochemical analysis of inflammatory and lipid profile, we used a colorimetric enzymatic method and an automatic spectrophotometer. One-way ANOVA was used for statistical analysis of the experimental groups with Holm-Sidak post-hoc Test. Two-way ANOVA analyzed the interactions between diet and HIIT protocol. RESULTS: HIIT leads to significant reductions in body mass, blood glucose, glucose tolerance and hepatic lipid profile in T-groups compared to NT-groups. HIIT was able to reduce plasma levels of inflammatory cytokines. Additionally, HIIT improves the insulin immunodensity in the islets, reduces the adiposity and the hepatic steatosis in the T-groups. HIIT improves beta-oxidation and peroxisome proliferator-activated receptor (PPAR)-alpha and reduces lipogenesis and PPAR-gamma levels in the liver. In skeletal muscle, HIIT improves PPAR-alpha and glucose transporter-4 and reduces PPAR-gamma levels. CONCLUSIONS: HIIT leads to attenuate the adverse effects caused by a chronic ingestion of a high-fat diet.

High-intensity interval training beneficial effects in diet-induced obesity in mice: adipose tissue, liver structure, and pancreatic islets / Efectos beneficiosos del entrenamiento con intervalos de alta intensidad en la obesidad inducida por dieta en ratones: tejido adiposo: estructura del hígado e islotes pancreáticos

The study aimed to evaluate the impact of high-intensity interval training (HIIT) on adipose tissue, pancreatic islets and liver in mice fed high-fat diet. C57BL/6 male mice were fed one of two diets: standard chow (Lean group - LE) or a high-fat diet (Obese group ­ OB). After the first 12-weeks, the animals were divided into non-trained (LE-NT and OB-NT), trained groups (LE-T and OB-T), and started the exercise protocol. The HIIT protocol in the trained animals (LE-T and OB-T) compared to their counterparts (LE-NT and OB-NT) led to a reduction in size of the pancreatic islets (LE-T vs. LE-NT -40 %, OB-T vs. OB-NT -22 %) and to an increase in insulin immunodensity in pancreatic islet (LE-T vs. LE-NT +35 %, OB-T vs. OB-NT +31 %). Apart from the above results, in adipose tissue, a decrease of the diameter of adipocytes (LE-T vs. LE-NT -23 %, OB-T vs. OB-NT -12 %), a reduction in adiposity index (LE-T vs. LE-NT -49 %, OB-T vs. OB-NT -24 %) and in the liver, a decrease in the context of hepatic steatosis (LE-T vs. LE-NT -57 %, OB-T vs. OB-NT -77 %). These metabolic changes characterize a benefits performance of the HIIT protocol in swimming. HIIT is able to mitigate the bad effects caused by high-fat diet, even with continued intake of this diet in an animal model. HIIT has the advantage of requiring only a few weekly sessions with short duration in each session. These benefits are important to motivate people who nowadays live with a lack of time condition for these activities.

El objetivo fue evaluar el impacto del entrenamiento con intervalos de alta intensidad (EIAI) sobre el tejido adiposo, el hígado y los islotes pancreáticos en ratones alimentados con dieta alta en grasas. Ratones C57BL/6, machos fueron alimentados con una de dos dietas: dieta estándar (grupo magro - MA) o una dieta alta en grasas (grupo obeso - OB). Después de las primeras 12 semanas, los animales fueron divididos en dos grupos, no entrenados (MA-NE y OB-NE) y grupos entrenados (MA-E y OB-E), y comenzaron el protocolo de ejercicio. El protocolo de IEAI en los animales entrenados (MA-E y OB-E) en comparación con sus contrapartes (MA-NE y OB-NE) condujo a una reducción en el tamaño de los islotes pancreáticos (MA-E vs. MA-NE -40 %, OB-E vs. OB-NE -22 %) y al aumento de la inmunodensidad de insulina en los islotes pancreáticos (MA-E vs. MA-NE +35 %, OB-E vs. OB-NE +31 %). Además, en el tejido adiposo se detectó una disminución del diámetro de los adipocitos (MA-E vs. MA-NE -23 %, OB-E vs. OB-NE -12 %), una reducción en el índice de adiposidad (MA-E vs. MA-NE -49 %, OB-E vs. OB-NE -24 %) y en el hígado una disminución de la esteatosis (MA-E vs. MA-NE -57 %, OB-E vs. OB-NE -77 %). Estos cambios metabólicos caracterizan una actuación beneficiosa del protocolo de EIAI en la natación. El EIAI es capaz de mitigar los efectos negativos causados por la dieta alta en grasas, incluso con la ingesta continuada de esta dieta en el modelo animal. La EIAI tiene la ventaja de requir sólo unas pocas sesiones semanales con corta duración de cada sesión. Estos beneficios son importantes para motivar a la personas en las condiciones de falta de tiempo que tienen en la actualidad.