Efeitos da dieta hiperproteica restrita em carboidratos e/ou treinamento físico sobre concentração de irisina e parâmetros morfofuncionais do tecido adiposo de ratos Wistar obesos

Abstract

Objective: To evaluate the effects of physical training and/or a high-protein and low-carbohydrate diet on the modulation of plasma and muscle irisin and morphological and functional changes in white and brown adipose tissue of male Wistar rats in an obesity model. Methods: 28 male Wistar rats with obesity induced by a high-calorie diet (HC) were divided into 4 groups: Group submitted to the HC diet and sedentary (n=7); Group submitted to the HC diet and trained (n=7); Group submitted to a high-protein and low-carbohydrates diet (HP) and sedentary; Group submitted to HP diet and trained (n=7). After a period of 12 weeks, the animals were euthanized and the subcutaneous (TASC), epididymal (TAE) and brown (TAM) adipose tissues, as well as the gastrocnemius muscle and thoracic blood were collected for further analysis. Body composition, serum and tissue levels of irisin/FNDC5, gastrocnemius muscle morphology and TASC and TAM were evaluated. Energy metabolism parameters were also evaluated in TASC and TAM and markers of mitochondrial activity, inflammatory profile, oxidative damage and activity of antioxidant enzymes in TASC, TAE and TAM. Statistical analyzes were performed using the two-way ANOVA test (2 diets x 2 training conditions), followed by the Bonferroni post-test. Data were presented as mean±standard error. Results: The HP diet and moderate physical training for 12 weeks reduced body weight and adiposity, as well as the area and diameter of adipocytes in the TASC and increased the weight and area of gastrocnemius muscle fibers, as well as immunostaining of the precursor of irisin (FNCD5) and reduced tissue triglyceride content. Serum irisin concentration increased only as a result of physical training. In TAM, both physical training and diet reduced tissue triglyceride content, however, only training reduced the area occupied by unilocular adipocytes and increased UCP-1 gene expression. Only physical training increased the enzyme citrate synthase, a marker of mitochondrial activity, in TASC, TAE and TAM. Furthermore, training also determined greater beneficial effects on redox balance, increasing gene expression and activity of antioxidant enzymes in TASC and TAM and reducing oxidative markers (TBARS, carbonyl proteins and total nitrites). The inflammatory profile was positively modulated by both the HP diet and physical training, which reduced the TNF-α/IL-10 ratio in TASC, TAE and TAM, increased adiponectin gene expression, as well as immunostaining of NF-κB, MCP -1 and the total macrophage/M2 macrophage ratio in TASC. Singly, physical training increased the anti-inflammatory markers IL-10 and IL-27 and reduced the inflammatory markers IL-6 (TASC and TAM), IL-1β (TAE), as well as total macrophages, crown-like structures and lymphocytes in TASC and NF-κB immunostaining in TAM. Conclusion: In the model studied, the effects of a high-protein diet restricted in carbohydrates and physical training for 12 weeks attenuated the changes caused by obesity on parameters of body composition, tissue morphology and metabolism, and the inflammatory and oxidative profile of adipose tissues. Our findings reinforce the importance of regular physical training as it positively modulate irisin and confer better morphofunctional benefits and on inflammatory and oxidative profiles in adipose tissue deposits of obese animals.