Victor F. Motta; Marcia B. Aguila & Carlos A. Mandarim-de-Lacerda

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.

KEY WORDS: HIIT; Obesity; Insulin Resistance; Hepatic Steatosis; Stereology.

MOTTA, V. F.; AGUILA, M. B. & MANDARIM-DE-LACERDA, C. A. High-intensity interval training beneficial effects in diet- induced obesity in mice: adipose tissue, liver structure, and pancreatic islets. Int. J. Morphol., 34(2):684-691, 2016.