Aerobic training in the prevention of nonalcoholic fatty liver disease resultant from obesity in rats

Abstract

Obesity is a public health problem worldwide and is strongly associated with insulin resistance. The latter is associated with nonalcoholic fatty liver disease (NAFLD), a disease characterized by accumulation of fat in the liver that can lead you to organ failure. Currently, the suggested treatment for NAFLD is decrease in fat intake associated with increase in physical activity. However, little is known about the most appropriate training protocols for the prevention or treatment of this disease. This study aims to examine the effects of exercise at the intensity of the 80% of anaerobic threshold (AT) on markers of NAFLD in obese rats. To induce obesity, 90 days old rats, will be maintained with a high fat / higher calorie diet (35% of animal fat / vegetable fat). Control rats will be treated with a balanced diet (AIN-93M). All animals will be submitted to the lactate minimum test to identify the anaerobic threshold (AT) during swimming exercise. Part of the animals from each group will be subjected to swimming training in intensity equivalent to 80% of the individual AT, 1 h / day, 5 days / week for 16 weeks, another part of them will have exercise training suspended after 8 weeks, remaining under observation for additional 8 weeks, while others will remain sedentary throughout the experiment. Glucose tolerance (glucose tolerance test - GTTo), insulin sensitivity (insulin tolerance test - ITT), circulating lipid profile (triglycerides, total cholesterol, HDL and LDL), markers of NAFLD (serum concentrations of hepatic transaminases ALT and AST) and liver total lipids concentrations will be analyzed. Additionally, histological analysis of the liver will be performed by hematoxylin / eosin (HE) and the lipogenic rates will be measured in liver, skeletal muscle and adipose tissue.