Eficácia de dietas ocidental e de cafeteria como protocolo para indução de obesidade em ratos Wistar

Abstract

Obesity is a increasing public health problem. It is characterized by excess body fat, related to endocrine and metabolic disorders. In recent years, studies have been intensified in order to identify the mechanisms involved in the prevention, development and treatment of obesity, including studies with animal models. Currently there are several methods of inducing obesity in animals, however, diet induction is the one that best mimics the disease. The objective of the present study was to compare the effectiveness of obesity induction by offering new western or cafeteria diets, focusing on the evaluation of metabolic, somatic, oxidative, histological and behavioral parameters of Wistar rats. Initially, 24 male Wistar rats were randomized into three groups: CON: control; WTD: experimental western diet, CAF: experimental cafeteria diet. CON consumed throughout the experiment the AIN93-M diet, the WTD group consumed a diet elaborated with modified AIN93-M ingredients added to highly caloric and palatable foods, and finally the CAF group which consumed, in addition to the AIN93-M diet, industrialized foods arranged on a menu varying in four foods per day. Daily monitoring of food consumption and weekly monitoring of weight was carried out. The duration of the experiment was 107st days. From the 101st to the 103st day of the experiment, behavioral tests were performed. On days 104st and 105st, glucose and insulin tolerance tests were carried out, respectively. At the end of the experiment, the murinometric parameters were checked and the animals euthanized. After the euthanasia, the following analyses were performed: total cholesterol (TC), low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TG), aspartate amino transferase (AST), alanine amino transferase (ALT), urea, creatinine, histology of the liver, kidneys and brain, and immunohistochemistry of adipose tissue using interleukin 6 as marker, oxidative parameters in serum, liver, kidneys, brain and body composition. Weight and body mass index (BMI), Lee and adiposity had increased in the CAF group when compared to the other groups. Obesogenic diets reduced glucose and insulin tolerance in rats. The WTD and CAF groups developed dyslipidemia and increased aminotransferase concentration; only the CAF group showed elevated urea concentrations. Hepatic steatosis and ischemic neurons were found for both the obese and interstitial nephritis groups only in the CAF group. There was an increase in lipid peroxidation and reduction of antioxidant capacity in the livers, kidneys and brains of the WTD and CAF groups. The cafeteria diet was effective in causing anxious and depressive behavior in animals. It was concluded that the cafeteria diet was more effective in inducing obesity, being proven both by the somatic parameters and by the greater diversity of metabolic and neurobehavioral disorders related to the disease in the evaluated rats.