Gerbils (Meriones unguiculatus) as a new experimental model of obesity induced by diet

Background. Currently, the number of obese people in the world has reached alarming proportions. During the expansion of adipose tissue, a number of functions such as activation and release of cytokines and hormones may be affected. This causes the body to take a pro-inflammatory pattern, which may affect the proper functioning of many tissues. Thus, studying the mechanisms by which obesity induces physiological disorders is necessary, and may be facilitated by the use of animal models, in particular rodents. We sought to investigate whether the gerbil (Meriones unguiculatus) would be a good experimental model for the study of obesity and metabolic changes resulting from a diet rich in fats and sugars. Methods. 14 gerbils were divided according to weight into two experimental groups and received a a standard diet with 4,15kcal/g (CT; n = 7) or a diet rich in simple carbohydrates and fats with 5,86kcal/g (OB, n = 7) for 11 weeks. The animals had free access to water and food. The weight of each animal and food consumption of each cage were measured weekly and at the end of the experiment, blood, adipose tissue and liver were collected. The following parameters were determined: cholesterol (COL), triglycerides (TGL) and glycemia (GLI) in the plasma; cytokines (IL-6, IL-10 and TNF-α) and hormones (adiponectin and leptin) in adipose tissue; activity of superoxide dismutase (SOD) and catalase (CAT), extraction and differentiation of fat in the liver and liver histology. Results. The consumption of a diet rich in simple fats and carbohydrates led to an increase of total body weight, relative weights of liver and adipose tissue, glucose and triglycerides levels, and TNF-α concentration in adipose tissue. Animals of this group also showed a significant increase of total fat, cholesterol and triglyceride content in the liver, contributing to higher intensity of hepatic steatosis. On the other hand, depletion in the enzyme activity of SOD and CAT in the liver, as well as reduction of IL-10 and adiponectin levels were found in adipose tissue of these animals. Conclusion. Diet consumption consisting of an excess in saturated fat and simple carbohydrates establish the gerbil as an experimental model for the study of obesity and metabolic and liver abnormalities resulting from this disease.