Efeitos do exercício físico sobre o metabolismo e comportamento de zebrafish (Danio rerio)

Abstract

Obesity is a medical condition characterized by pathological and excessive accumulation of adipose tissue, both visceral and subcutaneous. This condition has significant impacts on health, including the development of severe diseases such as atherosclerosis, type 2 diabetes mellitus, cardiovascular diseases, and other illnesses. For over 40 years, the relationship between physical exercise and oxidative stress has been studied. However, due to the high complexity of the subject, there are still major gaps in understanding, such as the signaling pathways and the real role of antioxidant enzymes during physical exercise, especially when obesity is involved. Analyzing the existing studies, they have been conducted on humans or rodents, which creates an even larger gap when it comes to the Zebrafish (Danio rerio) model. This study presents the results of a new voluntary physical exercise model and the metabolic effects of an exercise protocol on zebrafish fed with a high-fat diet. In the first study, a voluntary physical exercise (VPE) model was developed to be applied in metabolism and behavior studies. 40 Zebrafish (D. rerio) were divided into two groups and subjected to a VPE system, consisting of two interconnected aquaria with a translucent tube and a lateral video camera to measure the animals' physical exercise parameters. The animals showed increased acceleration and maximum velocity and had higher activity frequency during the light period. In this voluntary physical exercise model, improved locomotor performance was observed, without an increase in anxiety or alterations in biochemical parameters related to lipid metabolism. The second study aimed to identify the metabolic effects of a new physical exercise model in zebrafish fed with a high-fat diet. The experiment consisted of a feeding trial lasting twelve weeks, with the last four weeks incorporating a physical exercise protocol. This protocol involved placing fifteen animals in a five-liter aquarium and having them swim at an approximate

speed of 0.8 m/s for 30 minutes per day. The results demonstrated that the group fed with a high- fat diet (HFD) had a significant increase in reactive oxygen species (ROS) production and

superoxide dismutase (SOD) activity. In contrast, the group fed with a high-fat diet and undergoing physical exercise (HFD-EX) showed a remarkable reduction in visceral adipocyte area, hepatic steatosis levels, superoxide dismutase (SOD) activity, and alanine aminotransferase (ALT) levels. These findings suggest that physical exercise has a positive effect on obesity and oxidative stress in zebrafish, offering promising perspectives for future investigations in this field.