Assessment of the effects of diet-induced obesity in zebrafish (Danio rerio): a comparative study
Weight gain, diabetes mellitus, inflammation, dyslipidemia, high-fat diet.
Obesity is a public health problem and understanding the mechanisms involved requires experimental models that have genetic equivalence with humans. In this work, a comparative study was carried out on dietary obesity induction models in zebrafish, evaluating complications. 200 animals were used, adults of both sexes, divided into 4 groups (n=50). Control group 1: fed with Artemia salina (15-30 mg/day/fish); Control group 2: fed with commercial fish food (3.5% of average weight); Obesity group 1: overfed with pasteurized powdered egg yolk mixed with soybean oil (5% of average weight); Obesity group 2: overfed with Artemia salina (60-120 mg/day/fish) for eight weeks. The animals were evaluated for dietary intake, caloric intake and efficiency, body mass index (BMI), behavior, biochemical and inflammatory parameters. Furthermore, visceral body fat was evaluated through morphological, stereological studies and the expression of genes related to obesity. Obesity group 2, hyperfed with Artemia salina, had higher consumption, intake and caloric efficiency. Weight gain was greater (p < 0.0001) in the two diet-induced obesity (DIO) groups compared to the control groups, especially the group with obesity 2. Blood glucose was higher for males in the obesity 1 group Insulin concentration was higher for both males in obesity groups 1 and 2. Triglyceride concentrations were higher in obesity group 1 in both sexes and they showed anxious profile behavior in the new tank test. A higher concentration of plasma interleukin-6 (IL-6) was observed in the group of male zebrafish with obesity induced with Artemia salina (p=0.0015), and tumor necrosis factor (TNF-α) was higher in two obesity induction groups. Gene expression demonstrated elevated inflammatory levels in the obesity induction groups in both sexes. In morphological studies, a more extensive area of adipocytes was observed, significant hepatic steatosis in obesity group 2, the one overfed by Artemia salina. The results obtained in this study are of great contribution to the scientific world, as they guide with more specificity the paths to be followed in the study of obesity in zebrafish.