Avaliação dos efeitos da obesidade induzida por dieta em peixes-zebra (Danio rerio): um estudo comparativo

Abstract

Obesity is a public health problem that, to understand the mechanisms involved, requires experimental models that have genetic equivalence with humans. This research aimed to carry out a comparative study of 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: hyperfed with Artemia salina (60-120 mg/day/fish), all groups were fed for eight weeks. The animals were evaluated regarding dietary intake, caloric intake and efficiency, body mass index (BMI), biochemical and inflammatory parameters and behavior (anxious type). Furthermore, visceral body fat was evaluated through morphological, stereological studies and the expression of genes related to obesity. The obesity group 2, hyperfed with Artemia salina, had higher consumption, intake and caloric efficiency. Weight gain was greater in the two diet-induced obesity (DIO) groups when compared to the control groups, highlighting the obesity group 2 = 167mg (143.5-193.5; p < 0.0001). Blood glucose was higher for males in obesity group 2 (48.33 mg/dL ± 4.14; p < 0.003). Insulin concentration was higher in obesity groups 1 and 2 (both sexes). The concentration of triglycerides was higher in the obesity 1 group (52.67mg/dL±1.2) in both sexes and they presented anxious profile behavior in the new tank test (0.003< p <0.005). A higher concentration of plasma interleukin-6 (IL-6) was observed in the group of male zebrafish from the obesity group 2 (4.24 pg/mL ± 0.18; p < 0.0015), and the necrosis factor tumor (TNF-α) was higher in the two obesity induction groups (16.33; 16.39 pg/mL ± 0.79; p < 0.0003), such results were also confirmed in the gene expression analysis. In morphological studies, extensive areas of lipid deposits, hepatic steatosis, areas of necrosis and inflammatory cells were found in the livers of control groups 2, obesity 1 and 2. Stereology demonstrated volume density (43.6%± 4.40; p = 0.0002) and a larger mean adipocyte sectional area in the obesity group 1 (67.8µm2 ± 18.1; p = 0.0004). The results obtained in this study are of great contribution to the scientific community, as they guide with more specificity the paths to be followed in the investigation of obesity in zebrafish.