Debier, CathyDe Simone, AnaïsAnaïsDe Simone2021Obesity has reached more than 650 million people in 2016. This disease is accompanied by many comorbidities, which is why it is important to prevent and treat it. As current treatments are not optimal, milder natural alternatives are sought through diet, particularly through the consumption of bioactive compounds such as polyunsaturated fatty acids (PUFA). PUFA include 2 main groups: n-3 PUFA and n-6 PUFA. While n-6 PUFA are considered to be proinflammatory and adipogenic, n-3 PUFA seem to exert the opposite effect, being then interesting for prevention and treatment of obesity. Another kind of PUFA that have raised interest these last few years are the conjugated linolenic acids (CLnA). CLnA are plant-based fatty acids derived from alpha-linolenic acid (ALA) and they seem to exert anti-adipogenic properties, however these studies are recent and they are not unanimous. The objectives of these studies are therefore to evaluate impacts of specific PUFA on the development on obesity. To do this, we used an in vivo model that is zebrafish. Four diets were created and all of them were based on basal feed matrix, egg yolk and oil, the latter allowing to differentiate the 4 diets. The first diet was enriched in sunflower oil for its linoleic acid (LA) (n-6 PUFA) content, the second diet was enriched in linseed oil for ALA (n-3 PUFA) content, the third in fish oil for its content in eicosapentaenoic acid (EPA) and docohexaenoic acid (DHA) (2 long chain n-3 PUFA derived from ALA), and the fourth enriched in pomegranate seed oil containing punicic acid (PunA), a CLnA. Those 4 diets were given to 4 groups of fish in normal dose (25-30 cal per fish per day) and to 4 other groups of fish in overdose (80 cal per fish per day) for 7 weeks after the acclimatation phase of 1 week. Results of this experiment demonstrated that after 7 weeks of experiment, our fatty acids of interest have been incorporated to various extend into zebrafish and LA and ALA have been bioconverted into longer fatty acids, although those conversions were not efficient. It was also observed that fish fed with pomegranate seed oil have higher concentration of 18:4 n-3, which could indicate an effect of PunA on ∆6 desaturase. In addition, PunA seems to have been transformed into another fatty acids such as rumenic acid, a conjugate linoleic acid. Our results also demonstrated interesting differences between overfed and normally fed fish. After 7 weeks of experiment, all overfed fish were heavier than normally fed fish, except the fish overfed with pomegranate seed oil. The same observation was made for the BMI and the concentration of total neutral lipids in fish. These results suggest a protective role of pomegranate seed oil in the development of obesity.ObesityZebrafishPolyunsaturated fatty acidsConjugated linolenic acidtext::thesis::master thesisthesis:32909