Effect of punicic acid on the development of obesity using Zebrafish as a model

Details

Supervisors

Page, Melissa ; Larondelle, Yvan

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en sciences agronomiques, à finalité spécialisée

Abstract

The prevalence of obesity is increasing worldwide, having tripled since 1975. In 2016, nearly 1.6 billion adults were overweight and obese, and nearly 650 million were obese. This increase is particularly important because it is associated with the risk of developing multiple serious health problems such as diabetes, heart disease and certain cancers. In addition to genetic predisposition, environmental and behavioral factors resulting in increased physical inactivity and calorie intake also contribute to the development of obesity. Among dietary changes, scientific evidence indicates that dietary fat plays a role in weight loss and maintenance. Natural treatments have been shown to have a beneficial effect on obesity-related metabolic disorders, including the consumption of polyunsaturated fatty acids (PUFAs) including linoleic acids (CLA) and conjugated linolenic acids (CLA). Among them, punicic acid (PunA; C18:3cis-9, trans-11, cis-13) is a long-chain omega-5 PUFA and an isomer of CLA found in large percentage in pomegranate seeds (Punica granatum L.). The objectives of this Master's thesis were to investigate the effects of PunA on the development of obesity using zebrafish as a model. A experiment was therefore set up, with the aim of testing whether a diet enriched with PunA reduced obesity in an overfeeding experiment. Four different diets were given to two groups of fish in normal dose enriched with either PunA or sunflower oil (25-30 cal per fish per day) and to two other groups of fish in overdose enriched with either PunA or sunflower oil (80 cal per fish per day) as a diet to feed 3-month-old zebrafish for six weeks. Next, ZFs were sampled to measure the relative expression of genes involved in lipid metabolism, such as FADS, ELOV, RetSat and PTGR, as a function of the four diets. These results show that PunA could potentially have beneficial effects in reducing the increase in body mass and BMI in a PSO-enriched diet compared to an artemia diet enriched with sunflower oil. Overall, there does not appear to be an effect of diet on the gene expression of any of the targets of interest. For lipid metabolism, our results indicated that ZF are not efficient at biotransforming n-3 and n-6 PUFAs into longer and more unsaturated metabolites. Only the expression of the RetSat gene was significantly higher in the OF PSO diet possibly through the activation of PPAR by PunA. These observations raise the interest in incorporating PunA into diets and in continuing to investigate the potential anti-obesity effects of this fatty acid.