Impact of piceatannol on lipolysis of adipose tissues

Details

Supervisors

Debier, Cathy ; Goudmaeker, Apolline

Faculty

Faculté des bioingénieurs

Degree label

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

Abstract

Overweight and obesity concern more than 2 billion people worldwide. It is defined by an excessive accumulation of fat, impairing metabolic functions and leading to diabetes, cardiac alterations, and even cancer. Reducing food intake and increase energy expenditure is an effective strategy to overcome obesity. Medical treatments can also be used, but these are often initiated only in severe cases and are not without consequences. In order to find alternatives to conventional treatments, bio-active compounds found in dietary sources are studied for their anti-obesity proprieties. In this context, piceatannol, a stilbene belonging to the polyphenol family, has shown anti-obesity properties through its impact on adipogenesis, lipogenesis, insulin sensitivity, inflammation and lipolysis. This master thesis investigated the effect of piceatannol on lipolysis occurring in adipose tissues. Inhibiting this pathway would lower free fatty acid release, which is elevated in obese patients, and may improve their global metabolism. Following the studies showing inhibitory effects of piceatannol on lipolysis in differentiated cell culture of mice adipocytes, this study aims at assessing if piceatannol could inhibit lipolysis using a newly developed model of pig precision-cut adipose tissue slices. For this purpose, adipose tissue samples were sliced and pre-incubated with piceatannol at 0.5 mM for 24 hours. Lipolysis was then induced by activation of the beta-adrenergic receptor with a synthetic catecholamine during a 24 hours incubation. The release of glycerol, one of the resulting products of the lipolytic pathway, was measured using an enzymatic assay. First, our results showed that piceatannol lowered the level of glycerol released under stimulated lipolysis conditions, confirming the results previously reported on mice. However, due to issues with enzymatic assays, specific tests were conducted to check if piceatannol could interfere with the enzymatic reactions of the kit. As a result of these tests, piceatannol appeared to strongly interact with the enzymes contained in the glycerol assay kit. Piceatannol is indeed described as an inhibitor of several enzymes. In response to this new element, we decided to quantify lipolysis through another method. To do so, we quantified free fatty acids (FFAs) released in the culture medium by gas chromatography, following lipid extraction and separation. These new investigations revealed that there was no significant difference of FFAs released when the lipolysis was induced with or without piceatannol. These observations indicate that piceatannol does not inhibit lipolysis. The results formerly obtained were due to interference with the glycerol assay kit.