Development of an innovative method to study in vitro the impact of environmental stressors on adipose tissue : precision-cut adipose tissue slices on northern elephant seal and pig

Adipose tissue is well known for its insulation and energy storage functions. Yet, its endocrine role has recently been highlighted. Capable of interacting with the whole of the organism, this tissue plays an essential role in body regulation. While the organism undergoes stress, fat is greatly regulated to provides the required energy. It has been, now, established that adipose tissue was a target of environmental endocrine disruptors. However, there is a lack of information about the consequences of this exposition to contaminants. To study in vitro this tissue, the method of precision-cut adipose tissue slices has been elaborated. The aim of this master thesis was the development of the precision-cut adipose tissue on northern elephant seals (NES) as a marine mammal model and pig as a human health model. The NES model was used to study the impacts of environmental contaminants and stress hormones on adipose tissue. For the first time, we tried the precision-cut fat slices method on pig subcutaneous (SAT) and visceral adipose tissue (VAT) for future human health investigations. To analyze the effect of environmental contaminants, we cultured precision-cut blubber slices of NES in the presence of 1nM of bisphenol A and bisphenol S and used 100nM epinephrine and the physiologic dose of 2µM of cortisol as stress hormones. Our experiment pointed out a significant increase in epinephrine induced lipolysis on NES blubber in the presence of a physiologic dose of cortisol through glycerol quantification and gene expression analyses. We did not observed changes in lipolysis for blubber slices exposed to bisphenols. The basal lipolysis of blubber cultured with bisphenols and cortisol could not be measure with the available devices. Yet, further measurements for media contents and genes expressions are in progress. This test revealed the feasibility of using hormones naturally present in NES with the method of the precision-cut blubber slices to highlight a higher lipolysis caused by coupled epinephrine and cortisol. For this first application of precision-cut fat slices method on pig SAT and VAT, we exposed slices to 1µM of isoproterenol and two levels of glucose in culture media. Only SAT lipolysis induced after 36 hours significantly exceeded non-induced lipolysis conditions. Through visualization of slices histologic sections and glycerol released measurements, SAT revealed the presence of nearby dermis and VAT seemed well damaged. Significant changes in adipocytes shapes were observed between induced lipolysis and non-induced lipolysis of SAT. This experiment provided precious information for further improvement and adjustment of the precision-cut fat method applied to the pig model.