US EPA

2930612 

Journal Article 

Efficient in vitro adipocyte model of long-term lipolysis: A tool to study the behavior of lipophilic compounds 

Louis, C; Van Den Daelen, C; Tinant, G; Bourez, S; Thome, JP; Donnay, I; Larondelle, Y; Debier, C 

2014 

Yes 

In Vitro Cellular and Developmental Biology - Animal
ISSN: 1071-2690
EISSN: 1543-706X 

50 

6 

507-518 

English 

24477563 

10.1007/s11626-014-9733-6 

WOS:000338234700005 

The triglycerides (TGs) stored in the white adipose tissue are mobilized during periods of negative energy balance. To date, there is no in vitro model of adipocytes imitating a long period of negative energy balance in which triglycerides are highly mobilized. Such model would allow studying the mobilization of TGs and lipophilic compounds trapped within the adipose tissue (e.g., pollutants and vitamins). The present study aims at developing a performing long-term in vitro lipolysis in adipocytes, resulting in a significant decrease of TG stores. Lipolysis was induced on differentiated rat adipocytes by a lipolytic medium with or without isoproterenol for 12 h. The condition with isoproterenol was duplicated, once with medium renewal every 3 h and once without medium renewal. Adding isoproterenol efficiently triggered lipolysis in a short time (3 h). However, a single stimulation by isoproterenol, without medium renewal, was not sufficient to reduce the TG content during a longer term (12 h). A reesterification of fatty acids occurred after a few hours of lipolysis, resulting in a novel increase of cellular lipids. Regular medium renewal combined with repeated isoproterenol stimulations led to almost emptied cells after 12 h. However, medium renewal without isoproterenol stimulation for 12 h was as efficient in terms of lipid mobilization. Our study demonstrates that, over a short-term period, isoproterenol is required to exert a significant lipolytic effect on adipocytes. During a long-term period, the presence of isoproterenol is no longer essential. Instead, medium renewal becomes the main factor involved in cell emptying. The efficiency of this protocol was demonstrated by visual tracking of the cells and by monitoring the dynamics of release of a lipophilic compound, PCB-153, from adipocytes during lipolysis. 

Adipocyte; Lipolysis; Cell culture; Lipophilic compounds