The dynamics of accumulation of PCBs in cultured adipocytes vary with the cell lipid content and the lipophilicity of the congener.

Lipophilic pollutants such as polychlorinated biphenyls (PCBs) accumulate in high amounts in the adipose tissue. Recent epidemiological studies correlate their presence in fat cells to possible alterations in the regulation of lipid metabolism. The factors governing their accumulation dynamics, storage and release in/from fat cells remain however unclear. Several in vitro models of cultured adipocytes can be used to address these questions. Nevertheless, the cell culture system as well as the PCB congener may influence the behavior of such pollutants toward adipocytes and thus the results obtained. In the present study, we compared the accumulation of 3 PCB congeners (PCB-28, -118 and -153) during a 4-h period in two common models of cultured adipocytes (mouse embryonic fibroblasts (MEFs) differentiated into adipocytes and differentiated 3T3-L1 cells). The results show that adipocytes from different models accumulate significantly different amounts of a same pollutant added at the same initial concentration in the culture medium. These amounts were strongly correlated to the amounts of triglycerides stored in cells. Moreover, the dynamics of accumulation varied between the three congeners, PCB-28 entering the cells more rapidly than the two other congeners. The lipophilicity of these molecules, shown by the partition coefficient (logP) appears to be a major parameter governing their uptake dynamics in fat cells.