Differentiation of rabbit adipocyte precursors in primary culture.

A primary culture system was used to study the adipose conversion of adipocyte precursors derived from the stromal-vascular fraction of perirenal adipose tissue of rabbit fetuses Differentiation was assessed by the development of glycerol-3-phosphate dehydrogenase, Acid:CoA ligase and lipoprotein lipase activities. Stromal-vascular cells were not able to differentiate when maintained in a medium supplemented with fetal calf serum or with rabbit serum. In contrast, differentiation was induced when the medium was supplemented with rabbit plasma. It also occurred when the growth phase was performed in serum provided that the serum was replaced by plasma when the cultures reached confluence. Supplementation of the culture medium with mesenteric lymph or chylomicrons as lipid sources greatly enhanced both lipid accumulation and the level of enzymatic markers of adipocyte differentiation. Following confluence in serum, cell proliferation ceased almost completely. In contrast, cells in the presence of plasma continued to proliferate, leading to a higher cell density at the time of adipocyte differentiation. These results suggest a positive effect of plasma on the post-confluent mitoses of susceptible cells. To our knowledge, it is the first time that such a difference between plasma and serum has been shown for the differentiation of adipocytes, using an homologous system. These studies also demonstrate that rabbit adipocyte precursors differentiating in primary culture show both similarities to and differences from the adipocytes of cell lines or cell precursors obtained from other animal species.