Adipogenic activities in rat organs.

Adipose conversion of 3T3-L1 cells depends on adipogenic factors present in serum. In order to find their origin, adipogenic activity in extracts from adrenals, kidneys, testes, ovaries, liver, spleen, sceletal muscle and adipose tissue of the rat was studied. If tissues were homogenized with aqueous buffers at low pH, no adipogenic activity could be extracted. Treatment with chloroform/methanol followed by phase separation however revealed considerable adipogenic activity in the organic phase from adrenals, kidneys, ovaries, testes and sceletal muscle and additionally in the aqueous phase of liver. Further purification by liquid chromatography and reversed phase HPLC led to the identification of adipogenic activities from adrenals and kidneys as corticosterone and 11-dehydrocorticosterone. Adipogenic activity from liver in contrast is pronase-sensitive, exhibits an apparent molecular mass of 4 kDa and is probably a peptide.