[Preadipocytes: a new model in obesity research (author's transl)].

The present knowledge about the differentiation of preadipocytes into adipocytes is reviewed. The adipose conversion is initiated by an as yet unknown serum factor and is enhanced by various hormones including insulin, prostaglandin F2 alpha, steroids, and prolactin; prostaglandin E1 and phorbol diesters are inhibitors of differentiation. Adipose conversion of fibroblasts (preadipocytes) is associated with the coordinate induction of key enzymes of the lipogenetic and lipolytic pathways and is accompanied by profound changes in hormone responsiveness. Pathophysiological studies with preadipocytes of genetically obese mice show differences between adipocyte precursors of obese animals and lean controls which may be casually related to obesity. Regional differences in the hormonal regulation of fibroblast conversion might be important for the sex differences of fat deposition in human beings.