[Hormones and adipocyte development]

Dormant preadipocytes isolated from adipose tissue are able to differentiate into adipocytes in vitro. A few adipogenic hormones (glucocorticoids or prostacyclin, IGF-I and insulin) are sufficient to trigger the differentiation program. In preadipose and adipose cells, glucocorticoids play a cardinal role by regulating the expression of numerous genes and by increasing the production of prostacyclin which acts as an intracrine/autocrine/paracrine effector. Fatty acids and metabolites (including prostacyclin) enhance adipocyte differentiation via the activation of nuclear peroxisome proliferator-activated receptors (PPARs). PPARs then modulate positively the expression of various lipid-related genes involved in triacylglycerol accumulation. These in vitro observations emphasize the importance of the hypothalamic-pituitary-adrenal axis and provide also a link which may take place in vivo between high-fat diets and the excess of adipose tissue development.