Insulin and cortisol promote leptin production in cultured human fat cells

The aim of this study was to investigate the regulation of leptin expression and production in cultured human adipocytes using the model of in vitro differentiated human adipocytes. Freshly isolated human preadipo-cytes did not exhibit significant leptin mRNA and pro-tein levels as assessed by reverse transcriptase (RT)-polymerase chain reaction (PCR) and radioimmunoas-say (RIA). However, during differentiation induced by a defined adipogenic serum-free medium, cellular leptin mRNA and leptin protein released into the medium increased considerably in accordance with the cellular lipid accumulation. In fully differentiated human fat cells, insulin provoked a dose-dependent rise in leptin protein. Cortisol at a near physiological concentration of 10"8 mol/1 was found to potentiate this insulin effec