We have been examining mechanisms by which hormones, particularly glucocorticoids and insulin, influence the adipocyte metabolic capacity and function over the long term. Leptin is produced by the adipocyte and is hypothesized to provide information about the size of fat stores to central receptors regulating energy balance. Data accumulated from recent in vivo and in vitro experiments show that insulin and glucocorticoids synergistically increase leptin mRNA levels and leptin secretion from adipose tissue of severely obese subjects. We are now studying leptin production in lean subjects. Studies are also underway to determine the mechanisms underlying hormonal effects on leptin, and how these differ in human omental vs. subcutaneous adipose tissues.
Isoproterenol decreases leptin expression in adipose tissue of obese humans.
Somatotropin regulates adipose tissue metabolism in neonatal swine. Acute cold exposure decreases plasma leptin in women. Johnson, J., Fried, S.K., Pi-Sunyer, F.X., and Albu, J. Impaired insulin action in subcutaneous adipocytes from women with visceral obesity.