The adipocyte as an endocrine cell

Adipocytes are now known to secrete peptides with a variety of effects, some of which can be defined as endocrine. According to a relatively strict definition of an endocrine cell, there is now proof that adipocytes function as endocrine cells in humans with respect to leptin, the best-characterized adipocyte hormone. Establishing that other adipocyte secretory products are truly endocrine molecules has not been as straightforward, however. Experiments in animal models have demonstrated that the hormones and cytokines produced by adipocytes have actions in the central nervous system, liver, muscle, and bone as well as a variety of other tissues. This review examines these data but attempts to emphasize what is known about the role of human adipose tissue. The secretion and effects of leptin, adiponectin, angiotensinogen, resistin, tumor necrosis factor-α, interleukin-6, acylation stimulating protein, and plasminogen activator inhibitor-1 are described.