Nutritional regulation of leptin signaling.

The adipose-derived hormone leptin was first described as a satiety factor, but recent studies have demonstrated that leptin acts on various physiologic processes and plays an important role in obesity and the associated hypertension. In this article, we review recent data on leptin signaling as it relates to nutrition. Plasma leptin levels are positively correlated to body fat and adipocyte size and, therefore, levels are higher during obesity. The hyperphagia in the presence of hyperleptinemia in obesity is a paradoxical effect. Leptin signaling primarily depends on the leptin receptor (Ob-R). The suppressor of cytokine-signaling (SOCS) protein, in particular SOCS-3, was shown as a leptin-regulated inhibitor of proximal leptin signaling, although its role during obesity remains uncertain.