Neuroendocrine and metabolic effects of adipocyte-derived hormones

Obesity is characterized by an increase in adipose tissue mass. Contrary to the previous view of adipose tissue as simply an inert tissue devoted to energy storage, studies over the past decade have shown that adipose tissue is actively involved in regulating physiological processes and participates in disease. Adipose tissue secretes factors that exert local and systemic effects. Leptin, pro-inflammatory cytokines, resistin and proteins involved in haemodynamic regulation and coagulation are increased in obesity while adiponectin is reduced. The production of active corticosteroids is also increased in obesity. There is now growing evidence that adipocyte secretory factors regulate energy homoeostasis, as well as cardiovascular and immune systems. Some adipocyte hormones, most notably leptin, act in the brain to influence the neuroendocrine axis and energy balance, whereas adiponectin and resistin exert opposing effects on glucose and lipids. Understanding the actions of adipocyte hormones will provide novel insights into the pathophysiology and treatment of obesity.