ABSTRACT
Excess energy is stored in adipose tissues in the form of triglycerides (TGs), which are hydrolyzed to free fatty acids(FFAs) to meet energy requirement under fasting conditions. In addition to thermogenesis and organ protection,the adipose tissue is now recognized as an important endocrine organ. The proteins secreted by adipocytes are termed as adipokines. Adipokines appear to be involved in such cellular processes as energy intake and energy expenditure,glucose and lipid metabolism,as well as anti- and pro-inflammatory effects via autocrine, paracrine and endocrine. At the systemic level, adipokines regulate various biological processes in target organs,including the brain,liver,muscle,vasculature,heart and pancreas, immune system, and others. Adipokines exert specific effects on glucose and lipid metabolism, including glucose metabolism (leptin, adiponectin, resistin), insulin sensitivity [leptin, adiponectin,zinc-α2-glycoprotein(ZAG)],adipogenesis [bone morphogenetic protein 4 (BMP4)] and other biological processes. However,a linkage between adipose tissue dysfunction and metabolic disorders needs further clarification. Altered expression or secretion of adipokines under adipose tissue dysfunction may contribute to a spectrum of obesity-associated diseases. Preclinical and clinical studies show that activating or inhibiting the signaling of specific adipokines could be an approach suitable to metabolic disease intervention. The current article reviews the effects of some adipokines on metabolism in order to deepen our understanding of the adipokines function.