ABSTRACT
Th e identifi cation of the product of the gene obese threw light on the role of adipose tissue (AT) in the pathophysiology of obesity-related diseases. It has become increasingly evident that AT-derived cytokines mediate between obesity-related exogenous factors and the molecular events that lead to metabolic syndrome and infl ammatory and/or autoimmune conditions. Furthermore, adipokines aff ect various biological processes, including metabolism, satiety, infl ammation and cardiovascular function. Apelin is a 36 amino acid peptide identifi ed as the endogenous ligand of the orphan G protein-coupled receptor APJ. Apelin and APJ mRNA are widely expressed in several rat and human tissues and have functional eff ects in both the central nervous system and periphery. Th e cardiovascular system appears to be a privileged source of apelin, since both apelin and its receptor are present in the heart, large and small conduit vessels, and endothelial cells. Apelin and its receptors are involved in the regulation of cardiovascular function, central fl uid homeostasis, vessel formation and endothelial cell proliferation. Currently, roles have been established for the apelin system in lowering blood pressure, as a potent cardiac inotrope, in modulating pituitary hormone release and food intake, in stress activation, and as a novel adipokine that is excreted from fat cells and regulates insulin. Given its broad array of physiological roles, apelin has attracted much interest as a target for novel therapeutic approach and drug design.
