Abstract

Adipose tissue, once thought to function primarily as a passive depot for the storage of excess lipid, is now understood to play a much more active role in metabolic regulation, secreting a variety of proteins which are collectively known as adipocytokines. These include tumor necrosis factor-α (TNF-α), plasminogen activator inhibitor type 1 (PAI-1), leptin, resistin and adiponectin. Adiponectin, also referred to as AdipoQ, Acrp30, apMΙ or GBP28, is a novel adipose-specific protein which is derived only from adipose tissue and is abundantly present in circulating blood. A recent genome study mapped a susceptibility locus for type 2 diabetes mellitus and the metabolic syndrome on chromosome 3q27, where the adiponectin gene is located. Adiponectin receptors-1 (AdipoR1) and 2 (AdipoR2) are expressed ubiquitously in most organs especially in skeletal muscle, AdipoR1, and liver, AdipoR2. Adiponectin exerts a protective action in the initiation and progression of atherosclerosis through anti-inflammatory and anti-atherogenic effects. Adiponectin levels are decreased in patients with obesity, type 2 diabetes, essential hypertension and coronary artery disease (CAD). Adiponectin levels are also negatively correlated with the CRP levels in patients with CAD. Investigation of mechanisms explaining the relationship between adiponectin and insulin resistance suggest that this adipocytokine and TNF-α inhibit each others expression and production in adipocytes. Overall, adiponectin is an important molecular link between obesity, insulin resistance and atherogenesis and could become a promising target for future investigations into possible means of reduction of the morbidity and mortality of atherosclerotic disease.

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