Adipose tissue lipid mobilisation during exercise

Current knowledge. - In mammals, white adipose tissue is considered a quasi-unlimited energy storage depot. Under conditions of increased energy demand (fasting, exercise), adipose tissue triglycerides are hydrolyzed and released in the bloodstream as fatty acids (FA). Their uptake and subsequent oxidation in other tissues, mainly skeletal muscle generates energy to meet increased demand. In human adipose tissue, FA storage as triglycerides is partially regulated by the insulin hormone, while triglyceride hydrolysis is governed by catecholamines. Catecholamine action (epinephrine and norepinephrine) on lipolysis is the result of an equilibrium between stimulating beta-adrenergic ((1 and (2) and inhibitory alpha2-adrenergic agonists. In addition, recent findings demonstrate the importance of the atrial natriuretic peptide (ANP) pathway in triglyceride mobilization; ANP having a stronger lipolytic action than beta-adrenergic agonists. Herein, the pathways and regulatory mechanisms involved in adipose tissue lipid mobilization are discussed. The influence of factors, such as type and duration of exercise, subject gender, nutritional status and adiposity are examined. Future prospects. - Understanding the importance and influence of these factors on hormonal status, and hence triglyceride mobilization, is required to appropriately apply exercise regimes, in prevention and treatment of metabolic syndrome. (D 2007 Elsevier Masson SAS. Tons droits reserves.