Endocrine Abstracts

In rodents, brown adipose tissue is known to be a metabolically highly active organ. This concerns rates of blood flow, capacity for oxygen consumption and rates of uptake of lipid and carbohydrate substrates. The high rates of metabolism are dependent on stimulation of the tissue by norepinephrine, released from sympathetic neurons innervating the tissue. Following stimulation, thermogenesis occurs as a result of activation of the uncoupling protein UCP1 in the inner membrane of the numerous mitochondria. UCP1 is found only in brown adipocytes and in adipocytes with brown-like features, called brite (brown-like in white) or beige adipocytes, dispersed in several white adipose depots. Although the brite adipocytes appear attractive candidates to promote energy utilization and thus potentially weight loss, their natural abundance is markedly lower than that of classical brown adipocytes. The ability of brown adipose tissue to modulate body weight through UCP1-mediated thermogenesis, to dispose of whole body glucose and to clear triglycerides from the blood means that it has a capacity to improve many aspects of the metabolic syndrome. The confirmation of its activity in adult humans means that it is an interesting candidate for therapeutic development.