Activated Brown Fat Controls Obesity and Metabolic Disorders

Researchers speculate that the development of new drugs to activate human brown adipose tissue (BAT) could lead to safe treatments for obesity and metabolic disorders.

White adipose tissue (WAT) stores excess calories, while BAT consumes molecular fuel for thermogenesis (heat generation) using the tissue-specific enzyme UCP1(uncoupling protein 1).

Investigators at Harvard Medical School (Boston, MA, USA) delved into the genetic expression and protein activities found in BAT to determine its possible future role in the treatment of obesity. To this end, they isolated neck fat from adult human volunteers and compared its gene expression, differentiation capacity, basal oxygen consumption, and oxygen consumption rate (OCR), to different mouse adipose depots.

Among findings reported in the April 21, 2013, online edition of the journal Nature Medicine was that the OCR of the human BAT cells from the deep location in the neck next to the longus colli was nearly 50% of the rate found for mouse BAT cells. In contrast, the OCR of human WAT was only one-hundredth of the OCR found in the most active human BAT from the longus colli depot.

The investigators established a protocol for growth in culture of new functional BAT cells (adipocytes) by differentiating precursor cells (preadipocytes) derived from both superficial and deep human neck fat tissue. When stimulated, these cells expressed the same genes as naturally occurring brown fat cells. The use of brown fat cells produced in vitro will encourage development of drugs and other treatments that increase BAT activity for the correction of obesity and other metabolic disorders.

“BAT is most abundant in the deep locations of the neck, close to the sympathetic chain and the carotid arteries, where it likely helps to warm blood and raise body temperature,” said first author Dr. Aaron M. Cypess, assistant professor of medicine at Harvard Medical School. “Now that we know where brown fat is, we can easily collect more cells for further study.”

“Our research has significant practical applications. If we stimulate the growth of brown fat in people, it may burn their white fat and help them lose weight, which lessens insulin resistance and improves diabetes,” said Dr. Cypess.

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