Newswise — Scientists say they know how white adipose cells -- often called "bad fat" -- can be converted into "good," brown adipose in mice using little more than a synthetic stand-in for thyroid hormone.

Preliminary data presented by Houston Methodist metabolic disease expert Kevin Phillips, Ph.D., at the Endocrine Society's annual meeting in San Diego suggests GC-1, a pharmacological thyroid hormone mimic, is enough to transform obesity-associated white adipose into the brown cells that readily burn fat.

The binding of GC-1 by thyroid hormone receptors in white cells' nuclei is followed by dramatic changes in gene expression patterns and ultimately, cell metabolism. Phillips says the introduction of GC-1 to a genetically obese mouse model increased the mice's mean metabolic rate 60 percent and their average body temperature 3.8 deg C (ca. 7 deg F). Accompanying this "browning" of their white adipose, the mice lost weight regardless of whether they continued to eat, and the weight loss was attributed to the loss of total adipose mass. The researchers saw similar results in mice that were obese because of diet and not genes. Following the conversion of white adipose to brown, previously insulin-insensitive obese mice were found to be sensitive to the hormone once again. GC-1 is an investigative tool that is similar to thyroid hormone but achieves more dramatic effects when bound by thyroid hormone receptor.

"It is not clear if the browning of white fat is something that could be achieved with the body's natural thyroid hormone alone, but it is looking likely we may be able to achieve the effect with a drug," Phillips said. "I do expect it may be a decade before such a drug exists -- with drugs for metabolic diseases like obesity and diabetes, we need to be extremely careful about making sure they are safe for patients."

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Session: OR23-Thyroid Hormone Action, Cancer and Clinical Thyroid Translational Friday, March 6, 2015: 11:30 AM-1:00 PMPresentation Start Time: 12:15 PMRoom 6B (San Diego Convention Center)

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