An experimental drug causes loss of weight and fat
in mice, a new study presented at the Endocrine
Society’s 97th annual meeting in San Diego has
found.
Known as GC-1, the drug reportedly speeds up
metabolism, or burning off, of fat cells.
“GC-1 dramatically increases the metabolic rate,
essentially converting white fat, which stores
excess calories and is associated with obesity and
metabolic disease, into a fat like calorie-burning
brown fat,” said study author Kevin Phillips, PhD, a
researcher at Houston Methodist Research Institute,
Houston.
Until several years ago, scientists thought that
only animals and human infants have energy-burning,
“good” brown fat.
“It is now clear,” Phillips said, “that human adults
do have brown fat, but appear to lose its
calorie-burning activity over time.”
White adipose tissue, or fat, becomes a “metabolic
villain,” as Phillips called it, when the body has
too much of it. Some published research shows that
people who have more brown fat have a reduced risk
of obesity and diabetes. Researchers are now working
on ways to “brown” white fat, or convert it into
brown fat.
GC-1 works, according to Phillips, by activating the
receptors for thyroid hormone, which play a role in
regulating metabolism—the body’s conversion of food
into energy. Thyroid hormone receptors also help
with adaptive thermogenesis, in which the body
converts excess energy (calories and fat) to heat.
The roles that white fat and brown fat play in
metabolism is well documented, but new research
published in the January 2015 issue of the FASEB
Journal presents a new wrinkle: each type of fat may
change into the other, depending on the temperature.
In particular, cold temperatures may encourage
"unhealthy" white fat to change into "healthy" brown
fat.
Phillips said he and other researchers at Houston
Methodist Research Institute have tested the drug in
hundreds of mice, with partial research funding from
the National Institutes of Health. Obese mice, both
genetically obese and those with diet-induced
obesity, received GC-1 treatment daily.
Genetically obese mice lost weight and more than 50
percent of their fat mass in approximately two
weeks, Phillips reported. Treated mice also showed
antidiabetic effects, such as a sixfold improvement
or better in insulin sensitivity (how well the body
clears glucose from the bloodstream). He said mice
with diet-induced obesity experienced similar
improvements.
The drug also induced adaptive thermogenesis in fat
cells isolated from mice. Cells grown in culture in
a dish, as well as tissue samples taken from obese
mice, showed evidence of white-fat browning.
“Our data demonstrate that GC-1 is a novel
fat-browning agent that may have use in the
treatment of obesity and metabolic disease,”
Phillips said.
The drug has not yet undergone testing for weight
loss in humans. GC-1 is being tested in clinical
trials for lowering cholesterol, under the name
sobetirome. However, Phillips said the doses of
sobetirome used in the cholesterol-lowering studies
are much lower than what would be needed for weight
loss.
See also
Exposure to cold reveals the switch that controls
the formation of brown and white fat (2015-01-16)
Cool Temperature Alters Human Fat and Metabolism
(2014-07-30)
Researchers Determine Hormone Linked to Improved
Glucose Metabolism Activates Browning of Fat
(2014-01-27)
Fighting Obesity: New Hopes From Brown Fat
(2013-11-15)
Team finds mechanism that regulates production of
energy-burning brown fat (2013-03-19)
Newly isolated 'beige fat' cells could help fight
obesity (16/07/2012)
Turning 'bad' fat into 'good': A future treatment
for obesity? (04/05/2011)
Rising indoor winter temperatures linked to obesity?
(26/01/2011)
For more information
Endocrine Society
Endocrinology
The thyroid hormone receptor-beta-selective agonist
GC-1 differentially affects plasma lipids and
cardiac activity.
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