Some fat cells can feel the cold

July 2, 2013 by Marcia Malory report

(Medical Xpress)—To survive in cold environments, mammals burn fat to produce heat. The breakdown of fat helps prevent obesity and related metabolic diseases, such as diabetes. Bruce Spiegelman and his colleagues at Harvard Medical School studied how white, beige and brown fat cells respond to cold temperatures. They found that while all three types of fat cells respond to temperature changes when stimulated by certain brain chemicals, white and beige fat cells react to cold temperatures independently of the brain. Their research appears in the Proceedings of the National Academy of Sciences.

Mammals break down fat to produce energy, which enables them to maintain a constant body temperature in cold weather. Obesity can occur if fat does not break down and remains stored in the body.

There are three types of : brown, white and beige. The primary role of brown fat cells is to generate heat in newborns and hibernating mammals, which cannot shiver. Brown fat cells have small molecules and break down easily. While newborns have many of these cells, adult humans retain only a small amount in the interscapular region.

White fat cells store energy. They contain larger molecules than brown cells and do not break down as easily.

Beige cells, like , store energy. However, like brown cells, beige fat cells break down and generate heat in response to cold. Normally when peripheral body cells sense cold, they send this information to the hypothalamus, which then, via the (SNS), sends norepinephrine (NE) to brown and beige fat cells. The NE attaches to beta-adrenergic receptors in these cells. This causes the expression of genes for thermogenesis.

To study the influence of the brain on heat production, Spiegelman's team exposed mice lacking beta-adrenergic receptors to a temperature of 10 degrees Celsius for 20 hours. Thermogenic gene expression in brown fat was much lower in these mice than in controls. However, thermogenic gene expression in beige and white fat cells increased in both groups, suggesting that these cells, but not brown fat cells, react to cold even without the brain's influence.

The researchers then exposed in vitro fat cells to temperatures ranging from 27 to 33 degrees Celsius for four hours. While brown fat cells reacted to the cold only when NE was added, beige and white cells responded without the addition of NE, indicating once again that they do not require the influence of the brain to generate heat.

Previously, scientists thought fat cells only broke down when beta-adrenergic receptors received signals from the brain. Agonism of the beta-adrenergic system increases the expression of thermogenic genes. However, beta-adrenergic agonists affect many vital organ systems, so their potential for use in treating obesity and related disorders is limited. The discovery that some fat cells respond directly to cold could lead to the development of new treatments for these conditions.

Explore further: Newly isolated 'beige fat' cells could help fight obesity

More information: Fat cells directly sense temperature to activate thermogenesis, PNAS, Published online before print July 1, 2013, doi: 10.1073/pnas.1310261110

Abstract
Classic brown fat and inducible beige fat both dissipate chemical energy in the form of heat through the actions of mitochondrial uncoupling protein 1. This nonshivering thermogenesis is crucial for mammals as a defense against cold and obesity/diabetes. Cold is known to act indirectly through the sympathetic nervous systems and ?-adrenergic signaling, but here we report that cool temperature (27–33 °C) can directly activate a thermogenic gene program in adipocytes in a cell-autonomous manner. White and beige fat cells respond to cool temperatures, but classic brown fat cells do not. Importantly, this activation in isolated cells is independent of the canonical cAMP/Protein Kinase A/cAMP response element-binding protein pathway downstream of the ?-adrenergic receptors. These findings provide an unusual insight into the role of adipose tissues in thermoregulation, as well as an alternative way to target nonshivering thermogenesis for treatment of obesity and metabolic diseases.

Related Stories

Newly isolated 'beige fat' cells could help fight obesity

July 12, 2012
Scientists at Dana-Farber Cancer Institute have isolated a new type of energy-burning fat cell in adult humans which they say may have therapeutic potential for treating obesity.

Newly discovered human fat cell opens up new opportunities for future treatment of obesity

May 2, 2013
The body's brown fat cells play a key role in the development of obesity and diabetes. Researchers at Sahlgrenska Academy, University of Gothenburg, Sweden, have now discovered that we humans have two different kinds of brown ...

Scientists advance understanding of human brown adipose tissue and grow new cells (w/ Video)

April 22, 2013
Joslin scientists report significant findings about the location, genetic expression and function of human brown adipose tissue (BAT) and the generation of new BAT cells. These findings, which appear in the April 2013 issue ...

Brown fat responsible for from heart disease-related deaths in winter

July 2, 2013
More people die from heart-disease during the winter months, and according to a new study published in the journal Cell Metabolism, the increase in mortality is possibly due to the accelerated growth of atherosclerotic plaque ...

How 'beige' fat makes the pounds melt away

August 28, 2012
Researchers from the University of Bonn and the Max Planck Institute of Biochemistry in Martinsried have decoded a signal path that could boost the burning of body fat. Mice that are missing a signal switch called VASP are ...

Recommended for you

Study confirms link between the number of older brothers and increased odds of being homosexual

December 12, 2017
Groundbreaking research led by a team from Brock University has further confirmed that sexual orientation for men is likely determined in the womb.

Time of day affects severity of autoimmune disease

December 12, 2017
Insights into how the body clock and time of day influence immune responses are revealed today in a study published in leading international journal Nature Communications. Understanding the effect of the interplay between ...

Team identifies DNA element that may cause rare movement disorder

December 11, 2017
A team of Massachusetts General Hospital (MGH) researchers has identified a specific genetic change that may be the cause of a rare but severe neurological disorder called X-linked dystonia parkinsonism (XDP). Occurring only ...

Protein Daple coordinates single-cell and organ-wide directionality in the inner ear

December 11, 2017
Humans inherited the capacity to hear sounds thanks to structures that evolved millions of years ago. Sensory "hair cells" in the inner ear have the amazing ability to convert sound waves into electrical signals and transmit ...

Gene therapy improves immunity in babies with 'bubble boy' disease

December 9, 2017
Early evidence suggests that gene therapy developed at St. Jude Children's Research Hospital will lead to broad protection for infants with the devastating immune disorder X-linked severe combined immunodeficiency disorder. ...

In lab research, scientists slow progression of a fatal form of muscular dystrophy

December 8, 2017
In a paper published in the Nature journal Scientific Reports, Saint Louis University (SLU) researchers report that a new drug reduces fibrosis (scarring) and prevents loss of muscle function in an animal model of Duchenne ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

wjkeith87
not rated yet Jul 03, 2013
33 C is 91.4 F am I missing something, because that isn't very cool.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.