Love handles, muffin tops and stomach tires white fat tissue forms the typical curves in the notorious problem areas to store energy. Exactly the opposite happens in brown fat tissue: Instead of being stored, energy gets transformed into heat. To the dismay of many people, adults have only small amounts of this energy burner. By contrast, babies and animals in hibernation have lots of it in their bodies where it serves for heat regulation.
Researchers know that external influences can stimulate the production of brown fat tissue in animals. If rodents are kept at low temperatures, clusters of brown fat cells form amid the white fat tissue. A DKFZ research team headed by Dr. Stephan Herzig, jointly with colleagues from Munich, Marburg, Frankfurt and Lausanne, has investigated the molecular causes of this phenomenon. They discovered that the production of the COX-2 inflammation enzyme is increased in white fat tissue of mice after exposure to cold temperatures. COX-2 is well known to scientists: It regulates the key step in the biosynthesis of prostaglandins inflammation-promoting hormones which are also responsible for activating pain.
"Our recent results prove that COX-2 and prostaglandins are crucial for the formation of new brown fat tissue and, thus, also for regulating body weight," said Stephan Herzig summarizing his data. Parallel to the increase in COX-2 production in white fat tissue, there is also a rising level of the protein which biochemically transforms energy into heat and is therefore considered the most important biomarker for brown fat cells. When the investigators switched off COX-2 in the white fat tissue, however, the typical appearance of brown fat cells could no longer be stimulated by the cold.
Even without using cold temperatures the scientists were able to stimulate the formation of brown fat cell clusters in white fat tissue by boosting the COX-2 production in mice using a molecular-biological trick. The
|Contact: Dr. Sibylle Kohlstdt|
Helmholtz Association of German Research Centres