|
No longer viewed as inert packets of energy, fat cells are two-faced masterminds of metabolism.
Kendall Powell weighs up the differences between ‘fat’ fat cells and thin ones.
Unwanted, unloved, yet often overabundant,few have much regard for fat. Scientists, too, long thought of fat cells as good-for-nothing layabouts unworthy of attention; containers stuffed with energy to be released at the body’s command.So stuffed, in fact, that many other parts of the cell were thought too squeezed to function.
So when, in the early 1990s, graduate student G鰇han Hotamisligil at Harvard Medical School in Boston caught fat tissue doing something biologically remarkable, at first he did not believe his own data. He repeated the work many times, but it always came out the same: fat from obese mice was producing TNFα — the hot inflammatory molecule of the day because of its role in autoimm-une disorders such as arthritis. After he and his colleagues published their observation in Science1,others in the field remaned sceptical. Hotamisligil says he was invited to speak at meetings “for entertainment purposes”
Since then, fat cells have had an image change. This started with the 1995 discovery that fat secretes leptin, a hormone that tells the brain “I’m full, stop eating”. In retrospect, it makes sense that fat should tell the body how much energy it is storing and how much more to take in. But when it came to obesity-related problems such as type 2 diabetes and cardiovascular disease, fat was still not seen as an active player. These conditions were thought to be caused by an excess of nutrients from overeating, or a glut of fatty molecules spilling out of storage into the bloodstream.
More than a decade on, fat has a higher status.Scientists know that fat cells pump out ten or more molecules called adipokines that carry messages to the rest of the body. And ‘fat’ fat cells — those common in the obese and which are themselves bloated with lipids — send different
molecular messages from ‘thin’ fat cells.
The signals from ‘fat’ fat are thought to directly promote insulin resistance and to trigger inflam -mation, which may, in turn,cause type 2 diabetes, cardiovascular disease,increased cancer risk and other obesityassociated problems. This means that it might be possible to treat these conditi-o ns without shedding the fat itself. Some remedies might be as simple as using anti-inflammato-r y drugs that have been around for more than a century;others might involve persuading obese fat cellsto behave like skinny ones.
.............
http://www.daydownload.com/hosting.php?ref=dycQdEEMiilA |
|