Activating brown fat receptors helps mice burn fat, build muscle
Researchers have found a way to reverse some signs of aging in mice. By triggering receptors on a fast-burning form of fat, the team was able to give older animals less fat and more muscle, making them as healthy as much younger mice. And better yet, humans seem to have a similar pathway.
Not all fat is created equal. White fat is the stuff we’re constantly battling around our bellies and thighs, which the body packs on to store excess energy. But brown fat is a more beneficial version, which the body burns away easily to produce energy and heat.
As such, researchers have been studying brown fat for years, looking for ways to increase its levels or convert white fat to brown. And now, the researchers on the new study have found a way to ramp up its benefits.
Receptors are small “antenna-like” structures on the surface of cells, which receive molecular signals to trigger changes in the cell. Brown fat is known to have high numbers of A2B receptors, and the team investigated why that might be the case.
"In our publication we took a closer look at the A2B receptors in brown adipose tissue," says Alexander Pfeifer, a lead author of the study. "In the course of this we discovered an interesting association: The more A2B a mouse produces, the more heat it generates."
This suggests that the A2B receptors are increasing the activity of the brown fat. The researchers tested the idea by giving older mice an agonist that activates the A2B receptor. Sure enough, they found that these mice burned more body fat.
But there was a secondary effect that was even stranger. The mice lost fat but not much weight, and the team soon realized that they were gaining muscle mass at the same time. On closer inspection it was discovered that muscle cells also have high numbers of these A2B receptors on their surface.
After four weeks of the treatment, the oxygen consumption of the mice had been boosted by almost 50 percent, and they were found to have about as much muscle mass as young mice. This suggests that A2B receptor agonists could be a useful treatment for reversing these products of aging.
But of course mice are very different to humans. So to check whether the results might carry across to us, the team then examined cultures of human cells and tissues. The same mechanism appeared to be at work here too.
Unfortunately, it still seems like this kind of research would be a long way off clinical use. The team notes that there’s no A2B activator yet approved for use in humans, so the side effects remain unknown.
The research was published in the journal Cell Metabolism.
Source: University of Bonn
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