Switch that turns on our 'healthy' fat discovered by LUMC researchers
&w=710&h=710)
"When we are cold, our brain sends a signal to brown adipose tissue via nerves," explains Professor of Endocrinology Patrick Rensen. "This signal activates brown fat cells, which in turn burn sugar and fat molecules from the blood. This not only releases CO2 that is exhaled, but also heat that warms our bodies." Rensen and colleagues have now discovered which 'switch' on brown fat cells is turned on by the signal from the brain.
Activating brown fat as a treatment?
That is the beta-2 receptor, the researchers write in Cell Reports Medicine. "With this knowledge, we can make new stimulators that activate brown fat. This approach could theoretically fight type 2 diabetes and cardiovascular disease because activation of brown fat by cold not only reduces body fat, but also the amount of glucose and cholesterol in the blood," says Rensen.
Research in humans
Earlier, Rensen and colleagues showed that stimulation of the beta-3 receptor in mice activates brown fat, causing the mice not only to lose body fat but also to develop less arterial calcification. However, human brown fat cells were found to possess hardly any of this beta-3 receptor. But stimulation of the beta-2 receptor did seem to activate brown fat cells in the laboratory. Now the researchers have also demonstrated this in humans.
"We administered salbutamol to 10 volunteers. This is a specific simulator of the beta-2 receptor. It was found to greatly increase the uptake of radiolabelled sugar by brown fat, except when the receptor was blocked. We demonstrated this with PET-CT scans in collaboration with the Radiology Department," Rensen said.
Preventing side effects
Eventually, Rensen hopes to treat people at high risk of type 2 diabetes and/or cardiovascular disease with beta-2 receptor stimulators. But before getting there, the researchers still have a lot of work to do. Rensen: "The first step will be to find a substance that 'turns on' this receptor only on brown fat cells." This is because the beta-2 receptor is also found on other tissues in our body. " We must first find a way to direct such stimulators very specifically to brown fat. That way, we can prevent side effects of these stimulators elsewhere in the body."