Under normal physiological conditions, fat cells store energy. In the cells of brown adipose tissue, or fat, however, energy is dissipated in the form of heat: the brown fat thus acts as a biological heater. Most mammals have this mechanism. In humans it keeps infants warm, in adults brown fat activation is positively correlated with cardio-metabolic health.
"Nowadays, however, we are warm even in winter. This is why the" ovens "we have in our body are hardly needed anymore," explains Prof. Dr. Alexander Pfeifer of the Institute of Pharmacology and Toxicology of the University of Bonn. At least funtil next winter, I say. At the same time, we eat an increasingly energy-rich diet and move much less than our ancestors. These three factors are poison to brown fat cells: They gradually cease to function and eventually die. On the other hand, the number of severely overweight people in the world continues to increase. "Research groups around the world are looking for fat-burning substances that stimulate brown fat," explains Pfeifer.
News from brown fat
The team of researchers from the University of Bonn recently identified a hitherto unobserved function of a well-known molecule, inosine, which is said to be an effective fat burner.
'Dying cells are known to release a series of messenger molecules that affect the function of neighboring cells,' explains Dr Birte Niemann of Pfeifer's research group. "We wanted to know if this mechanism also exists in brown fat."
For this study, the researchers looked at the brown fat cells under severe stress, so that the cells were practically dying. "We found that they secrete purine inosine in large quantities, "says Niemann. More interesting, however, was how intact brown fat cells responded to the call for molecular help: they were activated by inosine (or simply by dying cells in their vicinity). The inosine then ignited the furnace inside them. The white fat cells also converted to their brown brothers. The mice fed a high-energy diet and treated with inosine at the same time remained leaner than the control animals. and were protected from diabetes.
Okay, it burns fat in mice… And in humans?
"There is a drug developed for coagulation disorders, but it also inhibits the inosine transporter," explains Pfeifer, who is also a member of the transdisciplinary research areas "Life and Health" and "Sustainable Futures" of the University of Bonn. "We fed this fat-burning drug to the mice and they consumed more energy as a result."
And U.S? Interestingly, humans also have an inosine transporter. And in 2-4% of people it is less active due to a genetic variation.
"Our colleagues from the University of Leipzig genetically analyzed 900 individuals," explains Pfeifer. "The subjects with the least active transporter were on average significantly leaner." These results suggest that inosine also regulates thermogenesis in human brown fat cells. Substances that interfere with the transporter activity may therefore be suitable for the treatment of obesity. The drug already approved for bleeding disorders could serve as a starting point for a new fat-burning drug.
Obviously, even if the drug is already used for other purposes, further human studies are needed to clarify the pharmacological potential of this mechanism. It is clear, however, that a pill alone cannot be the solution to the rampant obesity pandemic in the world and the scientific community agrees on this. Similar evaluations have also been made with the recent discovery of a possible "exercise pill"which in the future could completely supplant physical activity.
The available therapies are not effective enough at the moment. There are also subjects who do not have a "normal" weight imbalance, and need concrete support in diet and exercise: investigating the role of inosine is welcome.