Researchers from the University Hospital Bonn have reported that adenosine may stimulate brown fat to burn off undesirable white fat cells.
The team, led by Prof. Alexander Pfeifer from the hospital's Institute of Pharmacology and Toxicology, published their findings on Oct. 15, 2015 in Nature. According to Pfeifer, humans have white and brown fat cells, the former leading to undesirable fat accumulation, while the latter convert excess energy into heat.
The group worked with an international team from Sweden, Denmark and Finland, as well as from the Helmholtz-Center Dresden-Rossendorf and the University of Düsseldorf to discover a new signalling molecule capable of activating brown fat cells: adenosine.
Adenosine is typically released during stress. Crucial for transmitting the adenosine signal is the adenosine receptor A2A. Although it was previously thought impossible for adenosine to activate brown fat, it binding to the A2A receptor in brown fat cells significantly stimulates fat burning. Using brown fat cells removed from humans during surgery, the scientists investigated the signaling pathway for fat activation using adenosine. The scientists choose to not use rats or hamsters, where adenosine blocks brown fat. Conversely, mice and humans have a similar reaction to adenosine.
In addition, the research team investigated the possibility that adenosine transforms white fat cells into brown fat cells–a process termed “browning.” White fat cells normally cannot be induced to burn excess fat by adenosine, as they simply lack the A2A receptor. For this reason, the team of scientists transferred the A2A receptor gene from brown fat cells to white fat cells in mice. Consequently, the white fat cells also have A2A receptors and start browning and burning energy.
The researchers still have many questions, and clinical application will be conducted in the future. The researchers also did not mention investigating other routes of adenosine administration, such as topical.