A team of scientists recently discovered a hormone that controls fat burning in animals. Previous research had showed links between the neurotransmitter serotonin and weight loss but the actual mechanisms were unknown. Now, researchers have found a hormone that plays an even larger role. The details are in a paper that was just published in the journal Nature Communications.
Scientists have long known that the neurotransmitter serotonin aids in fat burning and other metabolic processes. Oddly, researchers had struggled to figure out the mechanisms behind this function. The factors that triggered this action were completely unknown—serotonin is a multi-function neurotransmitter that only sometimes encourages fat burning.
Researchers from The Scripps Research Institute studied roundworms (Caenorhabditis elegans), simple organisms that share some aspects of their nervous system, including serotonin production, with humans. Roundworms are commonly used in research because they are the simplest organism with a complete nervous system. The worms are also transparent, making them easy to study without needing to dissect them. The research team deleted genes to see if any of them would change serotonin production, potentially preventing or increasing fat loss.
After deleting gene after gene, the team finally found one that disrupted serotonin signaling. The gene coded for a newly-discovered hormone called FLP-7. Mammals have a similar version of FLP-7 but the hormone had never been studied extensively. The team dyed FLP-7 molecules with fluorescent red protein, allowing them to track its movement throughout the worm’s body. The researchers found that it was produced when there were high levels of serotonin in the brain. Once activated, FLP-7 kick started fat-burning mechanisms, regardless of food consumption or fat content. When not modified, FLP-7 is naturally produced when the brain sends signals based on food availability. FLP-7 then initiates fat burning in intestinal cells. When the researchers increased FLP-7 without affecting serotonin levels, the worms still burned fat while otherwise functioning normally.
The findings show that there is a specific hormone involved in fat burning, called FLP-7. Although the hormone is activated as serotonin levels rise, it can be increased on its own to cause weight loss without other side effects. This information may help researchers develop new weight loss products.
Palamiuc et al. A tachykinin-like neuroendocrine signalling axis couples central serotonin action and nutrient sensing with peripheral lipid metabolism. Nature Communications (2017).