A few years ago, scientists discovered the liver releases a hormone to suppress consumption of sweet-tasting food once a person has consumed high volumes of sugar. New research, led by the University of Iowa, has now homed in on exactly how this mechanism works, and where in the brain it takes place.
Fibroblast growth factor 21 (FGF21) is a liver-derived hormone with a number of metabolic functions, including regulating acute insulin sensitivity. One of its more interesting roles is how it influences our preference for consuming sugary food.
Prior research has revealed when we eat a meal low in protein and high in carbohydrate our liver increases expression of FGF21. One of the roles of this hormone is to travel to brain and stop us eating more sugary food to avoid greater metabolic stress and protect the body from subsequent problems such as obesity and diabetes. This new study offers the first detailed insight into exactly where in the brain this hormone acts to modulate our preference for sugary food.
"This is the first study that's really identified where this hormone is acting in the brain and that has provided some very cool insights to how it's regulating sugar intake," says Matthew Potthoff, who led the new research.
Across a number of detailed mouse experiments the researchers discovered FGF21 crosses the blood-brain barrier and directly acts on specific glutamatergic neurons located in the ventromedial hypothalamus. By amplifying the sensitivity of these neurons to glucose, the mechanism is designed to lower a person’s sugar intake.
This particular mechanism was revealed to be highly specific in its downstream effects. FGF21’s actions in the ventromedial hypothalamus have no influence on overall caloric intake or energy expenditure, so it seems this process is solely working to slow, or stop, an organism eating high-sugar foods.
The researchers suggest this mechanism is just one of many liver-brain hormonal communications that organisms use to regulate nutritional intake. It’s hypothesized these mechanisms evolved to help direct organisms away from foraging foods containing macronutrients they do not need.
The discovery offers compelling future research pathways looking at whether drugs targeting this mechanism could be developed to specifically help control a person’s sugar intake. The study does note there are drugs being tested to treat diabetes and obesity that are modified forms of FGF21, but this study suggests incredibly precise targeting of this particular brain region could be useful in specifically regulating a person's sugar intake.
The new study was published in the journal Cell Metabolism.