Scientists spot brain cells that trigger sugar cravings in humans

In what could control an unchecked sweet tooth in some people that leads to diabetes and obesity, new research has identified specific brain cells that control how much sugar you eat and how much you crave sweet-tasting food.

The new study focused on the actions of a hormone called fibroblast growth factor 21 (FGF21). This hormone is known to play a role in energy balance, body weight control, and insulin sensitivity.

The research team from the University of Iowa in the US and the University of Copenhagen in Denmark has shown, for the first time, which brain cells respond to FGF21's signals and how that interaction helps regulate the sugar intake and sweet taste preference.

The study, published in the journal Cell Metabolism, also revealed how the hormone mediates its effects.

"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," said Matthew Potthoff, associate professor of neuroscience and pharmacology in the University of Iowa Carver College of Medicine.

Understanding the biological mechanisms that control sugar intake and preference for sweet taste could have important implications for managing and preventing these health problems.

Although it was known that FGF21 acted in the brain, identifying the exact cellular targets was complicated by the fact that the hormone's receptor is expressed at very low levels and is therefore difficult to "see."

Using various techniques, the researchers were able to precisely identify which cells express the receptor for FGF21.

By investigating these cells, the study shows that FGF21 targets "glutamatergic" neurons in the brain to lower sugar intake and sweet taste preference.

The researchers also showed that FGF21's action on specific neurons in the ventromedial hypothalamus reduce sugar intake by enhancing the neurons' sensitivity to glucose.

Several drugs based on a modified form of FGF21 are already being tested as treatments for obesity and diabetes.

The new findings could potentially lead to new drugs that more precisely target the different behaviors controlled by FGF21, which might help to control how much sugar a person eats, the authors said..