Discovery of neurons responsible for appetite 🧠

Researchers have identified a group of brain cells in mice that play a key role in regulating appetite. These neurons, located in an ancient region of the brain, could pave the way for new approaches to treating obesity.

This discovery, published in the journal Cell, sheds light on a complex brain mechanism that integrates multiple food-related signals. Scientists used innovative techniques to study these neurons, which may also be present in humans.

A discovery in the brainstem

The identified neurons produce a hormone called cholecystokinin (CCK), known for its role in appetite regulation. Located in the dorsal raphe, an area of the brainstem, these cells respond to various stimuli, such as smell, taste, and the sensation of food in the stomach.

Using optogenetics, researchers activated these neurons in mice, which led to a slowing and then a cessation of food intake. The more intense the activation, the faster the mice stopped eating.

A link with current treatments

These neurons also respond to GLP-1 receptor agonists, medications used to treat obesity and type 2 diabetes. This similarity suggests that these cells could be targeted to improve existing treatments.

Researchers believe that modulating the activity of these neurons could help control eating habits in overweight individuals. This approach could complement current GLP-1-based therapies.

Potential implications for humans

Although this research was conducted on mice, the location of these neurons in the brainstem, a region conserved in all vertebrates, suggests they may also exist in humans.

This discovery opens new perspectives for understanding the mechanisms of satiety. It could also lead to more targeted treatments for combating obesity, a global health issue affecting over a billion people.

To go further: How does the brainstem influence appetite?

The brainstem is an ancient brain structure that regulates vital functions such as breathing and digestion. It receives signals from the stomach and intestines to adjust appetite in real-time, independently of brain regions involved in conscious decisions.

Studies show that certain brainstem cells react immediately to ingested nutrients. They can trigger a sensation of satiety even before food is fully digested, helping to limit overeating and maintain energy balance.

In humans, a dysfunction in these mechanisms could promote excessive or insufficient eating behaviors. Understanding the precise role of the brainstem could enable the development of targeted treatments for obesity and other metabolic disorders.

What is optogenetics and how is it used in neuroscience?

Optogenetics is a technique that allows neurons to be activated or inhibited using light. Light-sensitive proteins, called opsins, are introduced into brain cells, making their activity controllable by light pulses.

In the study on appetite regulation, optogenetics enabled the specific activation of neurons producing cholecystokinin. This stimulation led to a rapid cessation of food intake, confirming their central role in the sensation of satiety.

This method offers precise and reversible control of neuronal activity, unlike chemical or electrical techniques. It is widely used to explore brain circuits involved in complex functions such as appetite, memory, or emotions.