Recently Uncovered Brain Cells Track Eating and Signal When to Stop

Researchers at Columbia University have identified specific neurons in mouse brains that instruct these creatures to halt their eating.

While it’s known that various feeding circuits in the brain play a part in monitoring food consumption, the neurons in these circuits don’t actually make the final call to stop eating.

The newly discovered neurons, part of these circuits, are situated in the brainstem, which is the most primitive section of the vertebrate brain. This finding may pave the way for innovative obesity treatments.

“These neurons are different from other neurons linked to feeling full,” explains Alexander Nectow, a physician-scientist at Columbia University Vagelos College of Physicians and Surgeons, who conducted this research alongside Srikanta Chowdhury, a research associate in Nectow’s lab.

“Unlike other brain neurons that typically solely detect food in our mouths, how our stomach feels full, or the nutrients we receive from food, these neurons uniquely integrate various types of information and more.”

Neurons Found in the Brainstem

Deciding when to stop eating is a common experience. “Every time we have a meal, there comes a moment when we begin to feel satisfied, leading us to a point where we ultimately think, that’s enough,” says Nectow.

How does the brain determine when the body has had its fill, and what mechanism does it use to signal the end of a meal?

Previous studies had traced these decision-making neurons to the brainstem, but further exploration stopped there.

Utilizing new single-cell analysis techniques, Nectow and Chowdhury could investigate the brain region and differentiate between cell types that were previously hard to identify.

“This technique—spatially resolved molecular profiling—allows us to observe where the cells are in the brainstem and understand their molecular characteristics,” explains Nectow.

While examining a area of the brainstem known for processing intricate signals, researchers discovered previously unidentified cells resembling appetite-regulating neurons. “We were intrigued and asked, ‘What function do these neurons serve?’”

Neurons Monitor Each Bite

To understand the impact of these neurons on eating, the team modified them to be activated or deactivated with light.

When the neurons were activated by light, the mice consumed significantly smaller meals. The degree of activation influenced how quickly the mice ceased eating. “Interestingly, these neurons don’t just trigger an immediate stop; they assist the mice in reducing their eating tempo gradually,” adds Chowdhury.

Nectow and Chowdhury also examined how other eating circuits and hormones interacted with these neurons. They found that appetite-increasing hormones silenced the neurons, while a GLP-1 agonist, which is currently favored in treating obesity and diabetes, activated them. These findings indicated that these signals assisted the neurons in monitoring each bite the mice took.

“Essentially, these neurons can detect the presence of food, perceive it in the mouth and stomach, and interpret the gut hormones released during eating,” Nectow elaborates. “Ultimately, they utilize all this information to make the call on when it’s time to stop.”

Although these specialized neurons were studied in mice, Nectow suggests that their location in the brainstem—a structure fundamentally similar across all vertebrates—indicates that humans likely possess similar neurons.

“We believe this discovery provides critical insight into understanding the concept of feeling full, how it occurs, and how this perception is used to conclude a meal,” Nectow states. “We also hope it could pave the way for future obesity therapies.”