Near the end of a holiday meal, cues from the stomach tell the brain that it’s time to stop eating. Gastrointestinal signals related to stomach expansion are relayed to a region of the brainstem known as the caudal nucleus of the solitary tract, or cNTS. Neurons within this region are thought to act as regulators that decide when enough food has been consumed and tell the body that it’s time to slow down or stop eating. However, these neurons have been difficult to study because the cNTS is located very deep within the brain.
This week in the journal Nature, a group of researchers used a new technique to record signals from individual neurons in the cNTS in mice. The observations were taken in real time, as the mice devoured a meal. The authors examined the activity of two groups of neurons in the cNTS that are known to be involved in regulating food intake. They found that the first group of neurons, called CGC cells, responded to mechanical stretch signals from the stomach and tracked the amount of food the mice consumed over tens of minutes. The activity pattern in the second group of neurons, called PRLH cells, was markedly different: during food consumption, PRLH activity tracked with taste signals originating from the mouth on a moment-to-moment basis. This unexpected finding suggests that the perception of food in both the mouth and the stomach help to set the pace of consumption.
Neurons in the cNTS produce an appetite-suppressing hormone called glucagon-like peptide-1. This hormone is mimicked by new appetite-suppression drugs like Ozempic and Wegovy. Gaining a better understanding of how ingestive signals are integrated in the brain may therefore improve the efficacy of future medications for weight loss.
This study was led by Zachary Knight, a Howard Hughes Medical Institute investigator at the University of California, San Francisco, and his PhD student, Truong Ly.
Managing Correspondent: Alexandra Hartman
Press Article: Feeling full? Researchers pinpoint neurons that prevent eating too much, too fast (Science News)
Original Journal Article: Sequential appetite suppression by oral and visceral feedback to the brainstem (Nature)
Image Credit: Pexels/Nicole Michalou