Some Gut-Brain Nerve Cells Can Detect GLP-1, CCK, and PYY All at Once — and They Monitor Your Entire Digestive Tract | Research

The takeaway

A population of vagal nerve cells in mice co-expresses receptors for three major gut hormones (GLP-1, CCK, and PYY) and sends signals from the entire gastrointestinal tract to the brain.

3 receptors, 1 neuron
Individual vagal nerve cells co-express GLP-1, CCK, and PYY receptors and innervate both the stomach and colon

What the researchers found

Using RNAscope combined with immunohistochemistry, the researchers found that most GLP-1 receptor (GLP1R), cholecystokinin A receptor (CCKAR), and neuropeptide Y2 receptor (NPY2R) neurons in the nodose ganglia co-expressed all three receptors. These triple-positive neurons were preferentially located in the right nodose ganglion.

Dual retrograde labeling with distinct tracers confirmed that neurons co-expressing GLP1R, CCKAR, and NPY2R innervated both the stomach and the distal colon — meaning individual nerve cells sample chemical signals from the entire gastrointestinal tract. Additional receptor subtypes (NTSR1, GPR65, 5-HT3A) showed different distribution patterns, with NTSR1 and GPR65 neurons nearly always co-expressing both receptors.

Why it matters

GLP-1 drugs like semaglutide work partly through vagal nerve signaling, but exactly how the brain receives and integrates gut hormone signals has been unclear. This study shows that individual nerve cells can simultaneously detect multiple satiety hormones from different parts of the digestive tract. Understanding this integration could explain why combination gut hormone therapies (targeting GLP-1, CCK, or PYY together) may produce stronger appetite suppression than single-target drugs.

How the study worked

The study used mice (C57BL/6 strain) and combined RNAscope in situ hybridization with immunohistochemistry to map receptor expression in nodose ganglion neurons. Retrograde labeling with two distinct fluorescent tracers injected into different parts of the GI tract identified which neurons innervated which organs. This allowed the researchers to determine both receptor co-expression patterns and the anatomical reach of individual neurons.

What this study cannot tell us

This study was conducted entirely in mice, so the receptor co-expression patterns may not be identical in humans. The research mapped receptor expression but did not test functional responses — having a receptor present doesn't guarantee it's actively signaling. The study also could not determine whether these triple-receptor neurons change their expression patterns in obesity or after bariatric surgery.

How to read the evidence

This is a basic science study in mice using advanced molecular mapping techniques. It provides strong mechanistic evidence for receptor co-expression but has not been validated in humans or tested functionally.

When this study was published

Published in 2025, this is a very recent study reflecting state-of-the-art neuroscience mapping techniques applied to gut-brain signaling.

The bigger picture

The obesity drug field is moving toward multi-receptor agonists like tirzepatide (GLP-1 + GIP) and retatrutide (GLP-1 + GIP + glucagon). This study reveals that the vagal nerve system is already wired for multi-hormone integration — individual neurons can detect GLP-1, CCK, and PYY simultaneously. This natural co-expression pattern may explain why targeting multiple gut hormone pathways at once produces outsized weight loss effects, and it opens new questions about how mechanical stomach stretch signals combine with chemical hormone signals at the single-neuron level.

Questions still open

Do humans have the same triple-receptor neuron population in the nodose ganglion, and is it affected by obesity?
How do these co-expressing neurons prioritize signals when GLP-1, CCK, and PYY are all elevated simultaneously after a meal?
Could targeting the right nodose ganglion specifically enhance the appetite-suppressing effects of GLP-1 drugs?

Common questions

What does it mean that these neurons co-express three receptors?

It means a single nerve cell has the molecular machinery to detect three different gut hormones (GLP-1, CCK, and PYY) at the same time. Instead of separate nerve cells each monitoring one hormone, one neuron can integrate multiple satiety signals before sending a combined message to the brain.

Does this explain why GLP-1 drugs like Ozempic reduce appetite?

Partly. GLP-1 drugs activate GLP-1 receptors on vagal neurons, which signal the brain to reduce hunger. This study shows those same neurons also carry CCK and PYY receptors, suggesting the appetite-suppressing effect may involve cross-talk between multiple hormone pathways — not just GLP-1 alone.

Read the original research

Neurons Co-Expressing GLP-1, CCK, and PYY Receptors Particularly in Right Nodose Ganglion and Innervating Entire GI Tract in Mice.

International journal of molecular sciences, 26(5)

View on PubMed ↗Publisher’s paper ↗

Citation

Lansbury, Elizabeth Laura; Vana, Vasiliki; Lund, Mari Lilith; Ludwig, Mette Q; Mamedova, Esmira; Gautron, Laurent; Arnold, Myrtha; Egerod, Kristoffer Lihme; Kuhre, Rune Ehrenreich; Holst, Jens Juul; Rekling, Jens; Schwartz, Thue W; Pankratova, Stanislava; Dmytriyeva, Oksana. (2025). Neurons Co-Expressing GLP-1, CCK, and PYY Receptors Particularly in Right Nodose Ganglion and Innervating Entire GI Tract in Mice.. International journal of molecular sciences, 26(5). https://doi.org/10.3390/ijms26052053