GLP-1 drug exendin-4 suppresses appetite by inhibiting newly identified hunger neurons in the brainstem | Research

The takeaway

Exendin-4 inhibits orexigenic NPY neurons in the brainstem nucleus tractus solitarius via GABAb receptor-mediated presynaptic GABA release, and chemogenetic activation of these neurons blocks exendin-4's appetite-suppressing effect.

New brain target identified
Brainstem NPY neurons are a critical mediator of GLP-1 drug appetite suppression—their activation blocks exendin-4's effect entirely

What the researchers found

Exendin-4 inhibits NTS NPY neurons indirectly via GABAb receptors by augmenting presynaptic GABA release. Chemogenetic activation of NTS NPY neurons counteracted exendin-4 anorexia. Chemogenetic inhibition of NTS NPY neurons mimicked exendin-4 eating suppression.

Why it matters

Understanding exactly how GLP-1 drugs suppress appetite in the brain could lead to more targeted weight loss drugs with fewer side effects and help explain why some people respond better than others to GLP-1 therapy.

How the study worked

Ex vivo electrophysiological recordings from NTS NPY neurons, chemogenetic (DREADD) activation and inhibition experiments, food intake measurements in mice.

What this study cannot tell us

Mouse study—circuits may differ in humans. Ex vivo recordings may not fully replicate in vivo physiology. Only exendin-4 tested; other GLP-1 agonists may differ. Chemogenetic tools have limitations.

How to read the evidence

Rigorous preclinical neuroscience study with electrophysiology and chemogenetics. Strong mechanistic evidence in mice but human translation uncertain.

When this study was published

Published in 2025; identifies a novel neural mechanism for GLP-1 appetite suppression.

The bigger picture

While hypothalamic appetite circuits are well-studied, this work highlights the brainstem NTS as an equally important target for GLP-1 drugs. Understanding both brain regions may explain the remarkable appetite-suppressing efficacy of these medications.

Questions still open

Do semaglutide and tirzepatide act on the same NTS NPY neurons?
Could targeting NTS NPY neurons directly produce weight loss without GI side effects?
Do individual variations in NTS NPY neuron density predict GLP-1 drug response?

Common questions

How do GLP-1 drugs reduce appetite in the brain?

This study found that exendin-4 (a GLP-1 drug) works partly by silencing specific hunger neurons (NPY neurons) in the brainstem. It does this indirectly by increasing the release of an inhibitory signal (GABA) from nearby neurons, effectively turning off the hunger drive.

Could this lead to better weight loss drugs?

Potentially. If drugs could directly target these brainstem NPY neurons without affecting the gut, they might suppress appetite without the nausea and vomiting that limit current GLP-1 drugs. This study provides a specific neural target for that approach.

Read the original research

GLP-1 receptor agonist exendin-4 suppresses food intake by inhibiting hindbrain orexigenic NPY neurons.

American journal of physiology. Endocrinology and metabolism, 328(5), E661-E674

View on PubMed ↗Publisher’s paper ↗

Citation

Shen, Jiayi; Wang, Mengtian; Pang, Guodong; Zhang, Yan; Zhang, Jian; Shi, Yuyan; Liu, Ji; Zhan, Cheng. (2025). GLP-1 receptor agonist exendin-4 suppresses food intake by inhibiting hindbrain orexigenic NPY neurons.. American journal of physiology. Endocrinology and metabolism, 328(5), E661-E674. https://doi.org/10.1152/ajpendo.00528.2024