Popular medicines for weight loss and diabetes, like semaglutide and Ozempic, belong to a group called GLP‑1 drugs. A new study funded by the National Institutes of Health (NIH) discovered a surprising way that some newer oral GLP‑1 pills affect the brain.
Oral GLP‑1 Pills Reduce Eating for Fun
In experiments with mice, the pills made the animals eat less for pleasure. The researchers found the drugs changed activity in a reward circuit deep inside the brain.
This brain pathway is different from the appetite‑control centers that older injectable GLP‑1 drugs target. It may also help scientists understand if these medicines could later be used for other cravings, such as those linked to substance use.
Small‑Molecule GLP‑1 Pills vs. Injectable Peptides
The University of Virginia team studied tiny‑molecule GLP‑1 receptor activators. These are smaller than peptide drugs like semaglutide, which appear in well‑known products such as Ozempic, Wegovy, and Rybelsus.
They focused on two oral compounds: the FDA‑approved drug orforglipron and the experimental molecule danuglipron. Because they come in pill form, they could be cheaper to produce than injectable versions.
"As more people get access to these medicines, we need to know how they work in the brain," said Dr. Lorenzo Leggio, Clinical Director of NIH’s National Institute on Drug Abuse.
How Classic GLP‑1 Drugs Cut Hunger
Scientists already know that larger peptide GLP‑1 drugs lower hunger by acting on brain regions called the hypothalamus and hindbrain.
What the small‑molecule oral drugs do after they reach the brain was less clear.
Finding a New Signal Deep in the Brain
The researchers gave mice either orforglipron or danuglipron and then mapped which brain areas lit up.
As expected, the drugs affected known appetite centers. Unexpectedly, they also turned on the central amygdala, a zone that controls desire and reward.
This area sits deeper than scientists previously thought GLP‑1 drugs could reach.
Further tests showed that when the central amygdala was activated, dopamine release dropped in key parts of the brain’s reward system while the mice were eating for fun.
Turning Down the Pleasure of Food
The results suggest oral GLP‑1 pills do more than curb physical hunger. They also weaken the brain’s “feel‑good” signals that make some foods seem extra tempting.
Future studies will test whether these next‑generation medicines can lower cravings for other substances, such as drugs of abuse.
Study Funding
The work was supported by multiple NIH grants, including awards from the National Institute of Neurological Disorders and Stroke, the National Institute of General Medical Sciences, the National Heart, Blood, and Lung Institute, and the National Cancer Institute.
This research was not a clinical trial and has not been reviewed by the FDA for any specific treatment approval.