A novel peptide that simultaneously activates GLP-1 and neuropeptide Y receptors reduced both fentanyl self-administration and relapse-like drug-seeking in male and female rats by dampening dopamine release in the brain's reward center.
Reduced fentanyl-evoked dopamine in the nucleus accumbensGEP12 crossed the blood-brain barrier and directly dampened the reward signal that drives opioid addiction in both male and female rats
What the researchers found
GEP12, administered at doses of 1.57 or 12.53 μg/kg intraperitoneally, reduced voluntary fentanyl self-administration (2.5 μg/kg IV) in both male and female rats and shifted the fentanyl dose-response curve downward. The drug also reduced fentanyl-seeking behavior during reinstatement after extinction — a model of relapse.
Using fiber photometry, the researchers demonstrated that GEP12 reduced fentanyl-evoked dopamine release in the nucleus accumbens, identifying a central mechanism for its anti-addiction effects. Importantly, the behaviorally effective doses did not alter food intake or produce malaise-like side effects, suggesting a therapeutic window exists.
Why it matters
The opioid crisis has limited effective pharmacotherapies. Current medications like methadone and buprenorphine target opioid receptors directly, but this study explores a completely different approach — using peptide-based drugs that act on appetite and reward circuits. The fact that a GLP-1-based triple agonist can reduce opioid-seeking without causing nausea or food suppression opens a potential new treatment avenue for opioid use disorder.
How the study worked
Rats were allowed to self-administer intravenous fentanyl (2.5 μg/kg per infusion) for 21 days to establish addiction-like behavior. They were then pretreated with either vehicle or GEP12 (1.57 or 12.53 μg/kg, injected into the abdomen) before test sessions measuring drug-taking and drug-seeking. In vivo fiber photometry was used to measure real-time dopamine release in the nucleus accumbens during fentanyl self-administration.
What this study cannot tell us
This is an animal study using rats, and the results may not translate directly to humans. The study did not test long-term safety or efficacy, and the specific doses used in rats would need to be recalculated for human trials. The reinstatement model is an approximation of human relapse, not a perfect analog.
How to read the evidence
This is a preclinical animal study in rats. While the experimental design is rigorous (dose-response curves, fiber photometry, both sexes), it has not been tested in humans and represents early-stage evidence.
When this study was published
Published in 2025, this is cutting-edge research reflecting the newest direction in peptide-based addiction pharmacotherapy.
The bigger picture
This study builds on a growing body of evidence suggesting GLP-1 receptor agonists (like semaglutide) may reduce addictive behaviors beyond food. By combining GLP-1 activation with neuropeptide Y receptor targeting, the triple agonist approach may provide stronger anti-addiction effects while minimizing the nausea that limits single GLP-1 drugs. It represents a new pharmacological class for treating substance use disorders.
Questions still open
- Would GLP-1R/Y1/Y2 triple agonists show similar anti-addiction effects in humans with opioid use disorder?
- Could existing GLP-1 drugs like semaglutide provide partial benefits for opioid addiction, or is the triple receptor approach necessary?
- Does GEP12's effect on dopamine release extend to other addictive substances beyond fentanyl?
Common questions
How does a GLP-1 drug reduce opioid addiction?
Is this related to drugs like Ozempic or Wegovy?
Read the original research
A GLP-1R/Y1 receptor/Y2 receptor triple agonist decreases fentanyl-evoked dopamine release in the nucleus accumbens and attenuates fentanyl taking and seeking in rats.
British journal of pharmacology, 182(18), 4363-4379
Citation
Caffrey, Antonia; Lavecchia, Enzo; Chichura, Kylie S; Hayes, Matthew R; Doyle, Robert P; Schmidt, Heath D. (2025). A GLP-1R/Y1 receptor/Y2 receptor triple agonist decreases fentanyl-evoked dopamine release in the nucleus accumbens and attenuates fentanyl taking and seeking in rats.. British journal of pharmacology, 182(18), 4363-4379. https://doi.org/10.1111/bph.70096