A new review explores how GLP-1 receptor agonists may blunt alcohol and drug reward signals, opening a promising but still unproven path toward repurposed treatments for addiction.
Review: The role of glucagon-like peptide 1 (GLP-1) in addictive disorders. Image Credit: VectorMine / Shutterstock
In a recent review published in the British Journal of Pharmacology, the authors reviewed how glucagon-like peptide 1 receptor (GLP-1) agonists may reduce alcohol and drug-seeking behaviors and evaluated their potential as treatments for addictive disorders.
Background
Every year, millions of people worldwide struggle with addiction to alcohol, nicotine, opioids, cocaine, and stimulants, yet treatment options remain limited, and relapse rates stay alarmingly high. Scientists are increasingly exploring whether medications already used for Type 2 diabetes mellitus and obesity could help reduce cravings and substance dependence. GLP-1 helps regulate appetite and blood glucose levels; however, it also affects the brain's reward pathways associated with addictive and compulsive behaviors. More research will be required on the long-term safety and effectiveness of these medications in humans before they can be officially recommended.
GLP-1 and addiction pathways
GLP-1 is a hormone released from intestinal cells after food intake. It helps regulate blood glucose levels, slows gastric emptying, and reduces appetite. Apart from the digestive system, GLP-1 is produced in the brain, especially in the nucleus tractus solitarius (NTS), where it functions as a neurotransmitter.
Consumption of drugs or alcohol can alter dopamine signaling in mesolimbic reward pathways, which helps reinforce substance-seeking behavior. Research indicates that many addictive substances acutely increase dopamine signaling, although addiction also involves broader neurochemical, stress, learning, genetic, and environmental mechanisms.
GLP-1 receptor agonists such as exenatide, liraglutide, semaglutide, and dulaglutide are already approved for treating Type 2 diabetes mellitus and obesity, which interests researchers in further research. Since these medications have established safety profiles in approved metabolic indications, researchers feel they could potentially be repurposed for addiction treatment more quickly than entirely new drugs, although safety and tolerability in people with alcohol or substance use disorders still require dedicated testing.
Effects on alcohol use disorder
Alcohol use disorder is associated with substantial mortality and global disease burden, and there are various medications that have shown limited success in treating these disorders, such as naltrexone and acamprosate. Recent research in animal models has suggested that GLP-1 receptor agonists have considerable potential for reducing alcohol consumption.
Research on rats, mice, and nonhuman primates shows that GLP-1 medications such as liraglutide, exenatide, and dulaglutide are capable of decreasing both the amount of alcohol consumed and the reward value associated with consuming alcohol. Further research suggests that GLP-1 agonists are also effective at decreasing the risk of relapse-like drinking following a period of abstinence from alcohol. However, the review noted that studies in truly alcohol-dependent animals remain limited, and many models have focused on reinforcing effects rather than continued drinking despite negative consequences.
Long-acting GLP-1 receptor agonists showed particularly promising outcomes. Dulaglutide consistently reduced drinking levels in both male and female rats without clear tolerance development. Exenatide and liraglutide have both shown reductions in drinking levels when utilized on alcohol-prone African vervet monkeys with no adverse effects of nausea or vomiting. Two alcohol-focused clinical trials are exploring whether patients with alcohol use disorder can reduce heavy drinking days and decrease alcohol craving using weekly injections of exenatide.
Influence on cocaine, nicotine, and opioid dependence
The potential benefits of GLP-1 receptor agonists extend beyond alcohol. Evidence suggests that GLP-1 receptor agonists may help reduce cocaine-related reward and drug-seeking behaviors in preclinical studies. Some studies indicate these drugs can reduce cocaine self-administration and relapse-like drug seeking. In several animal species, for example, the drug exenatide has been able to help reduce cocaine self-administration, decrease the frequency of relapse-like behavior, and reduce dopamine release after cocaine is consumed. However, early human evidence for cocaine use disorder remains limited and mixed.
Research on nicotine addiction has also produced promising findings. Animal studies demonstrated that exenatide reduced nicotine self-administration, nicotine-related reward behaviors, and dopamine release in the nucleus accumbens. An early human pilot trial reported that exenatide combined with nicotine replacement therapy improved smoking abstinence and reduced cravings. Additional clinical studies involving liraglutide and dulaglutide are ongoing.
Some rodent studies found that exenatide reduced oxycodone self-administration and heroin-seeking behaviors, while others reported minimal effects on morphine-related behaviors. Human trials are now evaluating whether liraglutide can reduce opioid cravings in patients with opioid dependence. Studies involving amphetamines also suggest that GLP-1 receptor activation may reduce stimulant-related reward behaviors and hyperactivity, although no clinical trials for stimulant use disorder were identified in the review.
Dopamine regulation and brain mechanisms
One of the most significant findings across studies is the influence of GLP-1 receptor agonists on dopamine regulation. Dopamine signaling in the mesolimbic reward pathway plays an important part in addiction by reinforcing pleasurable experiences and facilitating the repetitive use of substances.
GLP-1 receptor agonists reduced dopamine release following stimulatory effects produced by alcohol, cocaine, nicotine, and amphetamines in animal studies. Although GLP-1 receptor agonists do not completely eliminate dopamine function, these medications appeared to reduce substance-induced dopamine activity without consistently suppressing baseline dopamine signaling. This selective action may explain why they could potentially reduce drug-seeking behaviors without broadly suppressing normal motivation, although this remains to be confirmed in humans.
Researchers believe GLP-1 receptor agonists may also affect stress pathways linked to relapse. Some studies found that GLP-1 receptor stimulation reduced anxiety-like behaviors during alcohol withdrawal and decreased relapse-like drinking patterns. These findings suggest that GLP-1 therapies may target both reward-seeking and stress-driven addiction behaviors, but the review emphasized that stress-system effects are complex and not yet fully understood.
Although nausea and reduced food intake can occur with some GLP-1 receptor agonists, many studies showed reduced alcohol and drug-seeking behaviors even when substances were administered intravenously, suggesting the effects go beyond simple appetite suppression.
Conclusion
Research into GLP-1 receptor agonists has opened a promising new direction for addiction treatment. Evidence from animal studies, nonhuman primate work, and limited early human data suggests that these medications may reduce alcohol consumption, drug cravings, relapse behaviors, and dopamine-driven reward responses.
Because several GLP-1 receptor agonists are already approved for Type 2 diabetes mellitus and obesity, they may reach addiction treatment settings more rapidly than newly developed drugs if clinical efficacy is proven. However, questions remain regarding long-term effectiveness, sex differences, brain-specific mechanisms, and safety in people with severe substance dependence.
Larger clinical trial studies are needed before these medications are prescribed for individuals who have an addiction.
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