Semaglutide, Tirzepatide, and Retatrutide Attenuate the Interoceptive Effects of Alcohol in Male and Female Rats
This preclinical study examined whether three incretin-based receptor agonists — semaglutide (GLP-1 receptor agonist), tirzepatide (dual GLP-1/GIP receptor agonist), and retatrutide (triple GIP/GLP-1/glucagon receptor agonist) — could alter the interoceptive (subjective) effects of alcohol in rats using an operant drug discrimination paradigm. Male and female rats were trained to discriminate alcohol from saline, then tested after acute or repeated drug administration. The study found that acute administration of all three compounds reduced alcohol's discriminative stimulus effects, suggesting each compound modulated how the animals internally perceived alcohol. Repeated semaglutide treatment sustained this effect across a 15-day period, though discrimination returned to baseline levels within three days of stopping treatment. The authors interpret these findings as potentially relevant to understanding why GLP-1 receptor agonists reduce drinking behavior in humans, hypothesizing that blunting alcohol's subjective effects may be a contributing mechanism. Key limitations include the exclusive use of an animal model, meaning translation to human subjective experience remains uncertain, and the study does not establish clinical efficacy or safety in people with alcohol use disorder.
Why this grade: All experimental findings are derived exclusively from male and female rats using an operant drug discrimination model, with no human subjects involved, and the work is a preprint not yet peer-reviewed.
Rationale Alcohol use disorder (AUD) remains a major public health challenge, yet effective pharmacotherapies are limited. As such, there is growing interest in repurposing medications with novel mechanisms of action. Glucagon-like peptide-1 (GLP-1) receptor agonists, originally developed for type 2 diabetes, have emerged as promising candidates due to effects on intake regulation and reward processing. GLP-1 receptor agonists, including semaglutide, reduce alcohol intake and relapse-like behaviors in rodent and non-human primate models, and a recent clinical trial found that semaglutide decreased alcohol craving and drinking in adults with AUD. Modulation of the subjective/interoceptive effects of alcohol may contribute to the therapeutic potential of GLP-1 receptor agonists. Objectives This study used operant drug discrimination in male and female rats to assess how acute and repeated semaglutide treatment affects alcohol’s discriminative stimulus (interoceptive) effects. We hypothesized that GLP-1 receptor activation would disrupt alcohol’s interoceptive effects. We also evaluated acute treatment with tirzepatide, a dual GLP-1/gastric inhibitory peptide (GIP) receptor agonist, and retatrutide, a triple GIP/GLP-1/glucagon receptor agonist, to determine whether broader receptor activity would differentially influence alcohol’s subjective effects. Results Acute administration of semaglutide, tirzepatide, and retatrutide each attenuated alcohol discrimination, suggesting modulation of subjective alcohol effects. Repeated semaglutide maintained efficacy across the 15-day treatment period; alcohol discrimination returned to control levels three days after treatment cessation. Conclusions Building on prior work with GLP-1 receptor agonists, these results provide important context for interpreting clinical observations of reduced drinking behavior among individuals receiving this class of therapeutics.
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