Pharmacotherapy response across ethanol craving, seeking, and consumption depends on sex and baseline phenotype in alcohol-preferring rats

Background

Alcohol use disorder (AUD) is a heterogeneous condition in which pharmacotherapies show modest efficacy and marked inter-individual variability. One explanation is that treatments differentially affect distinct behavioral components—craving, seeking, and consumption—while baseline neurobehavioral traits further shape treatment response. However, these dimensions are rarely dissociated in preclinical models. We therefore examined whether clinically relevant pharmacotherapies produce behavior- and sex-specific effects across these components, and whether baseline behavioral and neurobiological measures moderate treatment sensitivity.

Methods

Male and female alcohol-preferring rats (N=32; 16/sex) were tested in a within-subject crossover design, sequentially receiving naltrexone, bupropion, citalopram, and ondansetron across four-day treatment periods separated by a one-week washout phase. Craving was measured as premature seeking responses during the 60-s seeking-lever inactive period in a seeking–taking task, in which a seeking lever press grants access to a taking lever resulting in 15% ethanol delivery. Seeking was measured as completed seeking–taking trials, and consumption as Pavlovian ethanol intake during non-contingent access. Baseline measures included anxiety-like behavior (elevated plus maze), negative urgency and impulsivity (modified seeking–taking task), motivation (progressive ratio), baseline drinking (Pavlovian intake), resting-state functional connectivity (fMRI), dopamine and serotonin transporter availability (positron emission tomography), and plasma neurofilament light chain (ELISA). Data were analyzed using repeated-measures and mixed-effects moderation models.

Results

Pharmacotherapies produced behavior- and sex-specific effects across ethanol craving, seeking, and consumption. Craving was robustly reduced by naltrexone, citalopram, and ondansetron (all p<0.001), whereas bupropion increased craving in males (p=0.013). Seeking was reduced by naltrexone and citalopram across sexes (both p<0.001), and by ondansetron primarily in females (p=0.0098), while bupropion reduced seeking in females (p=0.0226) but increased it in males (p=0.006). Consumption was reduced by naltrexone (p=0.016), ondansetron (p=0.007), and citalopram (p<0.001), with naltrexone and ondansetron effects driven by males and citalopram reducing consumption in both sexes. Baseline phenotype significantly moderated pharmacotherapy response. Higher motivation and negative urgency were associated with altered pharmacotherapy sensitivity, particularly under bupropion (craving; β≈−17, p=0.002) and naltrexone (seeking; β≈+28, p=0.029). Anxiety showed sex-dependent effects: lower anxiety was associated with reduced seeking under naltrexone in females (β≈−27, p=0.049), whereas higher anxiety predicted stronger reductions in consumption under naltrexone (β≈−11, p=0.028) and ondansetron (β≈−12, p=0.011). Higher baseline drinking predicted weaker pharmacotherapy-induced reductions in consumption in males across bupropion (β≈+27, p=0.003), naltrexone (β≈+23, p=0.011), and ondansetron (β≈+20, p=0.022), indicating reduced treatment sensitivity in heavier drinkers. Cingulate–prelimbic and insular networks functional connectivity significantly moderated bupropion, where stronger connectivity was associated with greater reductions in craving and seeking (p<0.001). Higher plasma neurofilament light chain in females only were associated with a reduced responding under citalopram (β≈−0.98, p=0.049), and naltrexone (β = −0.93, p = 0.060), whereas dopamine and serotonin transporter availability showed limited effects.

Conclusions

Pharmacotherapy effects in alcohol-preferring rats differ across ethanol craving, seeking, and consumption, and are strongly influenced by sex and baseline neurobehavioral state. Dissociating these behavioral components and incorporating individual variability may improve mechanistic interpretation and translational alignment of pharmacotherapy development in AUD.

References

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