Plasma concentrations of the inflammatory adipokine lipocalin-2 are not affected by chronic alcohol exposure in rats or acute alcohol administration in people with alcohol use disorder

<i>Background:</i> The immune system and inflammation have emerged as critical components in alcohol use disorder (AUD). The inflammatory molecule lipocalin-2 (LCN2) has been investigated in alcohol-associated liver disease, and assessment of LCN2 concentrations may aid in prevention and treatment of AUD. However, it is unknown how LCN2 concentrations fluctuate in response to acute and chronic alcohol exposure.<i>Objectives:</i> We examined plasma LCN2 concentrations in rats made alcohol-dependent via chronic, intermittent alcohol vapor exposure, and in people with AUD after acute alcohol administration. We hypothesized that chronic and/or acute alcohol exposure would alter LCN2 concentrations.<i>Methods:</i> Plasma LCN2 concentrations were measured in alcohol-dependent (<i>n</i> = 9) and nondependent (<i>n</i> = 8) male rats. LCN2 concentrations were also examined in two human laboratory studies with cue-reactivity and oral/intravenous alcohol administration in 15 (80% males) and 16 (68.8% males) participants with AUD, respectively.<i>Results:</i> A significant effect of Timepoint (morning versus afternoon; <i>p</i> = .001) but not of chronic alcohol exposure on LCN2 concentrations were found in rats. No significant effects were found after acute alcohol administration in humans.<i>Conclusions:</i> Chronic alcohol exposure in rats or acute alcohol administration in people with AUD had no impact on LCN2 concentrations. In rats, LCN2 concentrations were lower in the morning than in the afternoon, indicating time-related variations in LCN2 concentrations. Together, these findings suggest that LCN2 might play a role in the circadian rhythm, which is often disrupted in people with AUD. However, prospective studies are needed to further examine LCN2's potential clinical relevance in AUD.Clinical Trials Numbers: NCT01751386, NCT01779024.