Behavioral characterization of withdrawal following chronic voluntary ethanol consumption via intermittent two-bottle choice points to different susceptibility categories.

BACKGROUND

Alcohol is among the most commonly abused drugs worldwide. Cessation of chronic alcohol consumption can result in the appearance of withdrawal symptoms that commonly promote relapse in individuals with alcohol use disorder (AUD). Thus, preclinical models of voluntary alcohol consumption, in which animals manifest spontaneous signs of withdrawal after alcohol cessation, can be useful for studying AUD and its treatment. The intermittent two-bottle choice paradigm (I2BC) has been used extensively to examine alcohol intake in rodents. However, previous studies have reported conflicting observations regarding its potential to result in the spontaneous manifestation of withdrawal upon alcohol cessation.

METHODS

We employed a battery of behavioral tests to examine the emergence of affective and physical signs of withdrawal in female and male mice exposed to alcohol in the I2BC for 10 weeks. Specifically, mice of both sexes undergoing 24-h withdrawal from the I2BC were tested for physical signs of withdrawal, anxiety-like behavior in the open field arena (OFA) and elevated plus maze (EPM), and anxiety/compulsive-like behavior in the marble burying test (MBT). The main outcomes from these tests were combined into a behavioral severity score to describe the overall behavioral phenotype.

RESULTS

Both female and male mice undergoing withdrawal from the I2BC displayed elevated physical signs of withdrawal and anxiety-associated behavior in the EPM and MBT. Analysis of the overall behavioral severity score revealed more severe phenotypes in female and male mice undergoing withdrawal from the I2BC than controls. Additionally, stratification of the mice based on severity scores demonstrated a differential distribution of severities between the exposure groups.

CONCLUSIONS

We confirmed that a significant fraction of mice chronically exposed to alcohol in the I2BC display spontaneous withdrawal. In addition, we showed that computing a severity score from a combination of behavioral metrics can be useful in preclinical research to model evaluation tools used in patients with AUD.