Increased alcohol-biased choice behavior in mouse models of high alcohol drinking

Background

Rodent models have explored the transition from controlled goal-directed consumption to habitual/compulsive intake using different procedures. This study evaluates the effect of concurrent presentation of sucrose on alcohol intake using two models that induce high levels of alcohol intake in mice that experienced chronic intermittent ethanol (CIE) exposure and/or stress.

Methods

In Experiment 1, male mice were exposed to four cycles of CIE or control (air) exposure, and once an increase in voluntary alcohol was observed in CIE mice, mice were offered a choice between alcohol or increasing concentrations of sucrose (from 0.75% to 12%; w/v). In Experiment 2, male mice experienced three cycles of CIE exposure, CIE and forced swim stress, control (air) exposure, or forced swim stress. Once elevated voluntary alcohol intake was observed in mice that experienced both CIE and stress, mice were presented with a choice between alcohol and sucrose (from 1.5% to 6%, w/v increased over consecutive days).

Results

Mice that experienced CIE exposure (Experiment 1) or CIE exposure and stress (Experiment 2) showed increased alcohol intake. In Experiment 1, the presentation of sucrose at 3% and 12% reduced alcohol intake in control mice. Only the two highest concentrations of sucrose (6% and 12%) affected alcohol intake in CIE-exposed mice. In Experiment 2, concurrent presentation of a 6% sucrose solution decreased alcohol intake in mice that experienced CIE, stress, or control exposure; however, the presentation of sucrose did not influence alcohol intake in mice that experienced both CIE and stress. The amount of sucrose consumed did not differ between groups in both experiments.

Conclusions

These experiments showed that mice that had experienced repeated CIE exposure alone or in combination with stress were more prone to continue their high levels of alcohol intake despite the presence of a sucrose solution as an alternative.