Development of an Alcohol Deprivation and Escalation Effect in C57BL/6J Mice

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Abstract
Background: Relapse-like drinking has been studied through the expression of the alcohol deprivation effect (ADE), which is measured by a pronounced increase in ethanol preference and consumption after imposed abstinence. No studies have characterized the ADE in C57BL/6J (B6) mice. The present study examined the effects of length and number of deprivations on the expression of the ADE in B6 mice. Methods: Adult male B6 mice received 24-hour continuous access to ethanol and water for 6 weeks (baseline). Experiment 1 determined the ADE in mice receiving weekly access to 15% ethanol (i.e., exposed 1 day a week and deprived during the other 6 days) for a total of 10 weeks. Experiments 2 and 3 determined the ADE after a single 2-week deprivation period in mice receiving a single concentration of 15% ethanol or multiple concentrations of 7.5, 15, and 30% ethanol, respectively, followed by weekly access to their respective ethanol solutions for 10 weeks. Experiment 4 determined the ADE after a single 2-week deprivation period, followed by daily access to 15% ethanol. Mice never deprived of ethanol (i.e., continuous access) were used as age-matched drinking controls. Results: The ADE was observed after the initial 6-day deprivation period and was profoundly enhanced (i.e., escalation of the ADE) following weekly reexposure to 15% ethanol. Compared with a single concentration of 15% ethanol, concurrent access to multiple ethanol concentrations resulted in a near 2-fold increase in baseline ethanol consumption. Regardless of having access to single or multiple concentrations of ethanol, the ADE was not observed immediately after a 2-week deprivation period. The ADE was observed (although to a lesser magnitude and duration) following weekly reexposure to single or multiple concentrations of ethanol. Alternatively, following a 2-week deprivation period, mice receiving daily access to 15% ethanol showed a significant decrease in ethanol intake and preference (i.e., negative ADE). Conclusions: Short-term deprivations followed by repeated intermittent (weekly) reexposure to ethanol produces a robust ADE in B6 mice. Increasing the initial deprivation length to 2 weeks produces various opposing effects, including erasure of an initial ADE, diminished expression and magnitude of the ADE following weekly exposure, and complete reversal of the ADE following daily exposure to ethanol.