Effects of voluntary adolescent intermittent alcohol exposure and social isolation on adult alcohol intake in male rats

Adolescent Intermittent Ethanol Drives Modest Neuroinflammation but Does Not Escalate Drinking in Male Rats

“…Rats in the standard condition had access to NIH-guided environmental enrichment (EE, PVC pipe) in the home cage, while those in the impoverished and isolation conditions did not. Polycarbonate cages were used for all rats in the study, but rats in the isolation condition had metal grid flooring with no bedding material, and cages were visually blocked off from one another using poster board, to mimic social isolation and housing conditions as in our previous experiments [42,53,54]. All animal experimentation was approved in advance by The University of Texas at Austin Institutional Animal Care and Use Committee and was consistent with the Guide for the Care and Use of Laboratory Animals [49].…”

“…First, rats were acclimated to being singly housed with two bottles containing distilled water in the home cage (PND 87-100). On PND 101, one of the water bottles was switched out for ethanol in distilled water, while the other bottle always contained water (as previously described) [42]. Access to alcohol was not limited, and the two bottles were left in the cages 24 h a day.…”

“…One day after cessation of 2BC (PND 111), rats in the standard group were transcardially perfused (2BC group; AIE n = 8, AIS n = 8) and brains harvested. For the impoverished and isolation groups, rats were offered an identical 3% to 9% range of ethanol concentrations beginning on PND 101, but then extended up to 20%, as used previously [42]. The two bottles in each cage were counterbalanced for left or right side daily, and bottles were weighed every day to measure intake.…”

“…Exposure to alcohol during adolescence also escalates adult drinking in some animal models [36][37][38][39][40][41] but not others, e.g., [42][43][44][45][46]. For example, in rats, escalation in drinking following adolescent exposure has been modeled with adolescent intermittent ethanol exposure (AIE) followed by testing two-bottle free-choice (2BC) alcohol drinking in adulthood [36,37,39,47].…”

“…For example, in rats, escalation in drinking following adolescent exposure has been modeled with adolescent intermittent ethanol exposure (AIE) followed by testing two-bottle free-choice (2BC) alcohol drinking in adulthood [36,37,39,47]. However, both forced exposure, such as binge models via intragastric gavage or as sole source of liquids, and some voluntary consumption models, such as 2BC, have failed to produce an escalation in adult alcohol drinking [42][43][44][45][46]. One commonality among the models that successfully escalated adult drinking is single housing of the animals.…”