Binge drinking during adolescence and adulthood may have differential long-term effects on the brain. We investigated the long-term effects of chronic intermittent ethanol (CIE) exposure during adolescence and adulthood on impulsivity and anxiety-like behavior. Adolescent (adolescent-exposed) and adult (adult-exposed) rats were exposed to CIE/water on postnatal days (PND) 28-53 and PND146-171, respectively, and a 4-day ethanol/water binge on PND181-184 and PND271-274, respectively. During withdrawal from CIE and 4-day binge exposures, anxiety-like behavior and arousal were measured in the light-potentiated startle (LPS) and acoustic startle (ASR) procedures, respectively. Impulsive choice was evaluated in the delay discounting task (DDT) at baseline and after ethanol challenges. Independent of age, ASR and LPS were decreased during withdrawal from CIE exposure. In contrast, LPS was increased in adult-exposed, but not adolescent-exposed, rats during withdrawal from the 4-day ethanol binge. CIE exposure had no effect on preference for the large delayed reward at baseline, independent of age. During DDT acquisition, CIE-exposed, compared with water-exposed rats, omitted more responses, independent of age, suggesting the CIE-induced disruption of cognitive processes. Ethanol challenges decreased preference for the large reward in younger adolescent-exposed rats but had no effect in older adult-exposed rats, independent of previous CIE/water exposure. Taken together, the present studies demonstrate that CIE withdrawal-induced decreases in anxiety and arousal were not age-specific. CIE exposure had no long-term effects on baseline impulsive choice. Subsequent ethanol exposure produced age-dependent effects on impulsivity (increased impulsivity in younger adolescent-exposed rats) and anxiety-like behavior (increased anxiety-like behavior in older adult-exposed rats).
Keywords: Acoustic startle reflex; Acute ethanol challenge; Delay discounting; Ethanol withdrawal; Impulsivity; Light-potentiated startle.
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