Spontaneous Early Withdrawal Behaviors after Chronic 24-hour Free-Choice Access to Ethanol

Abstract

Abstract Aims Abstinence after chronic alcohol consumption leads to withdrawal symptoms, which are exacerbated after repeated cycles of relapse. This study examined withdrawal-like behaviors after chronic ethanol drinking, with or without repeated cycles of deprivation. Methods Male alcohol-preferring (P) rats had access to continuous ethanol (CE), chronic ethanol with repeated deprivation (RD), or remained ethanol naïve (EN). The RD group experienced seven cycles of 2 weeks of deprivation and 2 weeks of re-exposure to ethanol after an initial 6 weeks of ethanol access. Withdrawal was measured after an initial 24 h of ethanol re-exposure in the RD group, which coincided with the same day of ethanol access in the CE group. Withdrawal-like behavior was measured by (a) ethanol intake during the initial 24 h of re-exposure, (b) locomotor activity (LMA) in a novel field 9–13 h after removal of ethanol at the beginning of the fifth re-exposure cycle and (c) acoustic startle responding (ASR) 8–15 h after removal of ethanol at the beginning of the sixth re-exposure cycle. Results The RD rats displayed a 1-h alcohol deprivation effect (ADE) (temporary ethanol increase), relative to CE rats, during the first to fourth and seventh re-exposure cycles. RD and CE rats displayed significant increases in LMA than EN rats. Regarding ASR, RD rats displayed significantly greater ASR relative to EN rats. Conclusion This study confirms that P rats meet the animal model criterion for ethanol-associated dependence, without a reliance on either behavioral (limited fluid access) or pharmacological (seizure threshold manipulation) challenges.