Ethanol-Mediated Motor Stimulation and Ethanol-Mediated Appetitive Reinforcement In Adolescent Rats.

ACEVEDO MB; MOLINA JC; PAUTASSI RM

PARIS

Congreso; 2010 International Society for Biomedical Research on Alcoholism (ISBRA) World Congress. Paris, France, September, 13-16, 2010.; 2010

ISBRA

Animal models have pinpointed several factors associated with the avidity for alcoholduring the adolescence stage. Adolescents are less sensitive than adults to severaleffects of ethanol that serve as deterrents, preventing the escalation in intake (e.g.,sedation, Spear et al., 2000). Adolescent rats are also highly sensitive to the locomotoractivating effects of this drug (Acevedo et al., 2008). Spontaneous and ethanolinducedactivation have been hypothesized to predict ethanol reinforcement and selfadministration.This study assessed the expression of conditioned tactile preference(CTP) by ethanol in adolescent rats. Unlike mice, adult rats rarely express conditionedpreference towards tactile or environmental cues paired with ethanol. Another aimwas to characterize the relationship between spontaneous or ethanol-induced motoractivity in a novel environment and CTP by ethanol. The underlying hypotheses werethat adolescents would show CTP by ethanol and those rats more sensitive to thedrug’s motor stimulating effects would show greater CTP. At postnatal day 28 (PD28),adolescents were given ethanol (2.5 g/kg; i.g.) or vehicle and screened for motoractivation (7 min) in an inescapable novel environment. This relatively high dose ofethanol (2.5 g/kg) induced reliable behavioral activation. CTP training took place duringPDs 30-33: animals were given daily pairings of 1.0 g/kg ethanol and a rough surface(sandpaper, conditioned stimulus, CS). At test (PD34), adolescents given sandpaperethanolpairings displayed greater preference for the CS than controls (animals givensandpaper-vehicle pairings). This appetitive conditioning was unrelated with the levelof motor activation induced by ethanol on PD28. Yet, there was a significant positivecorrelation between spontaneous motor activity in the novel environment and theexpression of ethanol-induced tactile preference. These results indicate that, unliketheir adults counterparts, adolescent rats readily express conditioned preference for atactile cue paired with low-dose alcohol. Our expectation of this learning being relatedto the amount of activity induced by the drug was not fulfilled. The positive associationbetween CTP by ethanol and spontaneous activity, however, fits well with the possibilitythat activity in novel and inescapable environments relates to the novelty-seeking traitin humans, which in turn is a predictor of abuse liability of drugs.