ADOLESCENT RATS ARE SENSITIVE TO ETHANOL-INDUCED LOCOMOTOR STIMULATION

MILLER, S.; ARIAS, C.; SPEAR, N.E.

San Diego

Congreso; Research society on Alcoholism; 2009

Heterogeneous adult rats rarely show ethanol-induced locomotor stimulation. Infants during the first 2-3 postnatal weeks, however, are indeed sensitive to ethanol-induced locomotor stimulation, even when given relatively high ethanol doses. Our goal was to test and analyze ethanol-induced locomotor effects in heterogeneous adolescent rats. On postnatal day 32, male and female rats were intragastrically administered 0, 0.5, 1.0, or 2.5 g/kg of ethanol. Testing began 5 minutes post-administration and continued for 5 minutes in a novel environment, which automatically measured activity. All rats were again placed into this environment at 30 minutes post-administration, for 5 minutes. Ethanol-induced locomotor stimulation was observed for all ethanol doses, at both post-administration times and in the absence of any sex differences. Like infant rats but unlike heterogeneous adults, adolescent rats exhibit ethanol-induced locomotor activation. Since infants and adolescents ingest ethanol and apparently show ethanol-induced appetitive reinforcement more readily than adult rats, these results: (1) support an association between ethanol-induced locomotor stimulation and sensitivity to ethanol-mediated reinforcement; and (2) suggest that the transition between the infant and adolescent response to ethanol is more gradual than abrupt.