Assessment of anxiolytic and motor stimulant effects of ethanol in Adolescent and adult wistar rats

ACEVEDO MB; NIZHNIKOV ME; SPEAR, N.E.; PAUTASSI RM

San Francisco

Congreso; 35th Annual Scientific Meeting of the Research Society on Alcoholism; 2012

Research Society on Alcoholism

Background: It is important to assess age-related differences that may put adolescents at risk for developing alcohol-related problems. Ethanol-induced motivational effects (appetitive, aversive and anti-anxiety consequences) are important modulators of ethanol-seeking and intake. In the present study we assessed anxiolytic and motor behavioral stimulant effects of ethanol in adolescent and adult outbred Wistar rats. Methods: On postnatal day 28 or 74 (adolescents and adults, respectively), male and female animals were given ethanol (0.0, 0.5, 2.5 or 3.25 g/kg) and then assessed in an open field (size: 30 x 30 x 30 cms, and 50 x 50 x 50 cms; for adolescents and adults, respectively) for 7 minutes (post-administration time: 5–12 min). Total duration of forward locomotion and time spent in the center of the open field were measured. The former was considered as a measure of drug-induced activation, whereas the latter is thought to reflect an anxiety-like response. Time spent rearing and wall-climbing were also assessed. Results: ANOVAs indicated that overall forward locomotion was significantly higher in adult than in adolescent rats and in female than male rats. Ethanol induced significant motor activation, particularly at 3.25 g/kg, and this stimulant effect was fairly similar in adolescent and adult rats. Time spent in the center of the open field was similar in adolescents and adults treated with vehicle (0.0 g/kg). Adults given 2.5 and 3.25 g/kg ethanol, however, exhibited significantly less time in the center of the arena when compared with vehicle-treated counterparts. High (i.e., 3.25 and 2.5 g/kg) but not low (0.5 g/kg) ethanol-dose induced a significant decrease in both rearing and wall-climbing. Preliminary conclusions: Under the present experimental conditions there were no age-related differences in the motor stimulating effects of ethanol. Ethanol, however, seemed to induce anxiety-like behavior in adult but not in adolescent rats. The latter result is consistent with previous findings of adults, but not adolescents, exhibiting ethanol-induced social anxiety (Varlinskaya & Spear, 2002).