Ontogeny of the stimulant and sedative effects of ethanol in male and female Swiss mice: gradual changes from weaning to adulthood

Abstract

From weaning to early adulthood, the acute stimulant and sedative effects of ethanol show gradual changes that are similar in male and female mice. Although the initial tolerance to the sedative effects of ethanol contributes to the changes in ethanol-induced locomotor activity, young mice also show a higher sensitivity to the stimulant effects of ethanol.

Developmental differences in ethanol-induced sensitization using postweanling, adolescent, and adult Swiss mice

“…1, ethanol-induced locomotor stimulation was significantly higher in postweanling than in adult mice for all doses between 1.5 and 2.5 g/kg. Similar results have been found in other laboratories, in different strains of both male and female mice (Hefner and Holmes 2007;Quoilin et al 2010;Stevenson et al 2008). Therefore, this higher sensitivity of younger mice to the stimulant effects of ethanol seems to be a robust effect.…”

“…Indeed adolescence in mice, which covers the period ranging from weaning to the entrance in adulthood, may be subdivided into shorter periods, each being associated with specific behavioral and neurobiological changes (Tirelli et al 2003). As shown in previous experiments carried out in our laboratory (Quoilin et al 2010), behavioral responses to ethanol gradually change during adolescence, with the youngest 21-day-old mice and adults exhibiting the greatest differences. We have therefore decided to study these two groups of 21-and 63-day-old mice, together with an intermediate age (35-dayold mice).…”

“…As human adolescents typically adopt binge drinking behaviors, it is important to extend those studies on ethanol-induced sensitization to higher ethanol doses. This is especially important because our previous studies have shown that higher doses of ethanol, up to 3.5 g/kg, maintain their stimulant effects in adolescent mice in contrast to adult mice in which these doses are mainly depressant (Quoilin et al 2010).…”

“…Empirical evidence in support of this explanation has been mainly provided by animal research. Regarding the adverse and unpleasant effects of alcohol, a lower sensitivity to the sedative (Little et al 1996;Quoilin et al 2010;Silveri and Spear 1998), ataxic (White et al 2002), and hypothermic (Silveri and Spear 2000) effects of ethanol have been reported in adolescent relative to adult rats and mice. In contrast, adolescent rodents have been shown to be more sensitive than adults to the locomotor stimulant effects of ethanol (Quoilin et al 2010;Stevenson et al 2008) and to ethanol-induced social facilitation (Varlinskaya and Spear 2002).…”

“…In the first experiment, we tested whether the 2.5-g/kg ethanol dose, typically used in most adult sensitization studies, induces different profiles for the development and expression of sensitization in our three age groups of female Swiss mice. As young mice show much more potent ethanol-induced locomotor stimulation than adult mice (Quoilin et al 2010), the lack of sensitization in young mice might be attributed to a ceiling effect. In order to test this hypothesis, experiment 2 tested the development and expression of sensitization with a lower ethanol dose.…”