Consistent with developmental shifts in GABAA receptor expression within specific brain regions, the cerebellum displays levels of α6 subunit expression that increase with age and expression of α1, γ2, β2, β3, and δ subunits that decreases with age (Gutiérrez et al. 1997). Within the hippocampus, consistently high levels of γ2 and α5 subunit expression are found across development, the α1 subunit shows decreasing levels through development and aging (Yu et al. 2006), and levels of the δ subunit mRNA increase throughout development, with the highest levels being found in adults (Laurie et al. 1992). Increasing levels of the δ subunit mRNA across development are interesting, given the proposed link of δ-GABAA receptors to low-dose ethanol sensitivity (Choi et al. 2008). Considering that adolescents are less sensitive to ethanol’s motor ataxic effects compared to adults, and δ subunit mRNA levels are lower in adolescents compared to adults, it is tantalizing to speculate that this subunit is a critical mediator underlying the changes in ethanol’s effect on GABAA receptors across development. Overall, because GABAA receptor subunit expression differs across development, it is
