Decreased striatal Drd1 mRNA expression during the early, but not late, phase of motor skill learning.

<p>(A) Regional analysis of dopamine D1 receptor (Drd1) mRNA expression within sub-regions of the striatum of (top panel) early phase (EP) active controls (white bars) vs. EP trained rats (red bars), and of (bottom panel) late phase (LP) active controls (white bars) vs. LP trained rats (blue bars). Data in bar graphs show mean optical density (OD) values for Drd1 mRNA in the DMS, DLS, VLS, AcbC, and AcbSh. The results are presented as means ± SEM; <i>n</i> = 5 per group. Asterisks indicate where trained rats differ significantly (*<i>P</i> < 0.05 and **<i>P</i> < 0.01) from active control rats. (B) Representative autoradiographs showing the mRNA expression levels of Drd1 at the level of the striatum of active controls and trained rats during the early and late phases of motor skill learning. For more details, see Figs <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140974#pone.0140974.g001" target="_blank">1</a> and <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140974#pone.0140974.g002" target="_blank">2</a>.