Fig. 2: Adolescent changes in acetylcholine and dopaminergic systems.

A ACh system changes across adolescence. Top: regional changes in nAChR subunit expression have been noted across adolescence, with a peak in late adolescence of α4 receptor expression in the VTA, as assessed with YFP tagging, and with a gradual lessening of α5, α6, and α7 receptors in the VTA between adolescence and adulthood. Dotted lines represent periods where expression has not yet been studied. Bottom: α4β2-containing nAChR function in the PFC and striatum increases from late adolescence to adulthood. ChAT function changes across adolescence in the PFC and in the midbrain, with a peak in function in mid- to late adolescence before declining to adult levels. B Dopamine system changes across adolescence. Top: In the PFC, DA innervation increases steadily across adolescence until reaching a plateau around PND 60. DA receptor expression in the PFC peaks in mid-adolescence before declining to adult levels. Bottom: DA content in the striatum increases across adolescence, while DA receptor expression peaks in mid-adolescence. This peak appears to be sex specific, as it has been confirmed in male rodents, but was not seen in females.