Prefrontal cortex: dense dopaminergic input in the newborn rat.

Using a recently introduced modification of the aluminum-formaldehyde histofluorescence method, in combination with exogeneous administration of alpha-methylnoradrenaline and biochemical analyses, a remarkably advanced development of the dopaminergic and noradrenergic afferent to the frontal lobe has been demonstrated in neonatal rat. At birth, the density and general distributional pattern of the catecholamine innervation was similar to that found in the fully developed prefrontal cortex. The previously not recognized, early and extensive maturation of the mesocortical dopamine projection suggests a functional role of dopamine already in the early postnatal period.