Morphometric analysis of prefrontal cortical development following neonatal lesioning of the dopaminergic mesocortical projection.

In this study the possibility that dopamine (DA) plays a trophic role in cortical development was studied by analysing cortical morphology and dendritic arborization of pyramidal cells after neonatal depletion of DA. The prefrontal cortex (PFC) was depleted of a DA innervation from postnatal day 1 onwards by thermal lesions of the DA cell group (A10) in the ventral tegmental area. Measurements of the cortical thickness and volume of the PFC subareas did not reveal any gross alterations. The DA-depleted animals, however, showed a 30% decrease in the total length of the basal dendrites of the pyramidal cells in layer V of the medial PFC. These cells constitute the primary target of the dopaminergic innervation in the prefrontal cortex. The decreased dendritic length was due mainly to a reduced branching frequency of the basal dendrites. The present results of the dendritic measurements support a trophic role for DA in neuronal differentiation.