Reduction of dopamine utilization in the prefrontal cortex but not in the nucleus accumbens after selective destruction of noradrenergic fibers innervating the ventral tegmental area in the rat.

The present study was made to determine the role of the noradrenergic (NA) neurons which innervate the ventral tegmental area (VTA) in the regulation of VTA dopaminergic (DA) neurons projecting to the prefrontal cortex and the nucleus accumbens. For this purpose, a 6-hydroxydopamine lesion was made in benztropine pretreated rats medially just above the decussatio of the pedunculus cerebellaris superior in order to specifically destroy the NA fibers innervating the VTA without affecting those projecting to the prefrontal cortex. Seven days later the ratio of DOPAC and DA levels was estimated in the prefrontal cortex and the nucleus accumbens and used as an index of DA utilization. In the lesioned rats the DOPAC/DA ratio was significantly decreased in the prefrontal cortex but not in the nucleus accumbens. These results suggest that the NA neurons which innervate the VTA exert a specific tonic excitatory influence on the mesocortico-prefrontal DA neurons.