Dopaminergic terminals in the rat cortex.

The destruction of ascending noradreniergic pathways by bilateral microinjections of 6-hydroxydopamnine made laterally to the pedunculus cerebellaris superior completely abolished the in vitro synthesis of [(3)H]norepinephrine from L-[(3)H]tyrosine in slices and in synaptosomes of the rat cortex. However, normal [(3)H]dopamine synthesis could still be observed in both cortical preparations from animals with lesions. These results provide the first biochemical support for the existence of dopaminergic terminals independent of noradrenergic terminals in the rat cortex.