STUDIES OF AMINES IN THE STRIATUM IN MONKEYS WITH NIGRAL LESIONS

The effects of ventromedial tegmental lesions on the biosynthesis and disposition of biogenic amines in the striatum of monkeys were investigated. The concentrations of endogenous dopamine and of the intraventricularly injected ³H]dopamine were distinctly lower in the striatum on the lesion side than on the intact side. The storage of ³H]dopamine in the caudate nucleus was impaired to a much greater extent than the storage of the newly synthesized ³H]norepinephrine. The concentrations of endogenous serotonin and of the intraventricularly injected ¹⁴C]serotonin were lower in the striatum on the lesion side than on the intact side. However following MAO inhibition, the concentration of ¹⁴C]serotonin did not differ significantly on the two sides of the caudate nucleus. The in vivo biosynthesis of dopamine from tyrosine was significantly reduced in the striatum on the lesion side. Tyrosine hydroxylase and DOPA decarboxylase activities were decreased on the lesion side of the striatum as compared with the intact side. Thus, the ventromedial tegmental lesions affect the storage and the synthesis of dopamine and serotonin in the ipsilateral striatum.