Effects of drugs on the formation of 3-methoxytyramine, a dopamine metabolite, in the substantia nigra, striatum, nucleus accumbens and tuberculum olfactorium of the rat.

Abstract

Abstract 3-Methoxytyramine (3-MT) was assayed with a sensitive and rapid liquid chromatographic separation on a Sephadex G 10 column in combination with a fluorimetric detection in a continuous flow system. The method made it possible to measure pargyline-induced 3-MT concentrations in various regions of a single rat brain. After haloperidol, morphine or sulpiride treatment, pargyline-induced 3-MT concentrations in the striatum, nucleus accumbens, tuberculum olfactorium and substantia nigra of the rat were comparable with reported changes of homovanillic acid concentrations. Dose-response curves for 3-MT increase in various brain regions after (+)-amphetamine pretreatment were studied. The effect of (+)-amphetamine on 3-MT formation was much more pronounced in nerve terminal areas, especially in the mesolimbic structures. The influence of apomorphine, γ-hydroxybutyric acid, haloperidol, reserpine or combined treatment of haloperidol and (+)-amphetamine revealed pronounced differences on regional 3-MT concentrations, indicating important differences between the regulation of dopamine metabolism in the substantia nigra and nerve terminal areas.