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A direct comparison has been made of the drug-induced changes in extracellular levels of 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid measured using intracerebral dialysis and differential pulse voltammetry with carbon fibre electrodes. The comparison was carried out in chloral hydrate anaesthetized rats with a pretreated carbon fibre electrode implanted in one striatum and an intracerebral dialysis loop in the contralateral striatum. 3,4-Dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid in the dialysis perfusates were assayed by high pressure liquid chromatography with electrochemical detection. d-Amphetamine (2 mg/kg) decreased extracellular 3,4-dihydroxyphenylacetic acid and the height of the 3,4-dihydroxyphenylacetic acid oxidation peak, while haloperidol (0.5 mg/kg) increased 3,4-dihydroxyphenylacetic acid levels measured in the perfusates and the height of the 3,4-dihydroxyphenylacetic acid oxidation peak. In these experiments there were parallel changes in 3,4-dihydroxyphenylacetic acid levels and peak height and a close correlation between these changes. Tranylcypromine (10 mg/kg) produced an almost parallel decrease in extracellular 5-hydroxyindoleacetic acid (dialysis) and the height of the 5-hydroxyindoleacetic acid oxidation peak, with similar percentage changes and good correlation values being obtained. However, while 5-hydroxy-L-tryptophan (25 mg/kg) increased both the 5-hydroxyindoleacetic acid levels and the height of the 5-hydroxyindoleacetic acid oxidation peak, 5-hydroxyindoleacetic acid in the dialysis perfusates showed a greater increase than the oxidation peak. The results show a close correlation between changes in extracellular 3,4-dihydroxyphenylacetic acid and its respective voltammetric peak and strongly support the use of in vivo differential pulse voltammetry for monitoring dopamine metabolism.(ABSTRACT TRUNCATED AT 250 WORDS)


Journal article



Publication Date





1213 - 1221


3,4-Dihydroxyphenylacetic Acid, 5-Hydroxytryptophan, Animals, Chromatography, High Pressure Liquid, Corpus Striatum, Dialysis, Electrochemistry, Hydroxyindoleacetic Acid, Male, Phenylacetates, Rats, Rats, Inbred Strains, Tranylcypromine