Changes in monoamine metabolites measured by simultaneous in vivo differential pulse voltammetry and intracerebral dialysis.
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)
D015102:3,4-Dihydroxyphenylacetic Acid / Q000032:analysis*; D006916:5-Hydroxytryptophan / Q000494:pharmacology; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003342:Corpus Striatum / Q000032:analysis*; D003956:Dialysis; D004563:Electrochemistry / Q000379:methods; D006897:Hydroxyindoleacetic Acid / Q000032:analysis*; D008297:Male; D010648:Phenylacetates / Q000032:analysis*; D051381:Rats; D011919:Rats, Inbred Strains; D014191:Tranylcypromine / Q000494:pharmacology
D010648:Phenylacetates; D015102:3,4-Dihydroxyphenylacetic Acid; D014191:Tranylcypromine; D006897:Hydroxyindoleacetic Acid; D006916:5-Hydroxytryptophan