Voltammetric carbon paste electrodes monitor uric acid and not 5-HIAA at the 5-hydroxyindole potential in the rat brain.
Changes in the height of peak 2 obtained using linear sweep voltammetry and carbon paste electrodes chronically implanted in discrete brain regions of the unrestrained rat were measured under a variety of conditions; in the past this peak has been attributed to the oxidation of 5-hydroxyindoleacetic acid (5-HIAA). Unilateral 5,7-dihydroxytryptamine (5,7-DHT) lesions of the medial forebrain bundle reduced the 5-HIAA content of the striatum and hippocampus to 10% of the unlesioned side, but did not alter the height of peak 2 recorded in these regions. In contrast, microinfusion of uricase beside striatial electrodes reduced the height of peak 2 by 96%; systemic amphetamine-induced increases in the height of the peak were also prevented by this enzyme. These results indicate that uric acid, and not 5-HIAA, is mainly responsible for peak 2, and that changes in the height of this peak reflect changes in the extracellular concentration of uric acid.
D000818:Animals; D001923:Brain Chemistry; D002244:Carbon; D004567:Electrodes, Implanted; D004594:Electrophysiology / Q000295:instrumentation; D005260:Female; D006897:Hydroxyindoleacetic Acid / Q000378:metabolism*; D007211:Indoles / Q000502:physiology*; D008991:Monitoring, Physiologic; D051381:Rats; D011919:Rats, Inbred Strains; D014527:Uric Acid / Q000378:metabolism*
D007211:Indoles; D014527:Uric Acid; C026785:5-hydroxyindole; D006897:Hydroxyindoleacetic Acid; D002244:Carbon