Occurrence in vivo of 5-hydroxytryptophol in the brain of rats treated with ethanol

The effect of ethanol (EtOH) on the release of dopamine (DA) and 5-hydroxytryptamine (5-HT) and the efflux of their metabolites, 3,4-dihydroxyphenylacetic acid (DOPAC), 5-hydroxyindol-3-ylacetic acid (5-HIAA) and 5-hydroxytryptophol (5-HTOL) from the striatum of the freely moving rat were studied in vivo using brain microdialysis. Striatal DA and 5-HT release was maximally enhanced at first fraction after the administration of EtOH (2 g/kg, i.p.). The level of the DA-oxidized metabolite, DOPAC, decreased significantly. In the 5-HT metabolic pathway, the oxidized metabolite, 5-HIAA, did not show significant changes, whereas levels of the biogenic alcohol 5-HTOL were increased to 180% at 90 min following EtOH administration. It is suggested that EtOH, most probably via acetaldehyde, could shift 5-HT metabolism from the oxidative to the reductive pathway in the rat brain.