The urinary excretion of tryptophan and tryptophan metabolites in the chronic ethanol-fed rat.
An investigation was made into the hypothesis that chronic ethanol ingestion disturbs the metabolism of tryptophan which is reflected by alterations in the urinary excretion of the metabolites 5-hydroxyindoleacetic acid (5-HIAA), anthranilic acid (AA) and indoleacetic acid (IAA). In particular, we investigated whether experimental chronic alcoholism is associated with a decrease in the tryptophan metabolite ratios as suggested in the literature. Male Wistar rats were chronically fed a nutritionally-complete liquid diet in which ethanol comprised 35% of total calories: controls were pair-fed identical amounts of the same diet in which ethanol was replaced by isocaloric glucose. At 6 weeks, 24 h urine samples were collected for the analysis of tryptophan, 5-HIAA, AA and IAA by HPLC. During ethanol-feeding there were reductions in the daily urinary excretion (i.e. mumol/24 h) of tryptophan (-57%, P = 0.026) and concomitant increases in 5-HIAA excretion (62%, P = 0.057). Expression of data in terms of lean tissue mass (i.e. urinary creatinine) revealed identical conclusions. An analysis was performed on the molar ratios of these urinary analytes. The tryptophan: total metabolite ratio was significantly decreased (by -53%), but the AA: total metabolite ratio was not significantly altered (P = 0.102). The ratios 5-HIAA/AA and 5-HIAA/IAA were slightly increased, but they did not attain statistical significance (P > 0.351). It was concluded that chronic ethanol feeding is associated with significant changes in the urinary excretion of tryptophan and its related metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)
Bonner
A B
AB
Addictive Behaviour Centre, Roehampton Institute, London, UK.
Brien
S
S
Preedy
V R
VR
D000437:Alcoholism / Q000378:metabolism / Q000652:urine*; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004032:Diet; D000431:Ethanol / Q000494:pharmacology*; D006897:Hydroxyindoleacetic Acid / Q000652:urine; D007210:Indoleacetic Acids / Q000652:urine; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000378:metabolism / Q000652:urine*; D062367:ortho-Aminobenzoates / Q000652:urine
D007210:Indoleacetic Acids; D062367:ortho-Aminobenzoates; D000431:Ethanol; D006897:Hydroxyindoleacetic Acid; D014364:Tryptophan