The metabolism of exogenous 14C-labelled 5-hydroxytryptamine in rats

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Abstract
Hydroxy[1''-C14] tryptamine creatinine sulfate at a dose of 2.9 mg/100 g body weight (1.27 mg of the free base/100 g body weight) was injected subcutaneously into 15 rats. The outstanding feature of metabolism of 5-hydroxytrypta-mine was a rapid elimination of radioactivity within 12 hr.; the radioactivity excreted varied from 36 to 82% of the dose. In all experiments 12-24 hr. urine had a low radioactivity, corresponding to about 4% of the injected dose. Besides 5-hydroxyindolylacetic acid, the major metabolite of 5-hydroxytryptamine, 6 radioactive compounds of unknown structure were found in 12 hr. urine. All of them gave a positive test with Ehrlich''s reagent and 2 of them are believed to be glucuronides. A small amount of unchanged 5-hydroxy[1''-C14]tryptamine was recovered in urine. The synthesis and properties of 5-hydroxyindolylaceturic acid are described. This compound was not detected as a metabolite of 5-hydroxytryptamine in rats.
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