Urinary Excretion of Tryptamine in Comparison to Normetanephrine and Beta-Phenylethylamine in Human Volunteers After Subchronic Treatment with Different Monoamine Oxidase Inhibitors
Measurement of urinary tryptamine excretion has been used extensively in the past as indicator for monoamine oxidase (MAO) inhibition in man. Basal tryptamine excretion (ug/g creatinine) differs between sexes (p< 0.001). The values obtained (x ± SD) were: 66 ± 26 in 13 males (n = 90) and 112 ± 42 in 9 females (n = 60). The higher basal tryptamine excretion and the larger tryptamine/indole acetic acid ratios in females, together with the greater effect of MAO inhibitors suggest a lower basal MAO-A activity in women. Different hormonal influences could explain the large interindividual and intraindividual seasonal variation of tryptamine excretion in females. By comparison of urinary tryptamine, normetanephrine and beta-phenylethylamine during subchronic treatment with three different MAO inhibitors it could be shown that tryptamine is a MAO-A substrate. MAO-A inhibition by the new reversible selective inhibitor CGP 11 305 A (150mg/d) caused parallel increases of tryptamine (320%) and normetanephrine (360%), but did not change urinary phenylethylamine. Selective MAO-B inhibition with deprenyl (10mg/d) enhanced phenylethylamine excretion (2600%), but did not affect tryptamine. During treatment with tranylcypromine (20mg/d), the unspecific inhibitor of both MAO-A+B, all three metabolites increased significantly (between 440% and 720%).
KeywordsPlacebo Creatinine Tryptophan Oestradiol Indole
Unable to display preview. Download preview PDF.
- Baker, G. B., Calverley, D. G., Dewhurst, W. G. and Martin I. L. (1979) A sensitive gas chromatographic technique for quantification of urinary tryptamine. Br. J. Pharmacol. 67, 469 P.Google Scholar
- Bieck, P., Antonin, K.H., and Jedrychowski, M. (1983) Monoamine oxidase inhibition in healthy volunteers by CGP 11 305 A, a new specific inhibitor of MAO-A. Mod. Probl. Pharmacopsychiat. 19, 53–62.Google Scholar
- Cremer, G., Antonin, K. H. and Bieck, P. (1983) Monoamine oxidase inhibition in healthy volunteers by (-)deprenyl (D). Naunyn-Schmiedeberg’s Arch. Pharmacol. 322, Suppl. R 132.Google Scholar
- Lauber, J. and Waldmeier, P. C. (1983) In preparation. Biol. Med. 109, 225–227.Google Scholar
- Murphy, D. L., Cohen, R. M., Siever, L. J., Roy, B., Karoum, F., Uyatt, R. J., Garrick, N. A. and Linnoila, M. (1983) Clinical and laboratory studies with selective monoamine-oxidase-in- hibiting drugs. Mod. Probl. Pharmacopsychiat. 19, 287–303.Google Scholar
- Nilsson, E. and Hengen, N. (1983) Measurement of indole-3-acetic acid in human urine by HPLC-UV. In preparation.Google Scholar
- Nilsson, E. and Schick, Ch. (1983) Effect of different monoamine oxidase (MAO) inhibitors on human urinary tryptamine excretion. Naunyn-Schmiedeberg1s Arch. Pharmacol. 322, Suppl. R 133.Google Scholar
- Waldmeier, P. C., Baumann, P. A., Delini-Stula, A., Bernasconi, R., Sigg, K., Buech, O., Felner, A. E. (1983a) Characterization of a new, short-acting and specific inhibitor of type A monoamine oxidase. Mod. Probl. Pharmacopsychiat. 19, 31–52.Google Scholar
- Waldmeier, P. C., Antonin, K. H., Feldtrauer, J. J. Grunenwald, Ch., Paul, E., Lauber, J. and Bieck, P. (1983b) Urinary excretion of o-methylated catecholamines, and phenylethylamine in human volunteers treated with tranylcypromine and CGP 11 305 A. Eur. J. Clin Pharmacology, in print.Google Scholar
- White, H. L. and Tansik, R. L. (1979) Characterization of multiple substrate binding sites of MAO, in Monoamine oxidases: structure, function and altered functions ( Singer, Van Korff, Murphy, eds.) pp. 129–144. Academic Press, New York.Google Scholar
- Youdim, M. B. H. and Finberg, J. P. M. (1933) Monoamine oxidase inhibitor antidepressants, in Psychopharmacology Part I: Preclinical Psychopharmacology ( GrahameSmith, Cowen, eds.) pp. 38–70. Excerpta Medica, Amsterdam.Google Scholar