Simultaneous depletion of tryptophan, tyrosine and phenylalanine as an experimental method to probe brain monoamine function in humans

Pradeep J. Nathan, Jay-Maree Hughes, Bernie McInerney, Ben J. Harrison

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Brain monoamines are important regulators of affective and cognitive processes and are involved in the aetiology of a number of psychiatric disorders. While methods to probe serotonin and catecholamine function are established, limited methods are available to probe monoamine function as a whole in humans. In the current study, we examined if simultaneous depletion of monoamine precursors can be used as a possible probe of monoamine function. Ten healthy subjects were tested under two treatment conditions; balanced control (B) condition and combined monoamine depletion (CMD) condition. Monoamine precursor depletion was associated with significant reductions in plasma-free tryptophan (46%), tyrosine (74%) and phenylalanine (78%). Greater reductions were achieved for ratios of each precursor to other large neutral amino acids (LNAA); tryptophan/LNAA (86%), tyrosine/LNAA (94%) and phenylalanine/LNAA (94%). Findings suggest that simultaneous depletion of monoamine precursors can achieve significant plasma monoamine depletion in the range expected to affect brain monoamine function.
Original languageEnglish
Pages (from-to)171-176
Number of pages6
JournalInternational Journal of Neuropsychopharmacology
Volume7
Issue number2
DOIs
Publication statusPublished - 2004

Keywords

  • dopamine
  • monoamine depletion
  • serotonin
  • tryptophan
  • tyrosine

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