Tryptophan Metabolism in Post-Withdrawal Alcohol-Dependent Patients

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  1. Gabriele v. Gleissenthall1,
  2. Simon Geisler2,
  3. Peter Malik1,
  4. Georg Kemmler1,
  5. Hannah Benicke1,
  6. Dietmar Fuchs2 and
  7. Sergei Mechtcheriakov1,*
  1. 1Department of Psychiatry and Psychotherapy, Medical University Innsbruck, Anichstr. 35, 6020 Innsbruck, Austria
  2. 2Division of Biological Chemistry, Biocenter, Medical University Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
  1. *Corresponding author: Department of Psychiatry and Psychotherapy, Medical University Innsbruck, Anichstrasse 35, 6020 Innsbruck, Austria. Tel: +43-512-504-23636; Fax: +43-512-504-23855; E-mail: s.mechtcheriakov{at}i-med.ac.at
  • Received December 2, 2013.
  • Revision requested January 29, 2014.
  • Revision received February 13, 2014.
  • Accepted February 18, 2014.

Abstract

Aims: The aim of the study was to investigate the parameters of tryptophan and phenylalanine metabolism and their associations to immune system activation and to behavioural symptoms during medium-term withdrawal (4–12 weeks of abstinence) in alcohol-dependent patients. Methods: Biochemical assays and clinical assessments at the beginning of treatment (fourth week of alcohol abstinence in average) and prior to the discharge after 8 weeks of treatment. Results: Kynurenine to tryptophan ratio (Kyn/Trp) slightly correlated with neopterin levels in early post-withdrawal period (Week 4 of abstinence) but this association disappeared after 12 weeks of abstinence. Phenylalanine and tyrosine concentrations as well as phenylalanine to tyrosine ratio (Phe/Tyr) decreased between Weeks 4 and 12 of abstinence. Kynurenine and Kyn/Trp increased significantly at 12th week of abstinence when compared with the beginning of the study (Week 4 of abstinence). At Week 12, Kyn/Trp significantly correlated with such behavioural symptoms as fatigue, irritability and sleep disturbances. Conclusions: Tryptophan breakdown in early stages may be influenced by the increased activity of indoleamine 2,3-dioxygenase but the increase of Kyn/Trp between Weeks 4 and 12 of abstinence seems to be independent of immune changes and correlates with behavioural symptoms in later stages of the post-withdrawal course. A possible role of kynurenine metabolites in mediation of the increased stress sensibility in post-withdrawal alcohol-dependent patients is discussed.

  1. Alcohol and Alcoholism

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