Differences in Kynurenine Metabolism During Depressive, Manic, and Euthymic Phases of Bipolar Affective Disorder

Author(s): Alexander Maget, Martina Platzer*, Susanne A. Bengesser, Frederike T. Fellendorf, Armin Birner, Robert Queissner, Carlo Hamm, Bernd Reininghaus, Andrzej Hecker, Lukas Tomberger, Renè Pilz, Nina Dalkner, Natalie Moll, Gregor Schütze, Markus Schwarz, Hans P. Kapfhammer, Eva Z. Reininghaus.

Journal Name: Current Topics in Medicinal Chemistry

Volume 20 , Issue 15 , 2020

Become EABM
Become Reviewer

Graphical Abstract:


Background & Objective: The kynurenine pathway is involved in inflammatory diseases. Alterations of this pathway were shown in psychiatric entities as well. The aim of this study was to determine whether specific changes in kynurenine metabolism are associated with current mood symptoms in bipolar disorder.

Methods: Sum scores of the Hamilton Depression Scale, Beck Depression Inventory, and Young Mania Rating Scale were collected from 156 bipolar individuals to build groups of depressive, manic and euthymic subjects according to predefined cut-off scores. Severity of current mood symptoms was correlated with activities of the enzymes kynurenine 3-monooxygenase (ratio of 3-hydroxykynurenine/ kynurenine), kynurenine aminotransferase (ratio of kynurenic acid/ kynurenine) and kynureninase (ratio of 3-hydroxyanthranilic acid/ 3-hydroxykynurenine), proxied by ratios of serum concentrations.

Results: Individuals with manic symptoms showed a shift towards higher kynurenine 3-monooxygenase activity (χ2 = 7.14, Df = 2, p = .028), compared to euthymic as well as depressed individuals. There were no differences between groups regarding activity of kynurenine aminotransferase and kynureninase. Within the group of depressed patients, Hamilton Depression Scale and kynurenine aminotransferase showed a significant negative correlation (r = -0.41, p = .036), displaying lower metabolism in the direction of kynurenic acid.

Discussion: Depression severity in bipolar disorder seems to be associated with a decreased synthesis of putative neuroprotective kynurenic acid. Furthermore, higher kynurenine 3-monooxygenase activity in currently manic individuals indicates an increased inflammatory state within bipolar disorder with more severe inflammation during manic episodes. The underlying pathophysiological mechanisms of the different affective episodes could represent parallel mechanisms rather than opposed processes.

Keywords: Bipolar disorder, Kynurenine, Pteridines, Inflammation, Mood, Depression, Mania.

Rights & PermissionsPrintExport Cite as

Article Details

Year: 2020
Page: [1344 - 1352]
Pages: 9
DOI: 10.2174/1568026619666190802145128
Price: $65

Article Metrics

PDF: 11