A study of tryptophan, kynurenine and serotonin transporter in first-episode drug-naïve major depressive disorder. (30th June 2021)

• Record Type: Journal Article
• Authors: Chiu, Yen-Chen; Yang, Bang-Hung; Yang, Kai-Chin; Liu, Mu-N; Hu, Li-Yu; Liou, Ying-Jay; Chan, Li-Yi; Chou, Yuan-Hwa
• Is Part Of: Psychiatry research. Volume 312(2021)
• Publication Date: 2021-06-30
• Subjects: Tryptophan -- Kynurenine -- Serotonin transporter -- Major depressive disorder -- 123I-ADAM -- SPECT; Psychiatry -- Periodicals; Brain -- Imaging -- Periodicals; Psychiatry -- Periodicals; Diagnostic Imaging -- Periodicals; Psychiatrie -- Périodiques; Cerveau -- Imagerie pour le diagnostic -- Périodiques; 616.890754
• DOI: 10.1016/j.pscychresns.2021.111296
• Languages: English
• ISSNs: 0925-4927

Abstract

Highlights: No changes in tryptophan (TRP) concentrations in major depressive disorder (MDD). No changes in kynurenine (KYN) concentrations in first-episode drug-naïve MDD. Decreased KYN/TRP ratio in first-episode drug-naïve MDD. No changes in serotonin transporter (SERT) availability in MDD. Negative association between KYN levels and SERT availably in healthy controls. Abstract: Major depressive disorder (MDD) is associated with the disharmonic functioning of the serotonin system. The serotonin system is mainly modulated by the serotonin transporter (SERT) which regulates serotonin uptake and the metabolism of its precursor, tryptophan and following kynurenine pathway. Currently, there is a lack of research examining both markers concurrently in MDD. This study evaluated the alterations and inter-relationships of both markers in first-episode drug-naïve MDD patients. Thirty-three MDD patients and 33 age- and sex-matched healthy controls (HC) were recruited. The SERT availability were comparable between two groups in the midbrain, thalamus, caudate, and putamen. The kynurenine/tryptophan ratio which indicates tryptophan metabolism was lower in MDD than HC with no group difference in the tryptophan or kynurenine concentration. A negative correlation between the midbrain SERT availability and kynurenine concentration in HC was found. For the subgroup of HC with high kynurenine/tryptophan ratio, the SERT availability was positively associated with the kynurenine/tryptophan ratio and negatively correlated with tryptophan or kynurenine concentration. This study demonstrated the altered tryptophan metabolism and the relationship between tryptophan metabolism and the SERT availability in first-episode drug-naïve MDD patients, which gave a new insight towards the future investigation of the pathophysiology of MDD.