Original article
The level of kynurenic acid and selected cytokines during antidepressive treatment

Changes in the kynurenic pathway and pro-inflammatory cytokines seem to play a role in the development and course of depressive disorders. It is assumed that cytokines may influence the pathway of changes of kynurenine in the direction of synthesis of toxic metabolites. In the study we attempted to evaluate whether there are any differences in the concentrations of kynurenic acid (KYNA), tumor necrosis factor α (TNF-α) and interleukin 6 (IL-6) in the blood serum of patients diagnosed with major depression and tried to determine the influence of the applied treatment on the levels of those concentrations.

Material and methods: KYNA level was assessed by means of high-performance liquid chromatography (HPLC). MADRS and CGI scales were used to assess mental state. Thirty patients with an episode of major depression were examined according to ICD-10.

Results: Significantly lower values of KYNA can be observed in the blood serum of the patients with an episode of major depression as compared to the healthy group. The same patients do not have significantly changed values of TNF-αand IL-6 cytokines before treatment. No significant changes in the levels of KYNA and cytokines take place after the application of treatment in spite of clinical improvement.

Conclusions: The level of KYNA in the blood serum of patients with a major depression episode may be a more sensitive marker than the cytokine levels.