Figure 3. . Cerebrospinal fluid levels of kynurenines in suicide attempters and healthy volunteers.

Levels of (A) tryptophan, (B) kynurenine, (C) nicotinamide, (D) 3-hydroxykynurenine, (E) quinolinic acid, (F) picolinic acid, (G) kynurenic acid, (H) ratio of kynurenine/tryptophan and (I) ratio of picolinic acid/quinolinic acid in the CSF of suicide attempters and healthy controls. Each point represents the concentration of a single CSF sample in units of nM and mean is displayed in all graphs but for tryptophan concentration where the unit is in μM. Statistical differences between healthy controls and suicide attempters are determined using two-tailed Mann–Whitney test, *p < 0.05.

CSF: Cerebrospinal fluid; KYNA: Kynurenic acid; PIC: Picolinic acid; QUIN: Quinolinic acid.