Altered tryptophan catabolite concentrations in major depressive disorder and associated changes in hippocampal subfield volumes

The kynurenine pathway (KP) is the major metabolic pathway for tryptophan in the body resulting in the production of kynurenine (KYN) and several downstream metabolites (O ’Farrell and Harkin et al., 2017; Stone et al., 2013). Induction of the rate limiting enzyme in the KP, indolamine 2,3 dioxygenase (IDO) is driven by inflammatory cytokines which has been proposed as a mechanism by which inflammation can precipitate depressive symptoms via tryptophan depletion. Mo st particularly activation of the KP and tryptophan depletion has been observed in depression that occurs secondary to exogenous administration of the cytokines IFN-alpha and IL-2 (Raison et al., 2010).

Source: Psychoneuroendocrinology - May 15, 2018 Category: Psychiatry Authors: Kelly Doolin, Kelly A. Allers, Sina Pleiner, Andre Liesener, Chloe Farrell, Leonardo Tozzi, Erik O ’Hanlon, Darren Roddy, Thomas Frodl, Andrew Harkin, Veronica O’Keane Source Type: research