The new ‘5-HT’ hypothesis of depression: Cell-mediated immune activation induces indoleamine 2,3-dioxygenase, which leads to lower plasma tryptophan and an increased synthesis of detrimental tryptophan catabolites (TRYCATs), both of which contribute to the onset of depression
Michaël Maes, B. E. Leonard, Aye-Mu Myint, et al.·2010·Progress in Neuro-Psychopharmacology and Biological Psychiatry