IDO1 and Anxiety: In line with clinical findings, experimental studies showed that development of depressive-like and anxiety-like behaviors induced by acute or chronic immune challenges in mice (Frenois et al., 2007; Godbout et al., 2008; Moreau et al., 2008; O'Connor et al., 2009a,b,c; Salazar et al., 2012; Corona et al., 2013; Lawson et al., 2013) is associated with increased peripheral and brain IDO activity (Lestage et al., 2002; Moreau et al., 2005; André et al., 2008).