HTR1A and Anxiety: In fact, the parallel presence of increased anxiety-like and anti-depressive-like responses in the FST was previously seen in 5-HT1A receptor deficient mice (Heisler et al., 1998) and in mice lacking the CB1 receptor in cortical glutamatergic neurons (Glu-CB1−/−; Steiner et al., 2008; Jacob et al., 2009; Häring et al., 2011, 2012, 2013).