GRM2 and Anxiety: An anxiolytic effect of mGlu2/3 agonists has been demonstrated in a number of rodent anxiety paradigms [e.g. elevated plus maze (Linden et al., 2005); fear potentiated startle (Helton et al., 1998); lactate-induced panic (Shekhar and Keim, 2000)], and confirmed in healthy human volunteers in the fear potentiated startle test (Grillon et al., 2003), in panic disorder patients exposed to CO2-induced anxiety (Schoepp et al., 2003) and in patients with general anxiety disorder (Dunayevich et al., 2008).