GRM2 and depressive disorder: As the receptor of the neurotransmitter glutamate, mGluR2/3 is distributed in brain regions which are linked to social behavior and emotion regulation, such as the prefrontal cortex (PFC), anterior cingulate cortex, thalamus, amygdala and hippocampus (Matosin et al. 2014; Wright et al. 2001), indicating a modulatory role in depression.