DRD2 and Anxiety: Naïve Grp-/- mice displayed normal anxiety and pain sensitivity (Supplementary Fig. 3 and 5), consistent with normal expression of immediate-early genes (IEG; c-Fos and Arc; Supplementary Fig. 4) and dopamine-related genes (Drd1, Drd2, Th and Nurr1; Supplementary Fig. 9) in the BLA and VTA of naïve Grp-/- mice.