OPRM1 and major depressive disorder: Except for the receptors of three signaling peptides: corticotropin-releasing hormone (CRHR1), gastrin-releasing peptide (GRPR), and bile acid (GPBAR1), all other dysregulated peptide GPCRs in MDD were shared with SCZ: FPR2, GALR3, HCAR2, MAS1, MC2R, MC5R, NMUR2, NPY1R and NPY6R, OPRM1, relaxin RXFP3, and TACR3.