Thus, in addition to GalR1 and 5-HT1A receptor heterodimers (Borroto-Escuela et al., 2010), the galanin (1–15) fragment alone induces strong depression- and anxiogenic-related effects and may regulate mood via binding to GalR1 and GalR2 heterocomplexes (Millon et al., 2014, 2017a,b). This evidence concerns the gene GAL and major depressive disorder.