Currently, there has been only one OXT receptor identified (Gimpl and Fahrenholz, 2001), and it is located in abundance throughout both central and peripheral systems. The OXT receptor (OXTR) is a member of the family of the rhodopsin-type 1 G protein-coupled receptor (GPCR) family and, together with three vasopressin receptor subtypes (V1a, V1b and V2), forms a subfamily of structurally related receptors (Devost et al., 2008). Centrally, OXTRs are typically abundant in brain areas that regulate social and emotional behaviors and reward, such as PFC, ventral tegmental area (VTA), NAc, caudate putamen (CPu), lateral septum (LS), hippocampus, hypothalamus, ventral pallidum (VP), bed nucleus of the stria terminalis (BNST), amygdala, and brainstem (Freeman and Young, 2016). However, expression of OXTR within the CNS is highly variable, even within species and expression patterns appear to be related to a number of factors including gonadal hormones, early life experience as well as functional and adaptive patterns of sociality and aggression (Dumais and Veenema, 2016, Carter, 2017). Sex-related differences in OXTR binding density have been identified in multiple brain regions (NAc, dorsal CPu, LS,
