Summary. The protein encoded by this gene belongs to the G-protein coupled receptor family and acts as a receptor for oxytocin. Its activity is mediated by G proteins which activate a phosphatidylinositol-calcium second messenger system.The oxytocin-oxytocin receptor system plays an important role in the uterus during parturition. The relations between OXTR and loneliness were examined, as well as interactions between OXTR and sex, parental support, 5-HTTLPR genotype, and DRD2 genotype. 2  Initial evidence that the capacity to respond to suggestions for altered internal experience (hypnosis) is influenced by the oxytocin receptor gene.