The OXTR protein belongs to the G-protein coupled receptor family and acts as a receptor for oxytocin. Its activity is mediated by G proteins which activate several different second messenger systems.Oxytocin receptors are expressed by the myoepithelial cells of the mammary gland, and in both the myometrium and endometrium of the uterus at the end of pregnancy. The oxytocin-oxytocin receptor system plays an important role as an inducer of uterine contractions during parturition and of milk ejection.Oxytocin receptors are also present in the central nervous system. These receptors modulate a variety of behaviors, including stress and anxiety, social memory and recognition, sexual and aggressive behaviors, bonding (affiliation) and maternal behavior.