Oxytocin
Oxytocin (Oxt) is a peptide hormone and neuropeptide. Oxytocin is normally produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, sexual reproduction, childbirth, and the period after childbirth. Oxytocin is released into the bloodstream as a hormone in response to stretching of the cervix and uterus during labor and with stimulation of the nipples from breastfeeding. This helps with birth, bonding with the baby, and milk production. Oxytocin was discovered by Henry Dale in 1906. Its molecular structure was determined in 1952. Oxytocin is also used as a medication to facilitate childbirth.
Marinus van IJzendoorn
In humans, oxytocin has been shown to be associated with delivery, mood regulation, sexual functioning and parenting behaviours. Emerging studies are showing an increasing link between oxytocin levels in humans and parent-child relationships. One idea is that increased oxytocin levels facilitates postnatal parental behaviour and the formation of an emotional bond between parent and infant, in mothers and fathers alike, by acting to reduce anxiety and ameliorate responses to external stresses. Parents who have a less anxious state of mind are able to increase their focus on infant care, improve mood, and facilitate the capacity to read non-verbal infant cues and stimulate the social learning and reward system in response to infant cues. Although there are strong animal models for the role of oxytocin in parental behaviour, one of the key questions in the development of a psychobiology of human care-giving and attachment is the degree to which the considerable variation in parenting can be accounted for through similar biological mechanisms such as the moderating role of the oxytocin receptor gene (OXTR) polymorphisms and experimentally induced oxytocin levels.
Van IJzendoorn and colleagues conducted several correlational studies documenting the role of OXTR in parenting, and carried out various randomized control trials showing that oxytocin enhances male and female sensitivity to child signals, in natural play settings as well as with a cry test, using behavioural assessments, EEG/ERP, and fMRI. A meta-analysis of experimental studies with intranasal oxytocin administration was conducted showing that feelings of trust are elevated and that the expected lowering of out-group trust was not confirmed.