Oxytocin, motherhood and bonding.

Release of the peptide hormone oxytocin in the brain has been shown to influence both maternal, sexual and social bonding behaviours although there are a number of species differences. This review summarizes findings on the distributions of oxytocin and oxytocin receptors in the brain, together with factors governing their expression, release of the peptide in the brain and its behavioural actions. A model of how oxytocin may act to alter maternal and socio-sexual behaviours is proposed which initially involves activation of oxytocin neurones in a single brain site, the paraventricular nucleus of the hypothalamus (PVN), following vaginal and cervical stimulation. This causes a co-ordinated release of the peptide in the PVN and its terminal projection regions for up to 1 h and this promotes different behavioural components, primarily through modulation of classical transmitter systems.