Oxytocin is colloquially referred to as the "bonding hormone." It typically works in conjunction with vasopressin (cys-tyr-phe-gln-asn-csy-pro-arg-gly-NH2) and only differs by two amino acids. Oxytocin and vassopressin are released by the human posterior pituitary gland and are the only known hormones to act at a distance from the brain.
Peripherally it is known to act at the mammary glands causing milk to be "let down" during lactation, in the uterus during the birthing process causing the cervix to dilate and at wound sites by decreasing some cytokines and has been observed to improve wound healing after positive social interactions. Locally, in the brain, it plays a role in sexual arousal, social bonding, maternal behavior and romantic attachment.
It has been theorized that in its reduced form, oxytoceine, it may act as a free radical scavenger, donating electrons to free radicals, making them more stable and therefore less likely to cause biological harm. Synthetic oxytocin has been used to induce labor and it has been suggested that it might help people who suffer from social anxieties, mood disorders and autism. Almost all vertebrates have an oxytocin-like hormone.