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.
Supraoptic nucleus
Vasopressin neurons and oxytocin neurons make many other neuroactive substances in addition to vasopressin and oxytocin, though most are present only in small quantities. However, some of these other substances are known to be important. Dynorphin produced by vasopressin neurons is involved in regulating the phasic discharge patterning of vasopressin neurons, and nitric oxide produced by both neuronal types is a negative-feedback regulator of cell activity. Oxytocin neurons also make dynorphin; in these neurons, dynorphin acts at the nerve terminals in the posterior pituitary as a negative feedback inhibitor of oxytocin secretion. Oxytocin neurons also make large amounts of cholecystokinin as well as the cocaine and amphetamine regulatory transcript (CART).