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.
L-368,899
L-368,899 is a drug used in scientific research which acts as a selective antagonist of the oxytocin receptor, with good selectivity over the related vasopressin receptors. Unlike related drugs such as the peripherally selective L-371,257, the oral bioavailabity is high and the brain penetration of L-368,899 is rapid, with selective accumulation in areas of the limbic system. This makes it a useful tool for investigating the centrally mediated roles of oxytocin, such as in social behaviour and pair bonding, and studies in primates have shown L-368,899 to reduce a number of behaviours such as food sharing, sexual activity and caring for infants, demonstrating the importance of oxytocinergic signalling in mediating these important social behaviours.