Vincent du Vigneaud (1901–1978)
Some 100 years ago, extracts prepared from the posterior pituitary gland were first used to induce labor and stop uterine bleeding after delivery—effects attributed to oxytocin, a drug that continues to be employed for these purposes in childbirth. In 1928, scientists at Parke, Davis & Company separated oxytocin from vasopressin, another hormone in the gland. In 1953, at Cornell Medical College in New York, the American biochemist Vincent du Vigneaud isolated pure oxytocin, which he found contained nine amino acids. For synthesizing the first peptide hormone, du Vigneaud was awarded the 1955 Nobel Prize in Chemistry.
Synthetic oxytocin produces the same effects as the natural hormone. Before childbirth, oxytocin is released from the posterior pituitary gland, a pea-size structure located at the base of the brain. This hormone plays a key role in causing dilation of the uterus (stage 1 of labor) and contraction of the muscles of the uterus, leading to expulsion of the fetus and placenta (stages 2 and 3). To induce labor, oxytocin (Pitocin) is slowly injected intravenously.
Oxytocin is also involved in nursing. During breast-feeding, the infant's suckling stimulates oxytocin release, which causes mammary glands to contract and excrete milk during the “milk let-down” process.
The role of oxytocin in enhancing human sexual behavior remains the subject of scientific inquiry. Some reports suggest that oxytocin levels are elevated and may play a role in the sexual arousal of both men and women and in orgasm in women. Oxytocin may also promote bonding between individuals, mother and baby, and adult couples, increasing trust and decreasing fear.
SEE ALSO Ergotamine and Ergonovine (1925).
The naturally occurring hormone oxytocin is involved in many aspects of maternal behavior, including childbirth and nursing, and it may even promote bonding between mother and baby.