/ok'si toh"seuhn/, n.
1. Biochem. a polypeptide hormone, produced by the posterior lobe of the pituitary gland, that stimulates contraction of the smooth muscle of the uterus.
2. Pharm. a commercial form of this substance, obtained from beef and hog pituitary glands or esp. by synthesis, and used chiefly in obstetrics to induce labor and to control postnatal hemorrhage.
[1925-30; OXYTOC(IC) + -IN2]

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      hormone used clinically to help begin or to continue labour, to control bleeding following delivery, and to stimulate the secretion of breast milk. Oxytocin was first synthesized (along with the related antidiuretic hormone [ADH]) by Vincent du Vigneaud (du Vigneaud, Vincent) in 1953, and he received the Nobel Prize for Chemistry in 1955 for this work. Synthetic oxytocin has since become widely used in obstetric practice.

      Natural oxytocin is secreted by the posterior pituitary gland, which holds and secretes oxytocin produced by the hypothalamus. Oxytocin causes milk to be ejected from the breasts during lactation; the amount of oxytocin produced naturally, however, has little effect on uterine contractions and does not stimulate labour. When synthetic oxytocin is infused in larger amounts, however, it causes smooth muscle in the wall of the uterus to contract and initiate the process of labour. Smooth-muscle cells in the uterus contain proteins that bind specifically to oxytocin; the number of these oxytocin receptors increases during late pregnancy. Oxytocin's effect on uterine smooth muscle is dependent on the presence of estrogen, and for that reason oxytocin has little effect on the uterus during the early stages of pregnancy; near term, however, it is very effective and successfully produces uterine contractions in 80–90 percent of the women to whom it has been administered.

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Universalium. 2010.

Look at other dictionaries:

  • Oxytocin — Systematic (IUPAC) name 1 ({(4R,7S,10S …   Wikipedia

  • Oxytocin — Strukturformel …   Deutsch Wikipedia

  • Oxytocin — Oxytocin, vom Hypothalamus gebildetes und in der Neurohypophyse gespeichertes ⇒ Neurohormon der Säuger; ein durch eine Disulfidbrücke ringförmig geschlossenes Nonapeptid; es bewirkt eine Kontraktion der Uterusmuskulatur, löst Wehen aus und führt… …   Deutsch wörterbuch der biologie

  • oxytocin — [äk΄si tō′sin, äk΄sitäs′in] n. [< OXYTOCIC + IN1] a hormone, C43H66N12O12S2, of the posterior pituitary gland, that stimulates contractions in the smooth muscle of the uterus and facilitates the secretion of milk: cf. NEUROHYPOPHYSIS …   English World dictionary

  • Oxytocin — A hormone made in the brain that plays a role in childbirth and lactation by causing muscles to contract in the uterus (womb) and the mammary glands in the breast. Animal studies have shown that oxytocin also has a role in pair bonding, mate… …   Medical dictionary

  • Oxytocin — O|xy|to|cin [↑ Ox (1); griech. tókos = Geburt; ↑ in (3)], das; s, e; S: Oxytozin: ein im Hypothalamus gebildetes, eine Disulfidbrücke enthaltendes ↑ Peptid Hormon aus 9 Aminosäuren, MG 1007, das mit Melanoliberin u. Melanostatin verwandt ist. Im… …   Universal-Lexikon

  • oxytocin — n. a hormone, released by the pituitary gland, that causes contraction of the uterus during labour and stimulates milk flow from the breasts by causing contraction of muscle fibres in the milk ducts. Intravenous infusions or injections of… …   The new mediacal dictionary

  • oxytocin — noun Etymology: International Scientific Vocabulary, from oxytocic Date: 1928 a pituitary octapeptide hormone C43H66N12O12S2 that stimulates especially the contraction of uterine muscle and the secretion of milk …   New Collegiate Dictionary

  • oxytocin — A peptide hormone (1007 D) from hypothalamus: transported to the posterior lobe of the pituitary (see neurophysin). Induces smooth muscle contraction in uterus and mammary glands. Related to vasopressin …   Dictionary of molecular biology

  • oxytocin — noun A hormone that stimulates contractions during labour/labor, and then the production of milk. See Also: oxytocic …   Wiktionary

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