Oxytocin (medication)
Oxytocin, sold under the brand name Pitocin among others, is a medication made from the peptide "oxytocin". As a medication, it is used to cause contraction of the uterus to start labor, increase the speed of labor, and to stop bleeding following delivery. For this purpose, it is given by injection either into a muscle or into a vein.
The use of oxytocin as a medication can result in excessive contraction of the uterus that can risk the health of the baby. Common side effects in the mother include nausea and a slow heart rate. Serious side effects include rupture of the uterus and with excessive dose, water intoxication. Allergic reactions including anaphylaxis may also occur.
Oxytocin was discovered in 1952. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. , the wholesale cost in the developing world is US$0.10 to 0.56 per dose.Oxytocin injection (synthetic) is contraindicated in any of these conditions:Oxytocin is relatively safe when used at recommended doses, and side effects are uncommon. These maternal events have been reported:Excessive dosage or long-term administration (over a period of 24 hours or longer) has been known to result in tetanic uterine contractions, uterine rupture, postpartum hemorrhage, and water intoxication, sometimes fatal.
Neuroendocrinology
Oxytocin and vasopressin (also called anti-diuretic hormone), the two neurohypophysial hormones of the posterior pituitary gland (the neurohypophysis), are secreted from the nerve endings of magnocellular neurosecretory cells into the systemic circulation. The cell bodies of the oxytocin and vasopressin neurons are in the paraventricular nucleus and supraoptic nucleus, respectively, and the electrical activity of these neurons is regulated by afferent synaptic inputs from other brain regions. By contrast, the hormones of the anterior pituitary gland (the adenohypophysis) are secreted from endocrine cells that, in mammals, are not directly innervated, yet the secretion of these hormones (adrenocorticotrophic hormone, luteinizing hormone, follicle-stimulating hormone, thyroid-stimulating hormone, prolactin, and growth hormone) remains under the control of the hypothalamus. The hypothalamus controls the anterior pituitary gland via "releasing factors" and "release-inhibiting factors"; these are blood-borne substances [author means via bloodstream and not by the lymphatic system nor air, nor any other modes of transport] released by hypothalamic neurons into blood vessels at the base of the brain, at the median eminence. These vessels, the hypothalamo-hypophysial portal vessels, carry the hypothalamic factors to the anterior pituitary, where they bind to specific receptors on the surface of the hormone-producing cells.