Oksütotsiini

Oksütotsiini, or oxytocin, is a peptide hormone and neuropeptide essential for reproduction and social behavior. It is produced by magnocellular neurons in the hypothalamus (paraventricular and supraoptic nuclei) and released into the bloodstream from the posterior pituitary; within the brain it also acts as a neurotransmitter and neuromodulator.

Chemically, oxytocin is a nine-amino-acid cyclic peptide linked by a disulfide bond; its receptor, oxytocin receptor (OXTR), is a G protein-coupled receptor expressed in the uterus, mammary glands, brain, and other tissues.

Physiological roles: Peripherally, oxytocin stimulates uterine smooth muscle contractions during labor and promotes milk ejection from the mammary glands. It also supports postpartum uterine involution. Centrally, it influences social bonding, maternal behaviors, pair bonding, trust, and stress regulation; evidence is still evolving regarding its role in human social deficits.

Clinical uses: Oxytocin is used medically to induce or augment labor and to prevent or treat postpartum hemorrhage. It is administered intravenously or intramuscularly; intranasal formulations are used in some settings or in research. Pharmacological effects include risks of uterine hyperstimulation, fetal distress, and water retention leading to hyponatremia; care is required in certain conditions.

History and pharmacokinetics: The structure was elucidated in the 1950s by Vincent du Vigneaud, who won the Nobel Prize for peptide hormone work. The circulating half-life of oxytocin is short, and while its peripheral actions are well known, its central effects are mediated by its action as a brain neuromodulator; intranasal delivery is studied for effects on social behavior.