Oxytocin

Oxytocin is a peptide hormone and neuropeptide that plays a crucial role in social bonding, sexual reproduction in both sexes, and during and after childbirth. It is released in large amounts after distension of the cervix and uterus during labor, facilitating birth, maternal bonding, and, after stimulation of the nipples, lactation. Both childbirth and milk ejection result from positive feedback mechanisms.

Structure and relation to vasopressin

Oxytocin is a peptide of nine amino acids (a nonapeptide). Its systematic name is cysteine-tyrosine-isoleucine-glutamine-asparagine-cysteine-proline-leucine-glycine-amine (cys – tyr – ile – gln – asn – cys – pro – leu – gly – NH2, or CYIQNCPLG-NH2). The cysteine residues form a disulfide bond. Oxytocin has a molecular mass of 1007 daltons. One international unit (IU) of oxytocin is the equivalent of about 2 micrograms of pure peptide.

Function

Oxytocin is known to be involved in a wide variety of physiological and pathological functions such as sexual activity, penile erection, ejaculation, pregnancy, uterine contraction, milk ejection, maternal behavior, social bonding, stress and probably many more, which makes oxytocin and its receptor potential candidates as targets for drug therapy.

History

The word oxytocin was coined from the term oxytocic, Greek for "quick birth", after its uterine-contracting properties were discovered by British pharmacologist Sir Henry Hallett Dale in 1906. The hormone was found to be produced in the hypothalamus and released into circulation through the posterior pituitary gland.

See also

• Vasopressin
• Pitocin
• Posterior pituitary

References

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  Oxytocin 3D structure from NMR solution

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  The biosynthesis of the different forms of oxytocin

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