Oxytocin Topics

• nobel prize in chemistry
• oxytocin receptor
• g protein coupled receptors
• stria terminalis
• corticotropin releasing hormone
• g protein coupled receptor
• bed nucleus
• paraventricular nucleus
• protein coupled receptors
• nerve terminals
• maternal behaviors
• vincent du vigneaud
• nerve endings
• dynorphin
• neurohypophysis
• cysteine residues
• social recognition
• vasopressin
• exocytosis

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Oxytocin, Oxytocin

Recent studies have begun to investigate oxytocin's role in various behaviors, including orgasm, social recognition, pair bonding, anxiety, trust, love, and maternal behaviors.

It is then released into the blood from the posterior lobe (neurohypophysis) of the pituitary gland. Oxytocin is also made by some neurons in the paraventricular nucleus that project to other parts of the brain and to the spinal cord. Depending on the species, oxytocin-expressing cells are located in other areas, including the amygdala and bed nucleus of the stria terminalis. It is postulated that trusting behavior is somehow influenced by these oxytocin stimulated neurons.

These cells generate action potentials that propagate down axons to the nerve endings in the pituitary; the endings contain large numbers of oxytocin-containing vesicles, which are released by exocytosis when the nerve terminals are depolarised.

The sequence is cysteine - tyrosine - isoleucine - glutamine - asparagine - cysteine - proline - leucine - glycine (CYIQNCPLG). The cysteine residues form a sulfur bridge. Oxytocin has a molecular mass of 1007 dalton. One international unit (IU) of oxytocin is the equivalent of about 2 micrograms of pure peptide.

A table showing the sequences of members of the vasopressin/oxytocin superfamily and the species expressing them is present in the vasopressin article. Oxytocin and vasopressin were isolated and synthesized by Vincent du Vigneaud in 1953, work for which he received the Nobel Prize in Chemistry in 1955.

However, oxytocin neurons make other peptides, including corticotropin-releasing hormone (CRH) and dynorphin, for example, that act locally. The magnocellular neurons that make oxytocin are adjacent to magnocellular neurons that make vasopressin, and are similar in many respects.

The oxytocin receptor is a G-protein-coupled receptor which requires Mg 2+ and cholesterol. It belongs to the rhodopsin-type (class I) group of G-protein-coupled receptors.

At least two non-controlled studies have found increases in plasma oxytocin at orgasm in both men and women.

Oxytocin receptors are expressed by neurons in many parts of the brain and spinal cord, including the amygdala, ventromedial hypothalamus, septum and brainstem.

Oxytocin is destroyed in the gastrointestinal tract, and therefore must be administered by injection or as nasal spray. Oxytocin has a half-life of typically about three minutes in the blood. Oxytocin given intravenously does not enter the brain in significant quantities - it is excluded from the brain by the blood-brain barrier. There is no evidence for significant CNS entry of oxytocin by nasal spray. Oxytocin nasal sprays have been used to stimulate breastfeeding but the efficacy of this approach is doubtful.

It has largely replaced ergometrine as the principal agent to increase uterine tone in acute postpartum haemorrhage. Oxytocin is also used in veterinary medicine to facilitate birth and to increase milk production. The tocolytic agent atosiban ( Tractocile ) acts as an antagonist of oxytocin receptors; this drug is registered in many countries to suppress premature labour between 24 and 33 weeks of gestation. It has fewer side-effects than drugs previously used for this purpose (ritodrine, salbutamol and terbutaline).Some have suggested that the trust-inducing property of oxytocin might help those who suffer from social anxieties and mood disorders, while others have noted the potential for abuse with confidence tricks.

Source: Wikipedia > Oxytocin