Zahraa Shamsadeen Omar
Faculty of Pharmacy
Oxytocin is produced in the hypothalamus and is secreted into the bloodstream by the posterior pituitary gland. Secretion depends on electrical activity of neurons in the hypothalamus – it is released into the blood when these cells are excited.
The two main actions of oxytocin in the body are contraction of the womb (uterus) during childbirth and lactation. Oxytocin stimulates the uterine muscles to contract and also increases production of prostaglandins, which increase the contractions further. Manufactured oxytocin is sometimes given to induce labour if it has not started naturally or it can be used to strengthen contractions to aid childbirth. In addition, manufactured oxytocin is often given to speed up delivery of the placenta and reduce the risk of heavy bleeding by contracting the uterus. During breastfeeding, oxytocin promotes the movement of milk through the ducts in the breast, allowing it to be excreted by the nipple. Oxytocin is also present in men, playing a role in sperm transport and production of testosterone by the testes.
In the brain, oxytocin acts as a chemical messenger and has an important role in many human behaviors.
Oxytocin is a hormone that acts on organs in the body (including the breast and uterus) and as a chemical messenger in the brain, controlling key aspects of the reproductive system, including childbirth and lactation, as well as aspects of human behavior (Brownstein et al.).
Control of oxytocin:
Oxytocin production and secretion is controlled by a positive feedback mechanism where release of the hormone causes an action that stimulates more of its own release. For example, when contraction of the uterus starts during childbirth, oxytocin is released. This stimulates more contractions and more oxytocin to be released. In this way, contractions increase in intensity and frequency.
There is also a positive feedback involved in the milk-ejection reflex. Stimulation of the nipple during breastfeeding leads to increased oxytocin production and secretion into the blood, which then causes milk to be let down into the breast. The positive feedback cycle is maintained until the baby stops suckling. The production of oxytocin during childbirth is also self-limiting; release of the hormone is stopped once the baby is delivered.
Problems with Oxytocin Production
High and low oxytocin levels are possible, but research has not yet found any implications of these conditions. Men with high levels of oxytocin sometimes develop benign prostatic hyperplasia, or the enlarging of the prostate gland. This condition can cause urinary complaints. A lack of oxytocin can prevent the milk letdown reflex and make breastfeeding difficult. Low oxytocin levels have also been linked to depression, but using oxytocin to treat mental health conditions has not yet been studied sufficiently.
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Signs and symptoms of oxytocin deficiency
There are a number of symptoms for oxytocin deficiency, including:
Poor communication, an element of irritability and inability to feel affectionate, more anxieties and fears than normal, sexual interactions are more mechanical and fulfill a basic need, difficulty in reaching orgasm, bigger appetite for sugar-rich foods, feeling little joy from life, disturbed sleep, or muscles aches.
Reference:
1.Brownstein MJ, Russell JT, Gainer H (January 1980). “Synthesis, transport, and release of posterior pituitary hormones”. Science. 207 (4429): 373–78.
2.Tsujimoto M, Hattori A (August 2005). “The oxytocinase subfamily of M1 aminopeptidases”. Biochimica et Biophysica Acta (BBA) – Proteins and Proteomics. 1751 (1): 9–18.
3.Repaske DR, Phillips JA, Kirby LT, Tze WJ, D’Ercole AJ, Battey J (March 1990). “Molecular analysis of autosomal dominant neurohypophyseal diabetes insipidus”. The Journal of Clinical Endocrinology and Metabolism. 70 (3): 752–57.
