The pituitary gland produces prolactin, which is also known as luteotropic hormone (LTH). This hormone tells the body of a pregnant or nursing woman to produce milk. Prolactin levels may differ in a person's life over a period of time, subject to various factors, such as age and pregnancy. Patients who may be enduring conditions related to anomalous prolactin production can get the level of this hormone in their body tested in medical labs.
Prolactin is produced by the pituitary gland and released in the adenohypophysis, which is located in a structure at the brain's base. This special structure is called the "Turkish saddle".
As the term "lactin" is a Latin term denoting "milk" - a hint that one of the major roles of the hormone prolactin in our body is to promote production of milk. The body begins to produce prolactin in the later phase of pregnancy, making the breasts full of milk just before childbirth. This hormone is produced in women as long as the baby breastfeeds. Oxytocin, another related hormone produced in the pituitary gland, which kindles the let-down reflex, allowing the baby to access mother�s milk.
Nursing mothers have elevated levels of prolactin and this hormone also seems to be associated with menstrual cycle. Several women experience changes in their menstrual cycles during their nursing period and this has been found to be related with prolactin. Moreover, this hormone also plays a role in the eventual termination of menstruation, which happens when a woman is in her menopausal stage. Prolactin is similar to several other hormones that play a part in the reproductive system and it works in tandem with many other hormones in different multifaceted ways. In fact, even now scientists are discovering new aspects of this hormone, especially its manner of functioning in the body.
It appears that this hormone also plays a part in sexual gratification. Prolactin also seems to be involved in progesterone production by corpus luteum. Any alteration in the levels of prolactin can lead to various different conditions, such as galactorrhea, wherein milk production is spontaneous and has no relation whatsoever with pregnancy. Such changes may also result in sterility, infertility and irregular menstrual cycle.
A variety of things are responsible for elevated levels of this hormone in the body. Excessive exercise, tumours in the pituitary gland, and pregnancy may cause the prolactin level in the body to be high. If a physician suspects that his patient may be having difficulty with his/ her pituitary gland, he may ask the patient to undergo a hormone test. The report of a hormone test will enable the physician to appraise all levels of all hormones produced by the pituitary gland. A physician may also ask his patient to undergo a hormone test if the latter is found to be enduring symptoms that may be associated with production of excessive prolactin.
The pituitary gland contains specialized cells called lactotrophs, which are involved in secretion of prolactin. At times, lactotrophs may turn out to be cancerous and as these cells proliferate, they spike the level of prolactin in the body. In such cases, the carcinogenic growths may be got rid of by means of surgery. If a patient experiences such a condition, it will be essential for him/ her to take supplementary medicines to make certain that their body has a proper balance of various hormones.
Deficiency of prolactin in the body may cause a number of dysfunctions. For instance, prolactin hypersecretion may lead to disappearance of menstrual period. In addition, prolactin deficiency is also associated with a condition known as Sheehan's Syndrome, wherein the previous pituitary gland of a woman may be damaged following childbirth. On the other hand, excessive prolactin production in men may result in hormonal disorders; for instance, they may experience emergence of secondary female sexual characteristics like breasts. Some men may also suffer from erectile dysfunction due to excessive prolactin production in their body.
The production of prolactin can be regulated by ingestion of specific foods that have high concentration of antioxidants. Apart from berries and green leafy vegetables, any food with high antioxidant content may help in regulating prolactin production. Foods containing zinc are excellent for prolactin production. Such foods include red meats, seafood, sunflower seeds and soy sauce can be helpful.
Understanding the place and manner in which prolactin is produced is something that is really complex. Basically, the pituitary gland produces this hormone. In addition, several body tissues like the adipose tissue, breasts, brain, prostate, immune system cells, uterus and the skin also makes prolactin. Prolactin has a tendency to work locally. This hormone is released locally in the areas where it has specific functions.
Since the neurotransmitter dopamine holds back prolactin secretion, there is a negative feedback loop of production of this hormone. When prolactin release is restrained by dopamine, it results in augments secretion of dopamine. While estrogen and thyrotropin-releasing hormone helps to fuel production of prolactin, no major prolactin-releasing hormone exists in the body. Estrogen helps to promote release of prolactin, especially when the estrogen level in the body is at its maximum - the time when a woman has a menstrual cycle.
It has been found that non-lactating women usually have very low levels of prolactin. Same is the case with men and women who are not expecting. The production of this hormone starts picking up during REM (rapid eye movement) sleep and it is at its highest during the early part of the morning.
Suckling primarily promotes secretion of prolactin in females. This mechanism is attributed to the activity of neurons, which transmit message to push milk to the breasts. When a baby suckles or breastfeeds, it triggers mechanoreceptors surrounding the nipple and the nerve fibers transmit the message to the hypothalamus to start production of prolactin. As a result, a change occurs in the electrical activity of neurons eventually resulting in enhanced secretion of prolactin. The sulking action of the baby simultaneously activates the pituitary gland to secrete oxytocin, which, in turn, kicks off milk let-down. It is worth mentioning here that prolactin is responsible for stimulating production of milk, while the oxytocin hormone works to fill the breasts with milk for the baby to feed on.
Aside from suckling, there are a number of chemicals that can also affect the secretion of prolactin. These chemicals include peptide histidine, vasoactive intestinal peptide, anti-diuretic hormone, progesterone and isoleucine.
Other than the chemicals that stimulate prolactin secretion, production and release of prolactin can also be augmented by taking protein-rich meals, physical and/or emotional stress, exercise, minor surgical procedures and even epileptic seizures.
Prolactin has two primary functions and these include stimulating milk production and developing the tissues in the breast. Prolactin is essential in development of breasts along with progesterone and estrogen. Together, they augment further breast growth as well as making the alveoli larger to prepare them for lactation. Apart from developing the breast tissues, prolactin plays a vital part in production of milk.
Prolactin fuels of production of milk by stimulating an enzyme that amalgamates the elements that make up milk - for instance casein (the protein contained in milk), lactose (the carbohydrate content of milk) and lipids. Prolactin plays a major role in biosynthesizing the constituents of milk by attaching itself to the cell membrane and stimulating the transcription cascade enabling the production of enzymes necessary for production of milk. During this process lactogenesis does not take place till parturition is over because elevated levels of progesterone and estrogen levels in a woman during pregnancy suppresses the prolactin receptors present in the breasts. Following parturition, there is a sharp and sudden decrease in the levels of estrogen and progesterone. As a result, the stimulatory consequences on the breasts disappear. The level of prolactin remains high till the time a baby continues to breastfeed following pregnancy and every time the baby suckles, the production of prolactin remains at its highest level. However, if a mother does not breastfeed her baby, the levels of prolactin drop to the levels during non-pregnant stage after a couple of weeks.