Prolactin (PRL) is a hormone produced in the lactotropic cells in the anterior pituitary gland. It is especially important during the period of pregnancy and during breastfeeding. Several diseases may be related to prolactin.
What is prolactin?
Schematic diagram showing the anatomy and structure of the endocrine (hormone) system. Click to enlarge. Prolactin, or lactotropic hormone, is a hormone that is produced in the anterior pituitary gland and serves a variety of purposes. It consists of 199 amino acids and is found in all mammals. Depending on the species, the number of amino acids may vary. Prolactin is inhibited by endogenous substances such as gamma-aminobutyric acid and somatostatin. A deficiency of estrogens also impairs prolactin production.
Production, formation, and manufacture
The production of prolactin is tightly regulated by the hypothalamus. It is produced in the pituitary gland and from there it is transmitted to the mammary gland and other areas. There it enables various physical changes and stimulates the production of breast milk. The exact formation of the hormone is a complex process. For example, the anterior pituitary gland produces six different hormones, which enable stressful situations, growth, and lastly, the production of breast milk. However, the production of prolactin does not take place directly in the pituitary gland. Rather, the two hormones vasopressin and oxytocin are secreted, which are responsible for the corresponding processes. Oxytocin is responsible for allowing the output of breast milk. It is formed from the precursor protein oxytocin-neurphysin by the separation of peptide bonds. Proprotein convertase 1 initiates this process. The amount of hormones produced is also precisely regulated by the organism. It increases with the onset of pregnancy, but can already be influenced by a strong desire to have children. Benign prolactinomas can also autonomously produce prolactin as a group of cells. Prolactinomas are cysts or otherwise altered tissue that mimic the production of hormones. This creates an imbalance and leads to overproduction.
Function, effect, and properties
Among other things, prolactin is responsible for stimulating the growth of the mammary gland during pregnancy. It also enables milk production during lactation and suppresses ovulation. It does this by inhibiting the release of the necessary sex hormones. Prolactin thus prevents pregnancy during breastfeeding, although this is not the only function of the hormone. In connection with the birth of the child, for example, the so-called brood care behavior is triggered. This is colloquially understood as the care of parents for their offspring. However, prolactin levels do not only rise in the mother for this purpose. The mother’s partner also normally has a higher prolactin level. So prolactin has not only physical effects. Psychologically, increased production also brings about some changes. Accordingly, a strong excess can lead to far-reaching complaints. If too little prolactin is produced during breastfeeding, this is likewise a risk factor.
Diseases, complaints and disorders
Prolactin can trigger various complaints if there is overproduction or underproduction. Thus, women experience a cessation of menstruation and sexual aversion. An uncontrolled flow of milk from the mammary gland can also be the result of overproduction. The reason for this is increased milk production due to an excess of prolactin. Men suffer from potency weaknesses, are also affected by sexual aversion and can suffer psychological problems. The reason for the overproduction is usually a tumor. This mimics the hormone tissue and produces prolactin as well as other hormones. If this happens, it is called an adenoma. The overproduction can be stopped by surgical removal of the tumor or treatment with drugs. Preparations such as Dostinex have proven to be particularly effective. These are dopamine agonists that can break down tumors and cysts. In the case of underproduction, a wide variety of disorders can also occur. The most common are metabolic disorders and a reduced need to care for the infant.The production of milk can also be restricted, although this can also have various other causes. In addition, those affected by a prolactin deficiency experience sexual aversion and suffer from hair loss. Children can also be affected by a lack of prolactin. However, they do not show any symptoms because production does not yet play a major role. Only breast growth can occur prematurely in some cases. Similarly, puberty is delayed, but this rarely leads to problems. Women in particular are affected by more serious complaints. These can suffer from fertility problems in the case of a prolactin deficiency. Prolactin deficiency is very rare and can be treated by supplying needed substances. If the deficiency is due to damage to the pituitary gland, surgery may be required. However, such surgery is risky.
