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Prolactin hormone, formed by the pituitary gland, is the most vital hormone in our body. Prolactin controls reproductive health and is produced and secreted in the front portion of the pituitary gland (present in the brain). This hormone is found in both genders and is also secreted by immune cells, skin, adipose tissue, breasts, and the uterus. Prolactin is released by the respective glands causing the production of milk.
Key terms: Prolactin hormone, Hyperprolactinemia, Hyperprolactinemia, Pituitary Gland, Hormone, Reproductive health.
What is Prolactin hormone?
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Prolactin is the most important hormone, which is responsible for controlling reproductive health. Prolactin hormone affects the growth of women’s breasts and instructs them to produce milk during the time of pregnancy and after the birth of a child. Thus, it plays a fundamental role in stimulating the mammary alveoli, which are responsible for producing milk after the birth of a baby.
The prolactin hormone is mainly used in differentiating the cells that perform their own specific functions. This is a specific hormone, which is mainly produced when the body is exposed to high levels of the cortisol hormone for a longer period. Normally, the level of prolactin in new and pregnant mothers is high, and, on the other hand, prolactin level is low for non-pregnant. The blood test to detect the prolactin level in blood is known as the prolactin test and is usually carried out in pregnant women.
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Prolactin or PRL test
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PRL or prolactin test is the pathology test, mainly used to determine the level of prolactin hormone in an individual. This test is also used for diagnosing the following:
- Pituitary adenoma.
- Hypothalamic disease.
- Hyperprolactinemia disease.
- Monitor the prolactin-producing tumours.
- Causes of infertility in both males and females.
Structure of Prolactin
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The prolactin molecule is organized in a single chain of amino acids with 3 (three) intramolecular disulfide bonds between 6 (six) cysteine residues (Cys4-Cys11, Cys58-Cys174, and Cys191-Cys199 in humans). The human prolactin cDNA is 914 nucleotides in length and contains a 681-nucleotide open reading frame encoding the prolactin prohormone of 227 amino acids. The single peptide contains 28 amino acids; thus the mature human prolactin is composed of 199 amino acids. The secondary structure of prolactin contains 50% of the amino acid chain is arranged in α-helices, while the rest of it forms loops.
The tertiary structure of prolactin was anticipated by homology modeling approach, based on the structural similarities between prolactin and other helix bundle proteins, especially growth hormone. According to the current three-dimensional model, prolactin contains 4 (four) long α-helices arranged in antiparallel fashion. Although the main form of prolactin hormone found in the pituitary gland is 23 kDa. The variants of prolactin have been characterized in various mammals, including humans. Prolactin variants can be the results of different splicing of the primary transcript, proteolytic cleavage and other posttranslational modifications of the amino acid chain.
How is Prolactin Controlled?
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The prolactin level in both males and females remains the same till they attain puberty, but it rises or increases 2 to 3 times during deep sleep and there is a peak in the early morning hours.
| Age | Hormonal level in ng/mL |
|---|---|
| New Born baby | 30 to 495 ng/mL |
| Children | 3.2 to 20 ng/mL |
| Adult male | 0 to 20 ng/mL |
| Adult female | 0 to 25 ng/mL |
| Pregnant female | 20 to 400 ng/mL |
- Hyperprolactinaemia
- Hypoprolactinaemia
Difference between Hyperprolactinemia and Hyperprolactinemia
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The Differences between Hyperprolactinmeia and Hyperprolactinemia are| Hyperprolactinemia | Hypoprolactinemia |
|---|---|
| The condition of having more prolactin circulating in the blood is called hyperprolactinemia. | The condition of having less prolactin circulating in the blood is called hyperprolactinemia. It is not very common and may occur in people with the insufficient activity of the pituitary gland and Sheehan’s syndrome. |
| The causes of hyperprolactinemia include Pregnancy, Medications, Hypothalamus, Hypothyroidism, and Benign pituitary tumors. | Reduced secretion of prolactin hormones leads to inadequate milk being produced after giving birth. But, there are no particular indications related to a less level of prolactin, the preliminary evidence suggests that it might cause a reduced immune response to some infections. |
| Symptoms of hyperprolactinemia are Infertility, Anovulation, Amenorrhea, Abnormal hair growth, Unwanted production of milk, and Disturbances to the menstrual cycle. | The condition of having fewer prolactin hormones in males results in oligospermia and visual disturbance. |
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Things To Remember
- A prolactin test determines the prolactin hormone level in our blood.
- A person may need a prolactin test when facing the following symptoms.
- Milk production by a female who is neither pregnant nor breastfeeding.
- Fatigue, headache, change in the vision of a person.
- Abnormal periods or infertility in females.
- Enlarged breasts.
- Prolactin affects women’s normal menstrual cycle and may cause infertility in them. Prolactin release can also affect the release of gonadotropin-releasing hormone from the hypothalamus.
- If a woman does not feed breastmilk to her baby after delivery, her prolactin level falls in a few weeks.
- Pathologies related to prolactin are either associated with its deficiency or excess.
- Oestrogen is known as one of the main regulators of prolactin secretion during pregnancy. Prolactin can also facilitate the effects on the endocrine system.
Previous Year Questions
- Gastric secretion is stopped by hormone…? [NEET 1993]
- Feeling the tremors of an earthquake, a scared resident of seventh floor of a multistoryed building… [NEET 2007]
- Cholecystokinin and duocrinin are secreted by… [NEET 1999]
- Adrenaline directly affects on… [NEET 2002]
- ADH or vasopressin is… [ NEET 1991]
- Acromegaly is caused by… [NEET 2002]
- Which one of the following pair of organs include only endocrine glands ?... [NEET 2008]
- A steroid hormone which regulates glucose metabolism is… [NEET 2006]
- Which one of the following pairs correctly matches a hormone with a disease resulting from its deficiency… [NEET 2004]
- Chemically hormones are… [NEET 2004]
- A health disorder that results from the deficiency of thyroxine in adults and characterised by… [NEET 2009]
- A pregnant female delivers a baby who suffers from stunted growth, mental retardation… [NEET 2013]
Sample Question
Ques. What is the meaning of prolactin, and mention the name of body parts that can release prolactin? (2 marks)
Ans. Prolactin is a hormone formed by the pituitary gland of the human body. Prolactin can be produced in different parts of the body like the uterus, immune cells, breasts, brain, skin, etc.
Ques. What is responsible for high prolactin levels in the human body? (2 marks)
Ans. Mostly, the tumour present in the pituitary gland is responsible for the growth prolactin levels in the human body because the tumour guides the pituitary to release high amounts of prolactin.
Ques. What effect does the high or low level of prolactin cause? (2 marks)
Ans. High prolactin causes milk production both in genders, who are not pregnant.
Low prolactin levels can affect breast milk production after giving birth as it causes low or insufficient breast milk production and can cause some infections.
Ques. What Are The Symptoms Of Low Prolactin? (4 marks)
Ans. Symptoms of low prolactin levels include:
- Infertility
- Absence of periods / irregular periods
- Breast Milk discharge when not pregnant or nursing
- Vision problems
- Headaches
Ques. Name two regulators of prolactin in the body. (2 marks)
Ans. Two regulators of prolactin in the body are:
Dopamine decreases the production of prolactin in the body. When the amount of dopamine increases in the bloodstream, then the amount of prolactin decreases.
Oestrogen increases the production of prolactin in the body.
Ques. What is hyperprolactinaemia? (2 marks)
Ans. The condition of having more prolactin circulating in the blood is called hyperprolactinaemia. The causes of hyperprolactinaemia include Pregnancy, Medications, Hypothalamus, Hypothyroidism and Benign pituitary tumours
Ques. What is hyperprolactinaemia? (2 marks)
Ans. The condition of having less prolactin circulating in the blood is called hyperprolactinaemia. It is not very common and may occur in people with the insufficient activity of the pituitary gland and Sheehan’s syndrome.
Ques. What can cause prolactin levels to rise? Can stress cause high prolactin levels? (4 marks)
Ans. Any medication that affects the production of dopamine in your body can make your prolactin levels rise. Medications that can increase prolactin levels in your blood are High blood pressure medications, such as calcium channel blockers and methyldopa.
Prolactin levels also get higher during times of physical or emotional stress. Many prescriptions can cause prolactin levels to go up. Tumors of the pituitary gland can sometimes cause prolactin to be made. A damaged pituitary gland may not be able to make normal amounts of prolactin so levels will be lower.
Ques. Mention the uses of prolactin in our body. (5 marks)
Ans. Uses of prolactin are:
- Prolactin is mainly used to initiate and maintain lactation or milk production in milk-producing organisms(mammals).
- Prolactin helps in the induction of the lobular alveolar system and ductal growth.
- Prolactin also helps in the production of some proteins like casein and lactalbumin.
- Prolactin plays a crucial role in the regulation of fluids or osmoregulation.
- Prolactin is also used for metabolic processes, such as for the metabolism of fats, carbohydrates, calcium and Vitamin D.
- Prolactin is also used for foetal lung development.
- Prolactin takes part in the formation of steroids from the adrenal cortex and ovaries.
Ques. What is the difference between the prolactin hormone and the oxytocin hormone? (3 marks)
Ans. The Difference the prolactin hormone and the oxytocin hormone are-
| Prolactin hormone | Oxytocin hormone |
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