PRL Full Form

Prolactin, also known as lactotropin, is a protein that aids in the production of milk in mammals. It has an impact on about 300 different processes in vertebrates, including humans. The pituitary gland secretes prolactin in reaction to eating, mating, oestrogen treatment, ovulation, and lactation. Between these occasions, it is abundantly secreted in pulses. Prolactin is important for metabolism, immune system modulation, and pancreatic development. Prolactin is a peptide hormone that is encoded by the PRL gene and was discovered in non-human animals about 1930 by Oscar Riddle and verified in humans in 1970 by Henry Friesen. The PRL gene codes for prolactin, a peptide hormone.

Prolactin is linked to milk production in mammals and is suspected to be involved in the regulation of water and salt balance in fish. Prolactin has cytokine-like properties and is a key immune system regulator.

Functions of Prolactin:

Prolactin has several different effects. It stimulates the mammary glands to create milk (lactation): increasing serum prolactin levels throughout pregnancy cause mammary gland expansion and prepare for milk production, which typically begins when progesterone levels decline near the end of pregnancy and a suckling stimulus is present. Prolactin is a hormone that influences maternal behaviour.

Prolactin impacts lipid synthesis differently in mammary and adipose cells in rats and lambs, according to research. Bromocriptine-induced prolactin insufficiency boosted adipocyte lipogenesis and insulin responsiveness while lowering them in the mammary gland.

Regulation of Prolactin:

The anterior pituitary, decidua, myometrium, breast, lymphocytes, leukocytes and prostate all make prolactin in humans.

Pituitary prolactin is regulated by the transcription factor Pit-1 (Pituitary-specific positive transcription factor 1), which binds to the prolactin gene at many locations. Extrapituitary prolactin is controlled by a superdistal promoter and does not appear to be impacted by dopamine. In experimental circumstances, the thyrotropin-releasing hormone and the vasoactive intestinal peptide enhance prolactin release, but their physiological impact is unknown. Suckling is the primary trigger for prolactin release, and its action is neuronally mediated. Estrogens, which promote the development of prolactin-producing cells and directly boost prolactin production while reducing dopamine, are a significant regulator of prolactin production.

Structure and Isoforms of Prolactin: 

Prolactin has a structure that is comparable to growth hormone and placental lactogen. The activity of three disulfide links causes the molecule to fold. Because of the molecule’s significant heterogeneity, bioassays and immunoassays can produce diverse results due to differences in glycosylation, phosphorylation, sulfation, and degradation. The non-glycosylated type of prolactin released by the pituitary gland is the most common.

Prolactin is Characterized in Three Following Sizes:

• Little prolactin—the most common type. Its molecular mass is around 22 kDa. It is a 198-amino-acid single-chain polypeptide that appears to be the product of amino acid elimination.
• Prolactin with a large molecular weight of 48 kDa . It could be the result of multiple prolactin molecules interacting. It appears to have very little biological action, if any at all.
• Big big Prolactin is about 150 kDa in size. It appears to be biologically inactive.

Prolactin Role in Diagnostic:

Elevated prolactin secretion can suppress the secretion of follicular stimulating hormone and gonadotropin-releasing hormone, resulting in hypogonadism and possibly erectile dysfunction. Prolactin levels may help identify epileptic seizures from non-epileptic psychogenic seizures. Following an epileptic episode, the level of serum prolactin normally rises.

Prolactin Role in Medicine:

Prolactin is commercially available for usage in animals other than humans. It is used to help animals produce more milk. Prolactin has a biological half-life of 15–20 minutes in humans. Agonists of the D2 receptor, such as bromocriptine and cabergoline, lower prolactin levels, while antagonists, such as domperidone, metoclopramide, haloperidol, risperidone, and sulpiride, raise prolactin levels. Galactogogues, such as domperidone, metoclopramide, and sulpiride, are used to enhance prolactin secretion in the pituitary gland and promote breastfeeding in humans.

Conclusion:

Lactation, certain breast tissue development, and milk production are all regulated by prolactin. Prolactin levels in the blood that are higher than usual can produce symptoms like irregular periods, infertility, and erectile dysfunction.

The most important hormone that regulates reproductive health is prolactin. Both males and females generate and secrete this hormone, which is produced and secreted in the front region of the pituitary gland in the brain. Prolactin hormone is produced by immune cells, skin, adipose tissue, breasts, and the uterus, in addition to the pituitary gland.

When a newborn baby suckles the mother’s breast, prolactin is released by the corresponding glands, prompting milk production.