Prolactin (PRL) also known as is a protein that in humans is encoded by the PRL gene.

Prolactin is a peptide hormone discovered by Oscar Riddle and important later work was done by Henry Friesen. Although it is perhaps best known for its role in lactation, prolactin already existed in the oldest known vertebrates—fish—where its most important functions were probably related to control of water and salt balance.

Prolactin also acts in a cytokine-like manner and as an important regulator of the immune system. Prolactin has important cell cycle related functions as a growth-, differentiating- and anti-apoptotic factor. As a growth factor binding to cytokine like receptors it has also profound influence on hematopoiesis, angiogenesis and is involved in the regulation of blood clotting through several pathways. In summary, "more than 300 separate actions of PRL have been reported in various vertebrates, including effects on water and salt balance, growth and development, endocrinology and metabolism, brain and behavior, reproduction, and immune regulation and protection". Prolactin acts in endocrine, autocrine, and paracrine manner through the prolactin receptor and a large number of cytokine receptors.

Pituitary prolactin secretion is regulated by endocrine neurons in the hypothalamus, the most important ones being the neurosecretory tuberoinfundibulum (TIDA) neurons of the arcuate nucleus, which secrete dopamine to act on the D2 receptors of lactotrophs, causing inhibition of prolactin secretion. Thyrotropin-releasing factor (thyrotropin-releasing hormone) has a stimulatory effect on prolactin release.

Vasoactive intestinal peptide and peptide histidine isoleucine help to regulate prolactin secretion in humans, but the functions of these hormones in birds can be quite different.

Prolactin is sometimes classified as a gonadotropin although in humans it has only a weak luteotropic effect while the effect of suppressing classical gonadotropic hormones is more important.

Several variants and forms are known per species. Many fishes have variants prolactin A and prolactin B. Most vertebrates including humans also have the closely related somatolactin. In humans 3 smaller (4, 16, and 22 kDa) and several larger (so called big and big-big) variants exist.

Read more about ProlactinEffects, Production and Regulation, Variance in Levels, Structure and Variations, Prolactin Receptor, Diagnostic Use, Units and Unit Conversions, Reference Ranges, Conditions Associated With Elevated Prolactin Secretion, Conditions Associated With Decreased Prolactin

Other articles related to "prolactin":

Prolactin-releasing Peptide
... Prolactin-releasing peptide (PrRP) is a peptide hormone that in humans is encoded by the PRLH gene ... PrRP stimulates prolactin (PRL) release and regulates the expression of prolactin through binding to the prolactin-releasing peptide receptor (GPR10) ...
Conditions Associated With Decreased Prolactin
... Hypoprolactinaemia, or serum prolactin deficiency, is associated with ovarian dysfunction in women, and metabolic syndrome, anxiety, arteriogenic erectile dysfunction ... In one study, normal sperm characteristics were restored when prolactin levels were brought up to normal values in hypoprolactinemic men ...
Prolactin-releasing Hormone
... Prolactin-releasing hormone, also known as PRLH, is a hypothetical human hormone or hormone releasing factor ... Existence of this factor has been hypothesized as prolactin is the only currently known hormone for which almost exclusively negative regulating factors are known (such ... While many prolactin stimulating and enhancing factors are well known (such as thyrotropin-releasing hormone, oxytocin, and estrogen) those have primary functions other ...
Tomingal-like Peptide
... to the following symptoms microcephaly microgenitalia gynecomastia excessive prolactin release and regression of the mullerian duct during development ... confirmed to be found on chromosome 6, near the prolactin gene location, with a similar promoter ... Excessive prolactin leads to gynecomastia, as well as microgenitalia ...
Tiapride - Side Effects
... This is likely related to its side effects on levels of the hormone prolactin, which is involved in sexual development ... Tiapride has been found to cause excess prolactin levels in plasma, which can cause decreased libido, infertility and increased risk of breast cancer ... This is because dopamine plays a primary role in regulating prolactin release by binding to D2 receptors on prolactin-secreting cells in the anterior pituitary ...