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Encyclopedia > Prolactin
Prolactin
Identifiers
Symbol PRL
Entrez 5617
HUGO 9445
OMIM 176760
RefSeq NM_000948
UniProt P01236
Other data
Locus Chr. 6 p22.2-p21.3

Prolactin (PRL) is a peptide hormone primarily associated with lactation. In breastfeeding, the infant suckling the teat stimulates the production of prolactin, which fills the breast with milk (lactogenesis) in preparation for the next feed. Oxytocin, a similar hormone, is also released, which triggers milk let-down. Image File history File links PRL_structure. ... The Entrez logo The Entrez Global Query Cross-Database Search System allows access to databases at the National Center for Biotechnology Information (NCBI) website. ... Look up Hugo in Wiktionary, the free dictionary. ... The Mendelian Inheritance in Man project is a database that catalogues all the known diseases with a genetic component, and - when possible - links them to the relevant genes in the human genome. ... National Center for Biotechnology Information logo The National Center for Biotechnology Information (NCBI) is part of the United States National Library of Medicine (NLM), a branch of the National Institutes of Health. ... Swiss-Prot is a curated biological database of protein sequences created in 1986 by Amos Bairoch during his PhD and developed by the Swiss Institute of Bioinformatics and the European Bioinformatics Institute. ... Short and long arms Chromosome. ... Chromosome 6 is one of the 23 pairs of chromosomes in humans. ... Peptide hormones are a class of peptides that are secreted into the blood stream and have endocrine functions in living animals. ... Kittens nursing Lactation describes the secretion of milk from the mammary glands, the process of providing that milk to the young, and the period of time that a mother lactates to feed her young. ... A human infant In basic English usage, an infant is defined as a human child at the youngest stage of life, especially before they can walk or simply a child before the age of one[1] (see also child and adolescent). ... A goat kid feeding on its mothers milk Teat is an alternative word for the nipple of a mammary gland, in humans referred to as a breast, from which milk is discharged. ... A pregnant womans breasts. ... A glass of cows milk. ... Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. ... Oxytocin (Greek: quick birth) is a mammalian hormone that also acts as a neurotransmitter in the brain. ...

Contents

Production and regulation

It is synthesised and secreted by lactotrope cells in the adenohypophysis (anterior pituitary gland). It is also produced in other tissues including the breast and the decidua. Lactotropes are cells in the anterior pituitary which produce prolactin. ... The anterior pituitary (also called the adenohypophysis) comprises the anterior lobe of the pituitary gland and is part of the endocrine system. ... The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea that sits in a small, bony cavity (sella turcica) covered by a dural fold (sellar diaphragm) at the base of the brain. ... A pregnant womans breasts. ... Decidua is the term for the uterine lining (endometrium) during a pregnancy. ...


Pituitary prolactin secretion is regulated by neuroendocrine neurons in the hypothalamus, most importantly by neurosecretory dopamine neurons of the arcuate nucleus, which inhibit prolactin secretion. Thyrotropin-releasing factor has a stimulatory effect on prolactin release. This article needs to be cleaned up to conform to a higher standard of quality. ... The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). ... Dopamine is a phenethylamine naturally produced by the human body. ... The arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence. ... For other uses, see TRH (disambiguation). ...


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.[1] VIP is a peptide hormone containing 28 amino acid residues. ... Peptide PHI (or peptide histidine isoleucine) is a peptide which functions as a hormone. ...


Effects

"The major effect of increased prolactin is a decrease in normal levels of sex hormones — estrogen in women and testosterone in men." [1]


Prolactin has many effects:

  • The most important of which is to stimulate the mammary glands to produce milk (lactation). Increased serum concentrations of prolactin during pregnancy cause enlargement of the mammary glands of the breasts and increases the production of milk. However, the high levels of progesterone during pregnancy act directly on the breasts to stop ejection of milk. It is only when the levels of this hormone fall after childbirth that milk ejection is possible. Sometimes, newborn babies (males as well as females) secrete a milky substance from their nipples. This substance is commonly known as Witch's milk. This is caused by the fetus being affected by prolactin circulating in the mother just before birth, and usually stops soon after birth.
  • Other possible functions of prolactin include the surfactant synthesis of the fetal lungs at the end of the pregnancy and immune tolerance of the fetus by the maternal organism during pregnancy.

Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. ... Kittens nursing Lactation describes the secretion of milk from the mammary glands, the process of providing that milk to the young, and the period of time that a mother lactates to feed her young. ... A pregnant woman near the end of her term Pregnancy is the carrying of one or more offspring in an embryonal or fetal stage of development by female mammals, including humans, inside their bodies, between the stages of conception and birth. ... Mammary glands are the organs that, in the female mammal, produce milk for the sustenance of the young. ... Progesterone is a C-21 steroid hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. ... Typical human female nipple and areola. ... Witchs milk or neonatal milk is milk secreted from the breasts of some newborn infants. ... The University of Paisley operates across three campus sites in the west and south-west of Scotland: Paisley, Ayr and Dumfries. ... The ETH Zurich, often called Swiss Federal Institute of Technology, is a science and technology university in the city of Zurich, Switzerland. ... An orgasm (sexual climax) is the conclusion of the plateau phase of the sexual response cycle, and is experienced by both males and females. ... This article is about sexual practices (i. ... Norepinephrine A hormone (from Greek όρμή - to set in motion) is a chemical messenger from one cell (or group of cells) to another. ... Turn on redirects here. ... In sexual intercourse, the refractory period is a recovery phase after male ejaculation during which it is physiologically impossible for almost all men to experience sustained erection and additional ejaculations or orgasms. ... Erectile dysfunction (ED) or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis. ... For other uses, see Libido (disambiguation). ... Prolactin is a hormone secreted by lactotropes in the adenohypophysis (anterior pituitary gland) which is made up of 199 amino acids with a molecular weight of about 23,000 daltons. ... Oligodendrocyte precursor cells in nervous tissue cells precede oligodendrocytes, and may also be able to generate neurons and astrocytes. ... Oligodendrocytes (from Greek literally meaning few tree cells), or oligodendroglia (Greek, few tree glue),[1] are a variety of neuroglia. ... Myelin is an electrically insulating phospholipid layer that surrounds the axons of many neurons. ... An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... A diagram showing the CNS: 1. ... Surfactants are wetting agents that lower the surface tension of a liquid, allowing easier spreading, and lower the interfacial tension between two liquids. ... Human respiratory system The lungs flank the heart and great vessels in the chest cavity. ... Immune or immunological tolerance is the process by which the immune system does not attack an antigen. ...

Variance in levels

There is a diurnal as well as an ovulatory cycle in prolactin secretion. Look up day in Wiktionary, the free dictionary. ... Ovulation is the process in the menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum (also known as an oocyte, female gamete, or casually, an egg) that participates in reproduction. ...


During pregnancy, high circulating concentrations of estrogen promote prolactin production. The resulting high levels of prolactin secretion cause further maturation of the mammary glands, preparing them for lactation. A pregnant woman near the end of her term Pregnancy is the carrying of one or more offspring in an embryonal or fetal stage of development by female mammals, including humans, inside their bodies, between the stages of conception and birth. ... Estriol. ...


After childbirth, prolactin levels fall as the internal stimulus for them is removed. Sucking by the baby on the nipple then promotes further prolactin release, maintaining the ability to lactate. The sucking activates mechanoreceptors in and around the nipple. These signals are carried by nerve fibres through the spinal cord to the hypothalamus, where changes in the electrical activity of neurons that regulate the pituitary gland cause increased prolactin secretion. The suckling stimulus also triggers the release of oxytocin from the posterior pituitary gland, which triggers milk let-down: prolactin controls milk production (lactogenesis) but not the milk-ejection reflex; the rise in prolactin fills the breast with milk in preparation for the next feed. Parturition redirects here. ... The hypothalamus links the nervous system to the endocrine system via the pituitary gland (hypophysis). ... Oxytocin (Greek: quick birth) is a mammalian hormone that also acts as a neurotransmitter in the brain. ... The posterior pituitary (also called the neurohypophysis) comprises the posterior lobe of the pituitary gland and is part of the endocrine system. ...


Usually, in the absence of galactorrhea, lactation will cease within one or two weeks of the end of demand breastfeeding. Galactorrhea or galactorrhoea is the spontaneous flow of milk from the breast, unassociated with childbirth or nursing. ... Breastfeeding an infant Symbol for breastfeeding (Matt Daigle, Mothering magazine contest winner 2006) Breastfeeding is the feeding of an infant or young child with milk from a womans breasts. ...


High prolactin levels also tend to suppress the ovulatory cycle by inhibiting the secretion of both FSH and GnRH. Follicle stimulating hormone (FSH) is a hormone produced by gonadotropes in the anterior pituitary gland. ... Gonadotropin Releasing Hormone (GnRH) is a peptide hormone responsible for the release of FSH and LH from the anterior pituitary. ...


Structure

Prolactin is a single chain polypeptide of 199 amino acids with a molecular weight of about 24,000 daltons. Its structure is similar to that of growth hormone and placental lactogen. The molecule is folded due to the activity of three disulfide bonds. Significant heterogeneity of the molecule has been described, thus bioassays and immunoassays can give different results due to differing glycosylation, phosphorylation, sulfation, as well as degradation. The non-glycosylated form of prolactin is the dominant form of prolactin that is secreted by the pituitary gland. Peptides are the family of molecules formed from the linking, in a defined order, of various amino acids. ... Phenylalanine is one of the standard amino acids. ... The unified atomic mass unit (u), or dalton (Da), is a small unit of mass used to express atomic masses and molecular masses. ... Growth hormone (GH or somatotropin) is a 191-amino acid, single chain polypeptide hormone which is synthesised, stored and secreted by the somatotroph cells within the lateral wings of the anterior pituitary gland, which stimulates growth and cell reproduction in humans and other animals. ... Human placental lactogen (HPL), also called human chorionic somatomammotropin, is a polypeptide placental hormone. ... In chemistry, a disulfide bond is a single covalent bond derived from the coupling of thiol groups. ... Also known as a biological assay, a bioassay is a measurement of the effects of a substance on living organisms. ... An immunoassay is a biochemical test that measures the concentration of a substance in a biological liquid, typically serum or urine, using the reaction of an antibody or antibodies to its antigen. ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... A phosphorylated serine residue Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule or the introduction of a phosphate group into an organic molecule. ... Sulfation refers to the process whereby a lead-acid battery (such as a car battery) loses its ability to hold a charge after it is kept in a discharged state too long due to the crystallization of lead sulfate. ... The pituitary gland, or hypophysis, is an endocrine gland about the size of a pea that sits in a small, bony cavity (sella turcica) covered by a dural fold (sellar diaphragm) at the base of the brain. ...


Little prolactin is apparently the result of removal of some amino acids, while big prolactin can be the product of interaction of several prolactin molecules.


Pit-1 is a transcription factor that binds to the prolactin gene at several sites to allow for the production of prolactin in the pituitary gland. A key regulator of prolactin production are estrogens that enhances growth of prolactin producing cells and stimulates prolactin production directly as well as suppressing dopamine. In molecular biology, a transcription factor is a protein that binds DNA at a specific promoter or enhancer region or site, where it regulates transcription. ... Estriol. ... Dopamine is a phenethylamine naturally produced by the human body. ...


Prolactin receptor

See prolactin receptor

The prolactin receptor—encoded by a gene on Chromosome 5p13-14—interacts with the prolactin molecule as a transmembrane receptor. ...

Diagnostic use

Prolactin levels may be checked as part of a sex hormone workup, as elevated prolactin secretion can suppress the secretion of FSH and GnRH, leading to hypogonadism, and sometimes causing erectile dysfunction in men. Hypogonadism is a medical term for a defect of the reproductive system which results in lack of function of the gonads (ovaries or testes). ... Erectile dysfunction (ED) or impotence is a sexual dysfunction characterized by the inability to develop or maintain an erection of the penis. ...


Prolactin levels may be of some use in distinguishing epileptic seizures from psychogenic non-epileptic seizures. The serum prolactin level usually rises following an epileptic seizure.[4] This article is about epileptic seizures. ... // Introduction Psychogenic non-epileptic seizures are a manifestation or a form of conversion disorder. ...


Conditions causing elevated prolactin secretion

Hyperprolactinaemia is the term given to having too-high levels of prolactin in the blood. Prolactin is a hormone secreted by lactotropes in the adenohypophysis (anterior pituitary gland) which is made up of 199 amino acids with a molecular weight of about 23,000 daltons. ...

  • Prolactinoma;
  • Excess thyrotropin-releasing hormone (TRH), usually in primary hypothyroidism.
  • A side effect of many anti-psychotic medications

A prolactinoma is a benign tumor (adenoma) of the pituitary gland that produces a hormone called prolactin. ... Thyrotropin-releasing hormone (TRH), also called thyrotropin-releasing factor (TRF) or protirelin, is a tripeptide hormone that stimulates the release of thyroid-stimulating hormone and prolactin by the anterior pituitary. ... This article or section does not cite its references or sources. ... The term antipsychotic is applied to a group of drugs used to treat psychosis. ...

Conditions causing decreased prolactin

Bulimia nervosa, more commonly known as bulimia, is a psychological condition in which the subject engages in recurrent binge eating followed by intentionally doing one or more of the following in order to compensate for the intake of the food and prevent weight gain: vomiting inappropriate use of laxatives, enemas... Dopamine is a phenethylamine naturally produced by the human body. ...

Use of breastfeeding as contraceptive

The World Health Organization states that demand breastfeeding is more than 98% effective as a contraceptive in the first six months postpartum. This effect is said to be responsible for the natural spacing of children seen in countries where contraception is not widely available, and is thought to be an evolutionary means of ensuring adequate care is provided to each newborn. The 98% effectiveness only applies if three criteria are met: The World Health Organization (WHO) is a specialized agency of the United Nations (UN) that acts as a coordinating authority on international public health. ... Postnatal (Latin for after birth) is the period beginning immediately after the birth of a child and extending for about six weeks. ...

  1. The mother has had no menstrual periods at all (amenorrhea);
  2. The baby is exclusively breast-fed;
  3. It is six months or less since birth.

If one or more of these conditions are broken, lactational amenorrhea is no longer a reliable form of birth control. This contraceptive method is highly effective as long as the three conditions above are fulfilled. Further, the WHO suggests that a woman who is still amenorrheic has a less than 5% chance of getting pregnant in the first year of her baby's life, as long as she is still breastfeeding on demand. Amenorrhoea (BE) or amenorrhea (AmE) is the absence of a menstrual period in a woman of reproductive age. ...


See also

A breastfeeding infant Breastfeeding is the practice of a woman feeding an infant (or sometimes a toddler or a young child) with milk produced from her mammary glands, usually directly from the nipples. ... A breastfeeding infant Breastfeeding is the practice of a woman feeding an infant (or sometimes a toddler or a young child) with milk produced from her mammary glands, usually directly from the nipples. ... Baby food is any food that is made specifically for infants, roughly between the ages of six months to two years. ... This article or section does not adequately cite its references or sources. ... Hormone is also the NATO reporting name for the Soviet/Russian Kamov Ka-25 military helicopter. ...

References

  1. ^ Kulick R, Chaiseha Y, Kang S, Rozenboim I, El Halawani M (2005). "The relative importance of vasoactive intestinal peptide and peptide histidine isoleucine as physiological regulators of prolactin in the domestic turkey". Gen Comp Endocrinol 142 (3): 267-73. PMID 15935152. 
  2. ^ New Scientist article on prolactin function relating to sex
  3. ^ Gregg, C. et al. (2007). White Matter Plasticity and Enhanced Remyelination in the Maternal CNS. Journal of Neuroscience 27(8): 1812-1823.
  4. ^ Banerjee S, Paul P, Talib V (2004). "Serum prolactin in seizure disorders". Indian Pediatr 41 (8): 827-31. PMID 15347871. 

External links


  Results from FactBites:
 
Prolactin - Wikipedia, the free encyclopedia (1045 words)
Pituitary prolactin secretion is regulated by neuroendocrine neurons in the hypothalamus, most importantly by neurosecretory dopamine neurons of the arcuate nucleus, which inhibit prolactin secretion.
Prolactin has many effects, the most important of which is to stimulate the mammary glands to produce milk (lactation).
The prolactin receptor - encoded by a gene on Chromosome 5p13-14 - interacts with the prolactin molecule as a transmembrane receptor.
  More results at FactBites »

 
 

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