Prolactin


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Related to Prolactin: oxytocin, progesterone, TSH

prolactin

[prō ′lak·tən]
(biochemistry)
A protein hormone produced by the adenohypophysis; stimulates lactation and promotes functional activity of the corpus luteum. Also known as lactogenic hormone; luteotropic hormone; mammary-stimulating hormone; mammogen; mammogenic hormone; mammotropin.

Prolactin

 

(also, lactogenic hormone), in mammals, a hormone that controls lactation.

Prolactin is a protein with a molecular weight of 23–24 × 103. In 1969, C. Lee and his colleagues (USA) established the primary structure of prolactin in sheep; 198 radicals of 18 amino acids form a polypeptide chain with three internal disulfide (—S—S—) bonds, which must be preserved for hormonal activity. Prolactin is synthesized in special acidophilic cells of the anterior lobe of the pituitary gland; its formation is controlled by a special substance that is produced in the hypothalamus. In women, the concentration of prolactin in the blood increases during pregnancy from 5–10 to 200 nanograms per milliliter; sucking during breast-feeding further stimulates the secretion of prolactin.

The mechanism of action of prolactin consists in binding with a specific receptor in the plasma membrane of the secretory alveolar cell, which results in the activation of the enzyme protein kinase and the biosynthesis of various types of ribonucleic acids (RNA); subsequently, the synthesis of milk proteins and their secretion into the ducts of the mammary gland is induced. Prolactin has also been found in males, although its functions are not clear.

In mammals, prolactin also promotes the formation of the maternal instinct; in some mammals, for example, rats and mice, prolactin promotes the functioning of the ovarian corpus luteum, which is the derivation of the term “luteotropic hormone,” the earlier name for prolactin.

In lower vertebrates, such as fish and amphibians, the functions of hormones analogous to prolactin are extremely varied; they control, for example, osmoregulation, water metabolism, skin pigmentation, and migration during the reproductive period.

REFERENCES

Sovremennye voprosy endokrinologii, issue 4. Moscow, 1972. Pages 30–34.
Lactogenic Hormones. Edited by G. E. Wolstenholme and J. Knight. Edinburgh-London, 1972.
Cowie, A. T. The Physiology of Lactation. London, 1971.

B. V. POKROVSKII

References in periodicals archive ?
The aim of this study was to explore the correlation between maternal prolactin in the third trimester of pregnancy and cord blood prolactin, the correlation between cord blood prolactin and birth weight of the neonates, and to compare cord blood prolactin level in newborns of women with normal pregnancy and women with pregnancy complications namely; gestational hypertension, gestational diabetes and preterm labour.
A review of the effects of antipsychotic medication on prolactin levels showed that the incidence of hyperprolactinemia was 90% with haloperidol, 80% with pimozide, 62% with risperidone, 31% with olanzapine while clozapine, quetiapine and ziprasidone were prolactinsparing7.
"Our epidemiological observations, coupled with previous population data and emerging experimental evidence, support a potential protective role of prolactin (within the biologically normal range) in the pathogenesis of type 2 diabetes risk in women," the authors write.
It is critical to determine if a temporal relationship exists between exposure to an antipsychotic and increase in prolactin levels.
Mean prolactin level was significantly elevated (p = 0.0017) in females with hormonal imbalance (Table 2).
Patients having high levels of prolactin, lactating mothers, pregnant women, and patients on antidepressant or estrogen therapy were excluded from the study.
Radioimmunoassay for Prolactin. The concentration of prolactin in medium was assayed by the RIA double-antibody method using specific anti-ovine-PRL and anti-rabbit-[gamma]-globulin antisera as previously described [22].
indicate that reporting of the incidence of adverse events in pediatric schizophrenia patients is limited and prolactin elevation as an adverse event is reported more often in the pediatric schizophrenia population who are on antipsychotics.
Along with GH and IL-6 receptors, prolactin receptors are a member of the type I cytokine receptor family.
His imaging revealed a giant pituitary tumour (59 x 45 x 42 mm) with extrasellar extension (Figure 1(a)) with initial prolactin of 91,800 [micro]g/L confirming the diagnosis of giant prolactinoma.