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Dopamine produced by neurons in the arcuate nucleus is secreted into the hypophyseal portal system of the median eminence, which supplies the pituitary gland. [50] The prolactin cells that produce prolactin, in the absence of dopamine, secrete prolactin continuously; dopamine inhibits this secretion. [50]
Prolactin has a wide variety of effects. It stimulates the mammary glands to produce milk (): increased serum concentrations of prolactin during pregnancy cause enlargement of the mammary glands and prepare for milk production, which normally starts when levels of progesterone fall by the end of pregnancy and a suckling stimulus is present.
Prolactin secretion in the pituitary lactrotroph cells is normally suppressed by the brain chemical dopamine, which binds to dopamine receptors. Drugs that block the effects of dopamine at the pituitary or deplete dopamine stores in the brain may cause the pituitary to secrete excess prolactin without an inhibitory effect.
A prolactin cell (also known as a lactotropic cell, epsilon acidophil, lactotrope, lactotroph, mammatroph, mammotroph) is a cell in the anterior pituitary which produces prolactin (a peptide hormone) in response to hormonal signals including dopamine (which is inhibitory), thyrotropin-releasing hormone and estrogen (especially during pregnancy), which are stimulatory.
Dopamine released at this site inhibits the secretion of prolactin from anterior pituitary gland lactotrophs by binding to dopamine receptor D2. Some antipsychotic drugs block dopamine in the tuberoinfundibular pathway, which can cause an increase in the amount of prolactin in the blood (hyperprolactinemia).
Prolactin acts in a short-loop negative feedback manner to decrease its levels by stimulating the release of dopamine. Dopaminergic neurons of the arcuate also inhibit the release of gonadotropin-releasing hormone , explaining in part why lactating (or otherwise hyperprolactinemic ) women experience oligomenorrhea or amenorrhea (infrequency or ...
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 as dopamine, leukemia inhibitory factor, some prostaglandins) but few stimulating factor.
Increased serum prolactin (PRL) [5] concentration in patients' brains from psychiatric medicine can also affect sexuality. [6] Psychiatric medicine is known to cause the brain to form more dopamine receptors for the dopamine blocking effect.