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Pituitary prolactin secretion is regulated by endocrine neurons in the hypothalamus. The most important of these are the neurosecretory tuberoinfundibulum (TIDA) neurons of the arcuate nucleus that secrete dopamine (a.k.a. Prolactin Inhibitory Hormone) to act on the D 2 receptors of lactotrophs, causing inhibition of prolactin secretion.
Dopamine released by many groups of neurons in the brain inhibits the secretion of prolactin by activating D2 Dopamine receptors on lactotrophs in the pituitary gland. [31] Prolactin directly stimulates hypothalamic dopamine neurons, which in turn inhibit the secretion of prolactin, creating a succinct negative feedback mechanism for regulation.
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 agonists, cabergoline and bromocriptine bind to specific dopamine receptors to block the secretion pathway of prolactin and shrink the size of tumor (prolactinoma), which subsequently treat infertility caused by elevated level of prolactin. [46] (See also : Hyperprolactinaemia) Chemical structure of Bromocriptine
The arcuate nucleus and the periventricular nucleus of the hypothalamus have dopamine neurons that form an important projection—the tuberoinfundibular pathway which goes to the pituitary gland, where it influences the secretion of the hormone prolactin. [50] Dopamine is the primary neuroendocrine inhibitor of the secretion of prolactin from ...
Prolactin inhibitors are mainly used to treat hyperprolactinemia (high prolactin levels). [1] Agonists of the dopamine D 2 receptor such as bromocriptine and cabergoline are able to strongly suppress pituitary prolactin secretion and thereby decrease circulating prolactin levels, and so are most commonly used as prolactin inhibitors. [1]
Dopamine released from their nerve endings at the median eminence is transported to the anterior pituitary gland, where it regulates the secretion of prolactin. Dopamine inhibits prolactin secretion, so when the TIDA neurons are inhibited, there is increased secretion of prolactin, which stimulates lactogenesis (milk production).