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Prolactin (PRL), also known as lactotropin and mammotropin, is a protein best known for its role in enabling mammals to produce milk. It is influential in over 300 separate processes in various vertebrates, including humans. [5] Prolactin is secreted from the pituitary gland in response to eating, mating, estrogen treatment, ovulation and ...
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.
Elevated prolactin blood levels are typically assessed in women with unexplained breast milk secretion (galactorrhea) or irregular menses or infertility, and in men with impaired sexual function and milk secretion. If high prolactin levels are present, all known conditions and medications which raises prolactin secretion must be assessed and ...
High levels of prolactin during pregnancy and breastfeeding also increase insulin resistance, increase growth factor levels (IGF-1) and modify lipid metabolism in preparation for breastfeeding. During lactation, prolactin is the main factor maintaining tight junctions of the ductal epithelium and regulating milk production through osmotic balance.
Hypoprolactinemia is associated with ovarian dysfunction in women, [3] [4] and, in men, metabolic syndrome, [5] anxiety symptoms, [5] arteriogenic erectile dysfunction, [6] premature ejaculation, [5] oligozoospermia (low concentration of sperm in semen), asthenospermia (reduced sperm motility), hypofunction of seminal vesicles, and hypoandrogenism. [7]
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 ...
In the absence of regular, episodic suckling, which keeps prolactin concentrations high, levels of prolactin will quickly drop, the menstrual cycle will resume and hence normal estrogen and progesterone levels will return, and lactation will cease (that is, until next parturition, or until induced lactation (i.e., with a galactogogue), occurs ...
Mechanical detection of suckling increases prolactin levels in the body to increase milk synthesis. Excess prolactin may inhibit the menstrual cycle directly, by a suppressive effect on the ovary, or indirectly, by decreasing the release of GnRH. [2] Suckling is a pivotal factor in maintaining lactational amenorrhea postpartum.