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
Prolactin (PRL), also known as lactotropin, 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. Prolactin is secreted from the pit ...
is the only currently known hormone for which almost exclusively negative regulating factors are known (such as
dopamine
Dopamine (DA, a contraction of 3,4-dihydroxyphenethylamine) is a neuromodulatory molecule that plays several important roles in cells. It is an organic compound, organic chemical of the catecholamine and phenethylamine families. Dopamine const ...
,
leukemia inhibitory factor, some
prostaglandin
The prostaglandins (PG) are a group of physiologically active lipid compounds called eicosanoids having diverse hormone-like effects in animals. Prostaglandins have been found in almost every tissue in humans and other animals. They are derive ...
s) but few stimulating factor. Its secretion is mediated by estrogen from placenta during pregnancy to elevate blood level of prolactin . While many prolactin stimulating and enhancing factors are well known (such as
thyrotropin-releasing hormone
Thyrotropin-releasing hormone (TRH) is a hypophysiotropic hormone produced by neurons in the hypothalamus that stimulates the release of thyroid-stimulating hormone (TSH) and prolactin from the anterior pituitary.
TRH has been used clinicall ...
,
oxytocin
Oxytocin (Oxt or OT) is a peptide hormone and neuropeptide normally produced in the hypothalamus and released by the posterior pituitary. It plays a role in social bonding, reproduction, childbirth, and the period after childbirth. Oxytocin ...
,
vasoactive intestinal peptide
Vasoactive intestinal peptide, also known as vasoactive intestinal polypeptide or VIP, is a peptide hormone that is vasoactive in the intestine. VIP is a peptide of 28 amino acid residues that belongs to a glucagon/secretin superfamily, the ligan ...
and
estrogen
Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal acti ...
) those have primary functions other than stimulating prolactin release and the search for hypothetical releasing factor or factors continues.
The
prolactin-releasing peptide
Prolactin-releasing peptide (PrRP) is a peptide hormone that in humans is encoded by the ''PRLH'' gene. PrRP stimulates prolactin (PRL) release and regulates the expression of prolactin through binding to the prolactin-releasing peptide receptor ( ...
identified in 1998 was a candidate for this function, however as of 2008 it appears its function is not yet completely elucidated.
See also
*
Hypothalamic–pituitary–prolactin axis
The hypothalamic–pituitary–prolactin axis (HPP axis), also known as the hypothalamic–pituitary–mammary axis or hypothalamic–pituitary–breast axis, is a hypothalamic–pituitary axis which includes the secretion of prolactin (PRL; lute ...
References
Human hormones
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