Thyrotropin-releasing hormone

protein
Name = thyrotropin-releasing hormone
caption = Structural formula of TRH



width = 200
HGNCid = 12298
Symbol = TRH
AltSymbols =
EntrezGene = 7200
OMIM = 275120
RefSeq = NM_007117
UniProt = P20396
PDB =
ECnumber =
Chromosome = 3
Arm = q
Band = 13.3
LocusSupplementaryData = -q21

Thyrotropin-releasing hormone (TRH), also called thyrotropin-releasing factor (TRF), thyroliberin or protirelin, is a tropic tripeptide hormone that stimulates the release of thyroid-stimulating hormone and prolactin by the anterior pituitary.

Production

TRH is produced by the hypothalamus in medial neurons of the paraventricular nucleus. [cite journal |author=Taylor T, Wondisford F, Blaine T, Weintraub B |title=The paraventricular nucleus of the hypothalamus has a major role in thyroid hormone feedback regulation of thyrotropin synthesis and secretion |journal=Endocrinology |volume=126 |issue=1 |pages=317–24 |year=1990 |pmid=2104587] Initially, it is synthesized as a 242 amino acid precursor polypeptide that contains 6 copies of the sequence -Glu-His-Pro-Gly-, flanked by di-basic peptides that are later processed through proteolysis to give the mature TRH molecule.

It travels across the median eminence to the anterior pituitary gland via the hypophyseal portal system where it stimulates the release of thyroid stimulating hormone from cells called thyrotropes. [ [http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/tsh.html Thyroid-Stimulating Hormone ] ]

In addition to the brain, TRH can also be detected in other areas of the body including the gastrointestinal system and pancreatic islets.

History

The sequence of TRH was first determined and the hormone synthesized by Roger Guillemin and Andrew V. Schally in 1969. [Boler J, Enzmann F, Folkers K, Bowers CY, Schally AV. "The identity of chemical and hormonal properties of the thyrotropin releasing hormone and pyroglutamyl-histidyl-proline amide." Biochem Biophys Res Commun 1969;37:705-10. PMID 4982117] [Burgus R, Dunn TF, Desiderio D, Guillemin R. "Molecular structure of the hypothalamic hypophysiotropic TRF factor of ovine origin: mass spectrometry demonstration of the PCA-His-Pro-NH2 sequence." Comptes Rendus hebdomadaires des Séances de l’Académie des Sciences 1969;269:1870–1873. ]

Chemical properties

Its molecular weight is 359.5 Da.

Its structure is:(pyro)Glu-His-Pro-NH2

Clinical significance

It is used in pharmacology (brand name Relefact TRH) to test the response of the anterior pituitary gland.

Medical preparations of TRH are used in diagnostic tests of thyroid disorders and in acromegaly.

A TRH test may be indicated if secondary hypothyroidism is suspected. Some patients may have low levels of circulating thyroid hormones and secondary hypothyroidism as a result of damage to the hypothalamic or pituitary control mechanisms that regulate thyroid function. The hypothalamus makes a small hormone called TRH that directs the synthesis and secretion of TSH from the pituitary gland. If these normal regulatory mechanisms are interrupted, the pituitary may not be able to produce appropriate levels of TSH and levels of thyroid hormones may decline, although the TSH remains appropriately normal. The TRH test involves administration of a small amount of TRH intravenously, following which levels of TSH will be measured at several subsequent time points using samples of blood taken from a peripheral vein. Patients with normal function of the hypothalamic-pituitary axis (HPA) respond by increasing the levels of TSH following TRH injection. Patients with compromised HPA function may exhibit a delayed, blunted, or absent response to TRH administration. TRH may cause nausea, vomiting and some patients experience an urge to urinate. Rarely, TRH may cause blood vessel constriction leading to hemorrhage in patients with pre-existing pituitary tumors. Accordingly, patients should be advised about the risks, albeit rare, of TRH testing. [http://www.mythyroid.com/TRHtest]

ee also

* Thyrotropin-releasing hormone receptor

References


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Look at other dictionaries:

  • thyrotropin-releasing hormone — n a tripeptide hormone synthesized in the hypothalamus that stimulates secretion of thyroid stimulating hormone by the anterior lobe of the pituitary gland abbr. TRH called also protirelin, thyrotropin releasing factor * * * (TRH) a tripeptide… …   Medical dictionary

  • thyrotropin-releasing hormone — [thī΄rə trō′pinri lēs′iŋ] n. a hormone produced by the hypothalamus that stimulates the production of thyrotropin: sometimes called thyrotropin releasing factor …   English World dictionary

  • thyrotropin-releasing hormone — noun hormone released by the hypothalamus that controls the release of thyroid stimulating hormone from the anterior pituitary • Syn: ↑TRH, ↑thyrotropin releasing factor, ↑TRF, ↑protirelin • Hypernyms: ↑hormone, ↑endocrine, ↑i …   Useful english dictionary

  • thyrotropin-releasing hormone — /thuy reuh troh pin ri lee sing, thuy ro treuh /, Biochem. a small peptide hormone, produced by the hypothalamus, that controls the release of thyrotropin by the pituitary. Also called thyrotropin releasing factor. Abbr.: TRH [1965 70] * * * …   Universalium

  • thyrotropin-releasing hormone — noun Date: 1968 a tripeptide hormone synthesized in the hypothalamus that stimulates secretion of thyroid stimulating hormone called also thyrotropin releasing factor …   New Collegiate Dictionary

  • thyrotropin-releasing hormone — thyrotro′pin releas ing hor mone n. biochem. See TRH • Etymology: 1965–70 …   From formal English to slang

  • thyrotropin-releasing hormone test — thyrotropin releasing hormone stimulation test (for thyroid function) pituitary release of thyrotropin is assessed by administration of a bolus of thyrotropin releasing hormone and measurement of serum concentrations of thyrotropin at intervals.… …   Medical dictionary

  • Thyrotropin-releasing hormone receptor — The thyrotropin releasing hormone receptor (TRHR) is a G protein coupled receptor which binds the tripeptide thyrotropin releasing hormone.cite journal | author = Yamada M, Monden T, Konaka S, Mori M | title = Assignment of human thyrotropin… …   Wikipedia

  • thyrotropin-releasing factor — noun hormone released by the hypothalamus that controls the release of thyroid stimulating hormone from the anterior pituitary • Syn: ↑thyrotropin releasing hormone, ↑TRH, ↑TRF, ↑protirelin • Hypernyms: ↑hormone, ↑endocrine, ↑ …   Useful english dictionary

  • Releasing hormone — A releasing hormone or releasing factor is a hormone whose main purpose is to control the release of another hormone. The main releasing hormones secreted by the hypothalamus are:*Thyrotropin releasing hormone (TRH), *Corticotropin releasing… …   Wikipedia

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