thyrotropin-releasing hormone: Definition from Answers.com

thyrotropin-releasing hormone

Structural formula of TRH
Identifiers
Symbol	TRH
Entrez	7200
HUGO	12298
OMIM	275120
RefSeq	NM_007117
UniProt	P20396
Other data
Locus	Chr. 3 q13.3-q21

For other uses, see TRH (disambiguation).

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.

1 Synthesis
2 History
3 Chemical properties
4 Clinical significance
5 See also
6 References

Synthesis

The system of the thyroid hormones T3 and T4.^[1]

TRH is produced by the hypothalamus in medial neurons of the paraventricular nucleus.^[2] 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.^[3]

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.^[4]^[5] Both parties insist their labs determined it first: Schally first suggested the possibility in 1966, but abandoned it after Guillemin proposed TRH was not actually a peptide. Guillemin's chemist began concurring with these results in 1969, as NIH threatened to cut off funding for the project, leading both parties to return to work on synthesis.^[6]

Half of the 1977 Nobel Prize in Medicine was awarded to Schally and Guillemin "for their discoveries concerning the peptide hormone production of the brain."^[7] News accounts of their work often focus on their "fierce competition" and use of tons of sheep and pig brains to locate the hormone.^[6]

Chemical properties

Its molecular weight is 359.5 Da.

Its tripeptide 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.

References

^ References used in image are found in image article in Commons:Commons:File:Thyroid_system.png#References.
^ Taylor T, Wondisford FE, Blaine T, Weintraub BD (January 1990). "The paraventricular nucleus of the hypothalamus has a major role in thyroid hormone feedback regulation of thyrotropin synthesis and secretion". Endocrinology 126 (1): 317–24. PMID 2104587.
^ Bowen R (1998-09-20). "Thyroid-Stimulating Hormone". Pathophysiology of the Endocrine System. Colorado State University. http://www.vivo.colostate.edu/hbooks/pathphys/endocrine/hypopit/tsh.html. Retrieved 2009-03-04.
^ Boler J, Enzmann F, Folkers K, Bowers CY, Schally AV (November 1969). "The identity of chemical and hormonal properties of the thyrotropin releasing hormone and pyroglutamyl-histidyl-proline amide". Biochem. Biophys. Res. Commun. 37 (4): 705–10. doi:10.1016/0006-291X(69)90868-7. PMID 4982117. http://linkinghub.elsevier.com/retrieve/pii/0006-291X(69)90868-7.
^ Burgus R, Dunn TF, Desiderio D, Guillemin R (November 1969). "[Molecular structure of the hypothalamic hypophysiotropic TRF factor of ovine origin: mass spectrometry demonstration of the PCA-His-Pro-NH2 sequence]" (in French). C.R. Hebd. Seances Acad. Sci., Ser. D, Sci. Nat. 269 (19): 1870–3. PMID 4983502.
^ ^a ^b Woolgar, Steve; Latour, Bruno (1979). "Chapter 3: The Case of TRF(H)". Laboratory life: the social construction of scientific facts. Thousand Oaks: Sage Publications. ISBN 0-8039-0993-4.
^ "The Nobel Prize in Physiology or Medicine 1977". NobelPrize.org. http://nobelprize.org/nobel_prizes/medicine/laureates/1977/index.html. Retrieved 2009-03-04.

Endocrine system: hormones (Peptide hormones · Steroid hormones)

Endocrine
glands

Hypothalamic-
pituitary

Hypothalamus	GnRH · TRH · Dopamine · CRH · GHRH/Somatostatin

Posterior pituitary	Vasopressin · Oxytocin

Anterior pituitary	α (FSH FSHB, LH LHB, TSH TSHB, CGA) · Prolactin · POMC (CLIP, ACTH, MSH, Endorphins, Lipotropin) · GH

Adrenal axis

Adrenal cortex: aldosterone · cortisol · DHEA
Adrenal medulla: epinephrine · norepinephrine

Thyroid axis

Thyroid: thyroid hormone (T₃ and T₄) · calcitonin
Parathyroid: PTH

Gonadal axis

Testis: testosterone · AMH · inhibin

Ovary: estradiol · progesterone · activin and inhibin · relaxin (pregnancy)

Placenta: hCG · HPL · estrogen · progesterone

Other end.
glands

Pancreas: glucagon · insulin · somatostatin

Pineal gland: melatonin

Thymus: Thymosin · Thymopoietin · Thymulin

Non-end.
glands

digestive system: Stomach: gastrin · ghrelin · Duodenum: CCK · GIP · secretin · motilin · VIP · Ileum: enteroglucagon · Liver/other: Insulin-like growth factor (IGF-1, IGF-2)

Adipose tissue: leptin · adiponectin · resistin

Skeleton: Osteocalcin

Kidney: JGA (renin) · peritubular cells (EPO) · calcitriol · prostaglandin

Heart: Natriuretic peptide (ANP, BNP)

endocrine navs: anat/physio/dev/hormones, noncongen/congen/neoplasia, symptoms+signs/eponymous, proc

v • d • e Peptides: neuropeptides

Hypothalamic	Somatostatin • CRH • GnRH • GHRH • Orexins • TRH • POMC (ACTH, MSH, Lipotropin)

Gastrointestinal hormones	Cholecystokinin • Gastric inhibitory polypeptide • Gastrin • Motilin • Secretin • Vasoactive intestinal peptide

Other hormones	Calcitonin • Oxytocin • Vasopressin

Other	Angiotensin • Bombesin • Calcitonin gene-related peptide • Carnosine • Cocaine and amphetamine regulated transcript • Delta sleep-inducing peptide • FMRFamide • Galanin • Galanin-like peptide • Gastrin releasing peptide • Kinins (Bradykinin, Tachykinins ) • Neuromedin (B, N, S, U) • Neuropeptide S • Neuropeptide Y • Neurophysins • Neurotensin • Opioid peptides (Dynorphin, Endomorphin, Endorphin, Enkephalin, Nociceptin, Opiorphin) • Pancreatic polypeptide • Pituitary adenylate cyclase activating peptide • VGF

v • d • e Neurotransmitters

Amino acids	Alanine • Aspartate • Cycloserine • DMG • GABA • Glutamate • Glycine • Hypotaurine • Kynurenic Acid (Transtorine) • NAAG (Spaglumic Acid) • NMG (Sarcosine) • Serine • Taurine • TMG (Betaine)

Endocannabinoids	2-AG • 2-AGE (Noladin Ether) • AEA (Anandamide) • NADA • OAE (Virodhamine) • Oleamide

Gasotransmitters	Carbon Monoxide • Hydrogen Sulfide • Nitric Oxide • Nitrous Oxide

Monoamines	Dopamine • Epinephrine (Adrenaline) • Melatonin • Norepinephrine (Noradrenaline) • Normelatonin • Serotonin (5-HT)

Neuropeptides	See here for more details.

Purines	Adenosine • ADP • AMP • ATP

Trace amines	3-ITA • 5-MeO-DMT • Bufotenin • DMT • NMT • Octopamine • Phenethylamine • Synephrine • Thyronamine • Tryptamine • Tyramine

Others	1,4-BD • Acetylcholine • GBL • GHB • Histamine

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thyrotropin-releasing hormone

Contents

Synthesis

History

Chemical properties

Clinical significance

See also

References