Growth hormone releasing hormone

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Growth hormone releasing hormone
Identifiers
Symbol	GHRH GRF, GHRF
HUGO	4265
Entrez	2691
OMIM	139190
RefSeq	NM_021081
UniProt	P01286
Other data
Locus	Chr. 20 p12 or q11.2-q12

Growth-hormone-releasing hormone (GHRH), also known as growth-hormone-releasing factor (GRF or GHRF) or somatocrinin, is a 44-amino acid peptide hormone produced in the arcuate nucleus of the hypothalamus.

GHRH is released from neurosecretory nerve terminals of these arcuate neurons, and is carried by the hypothalamo-hypophysial portal circulation to the anterior pituitary gland where it stimulates growth hormone (GH) secretion. GHRH also stimulates the production of GH. GHRH is released in a pulsatile manner, stimulating similar pulsatile release of GH. In addition, GHRH also promotes slow-wave sleep directly. ^[1]

[edit] Relationship to somatostatin

The actions of GHRH are opposed by another hypothalamic hormone, somatostatin, also known as "growth-hormone-inhibiting hormone" (GHIH).

Somatostatin is released from neurosecretory nerve terminals of periventricular somatostatin neurons, and is carried by the hypothalamo-hypophysial portal circulation to the anterior pituitary where it inhibits GH secretion by hyperpolarising the somatotropes.

Somatostatin and GHRH are secreted in alternation, giving rise to the markedly pulsatile secretion of GH. However recently it had been discovered that somatostatin does not affect the secretion of GH.^[2]

[edit] Sequence

The amino acid sequence of GHRH is:

Tyr - Ala - Asp - Ala - Ile - Phe - Thr - Asn - Ser - Tyr - Arg - Lys - Val - Leu - Gly - Glu - Leu - Ser - Ala - Arg - Lys - Leu - Leu - Gln - Asp - Ile - Met - Ser - Arg - Glu - Gln - Gly - Glu - Ser - Asn - Gln - Glu - Arg - Gly - Ala - Arg - Ala - Arg - LeuNH2

[edit] References

^ Obál F, Krueger J (2001). "The somatotropic axis and sleep.". Rev Neurol (Paris) 157 (11 Pt 2): S12-5. PMID 11924022.
^ Dimaraki E, Jaffe C, Demott-Friberg R, Russell-Aulet M, Bowers C, Marbach P, Barkan A (2001). "Generation of growth hormone pulsatility in women: evidence against somatostatin withdrawal as pulse initiator.". Am J Physiol Endocrinol Metab 280 (3): E489-95. PMID 11171604. Paper