Melanotropin Release Inhibiting Hormone

Melanostatin
other names	Melanotropin release-inhibiting factor, neuropeptide Y, NPY
Mass / length primary structure	36 amino acids , 4,245 Da
Identifier
External IDs	UniProt : P69102 ;
	Orthologist ( Rana temporaria )
Entrez	NV
UniProt	P69102 ;
PubMed search	NV

Melanotropin Release Inhibiting Hormone ( MIH ), also known as melanostatin , is a neuropeptide made up of three amino acids. It was discovered in the early 1960s.

The name comes from the original experiment with live rats. When the MIH was injected into rats, it prevented the release of melanotropin (MSH) from the pituitary gland . MIH has been isolated from the hypothalamus .

The primary structure of the human peptide consists of three amino acids (Pro-Leu-Gly-NH ₂ ) with a molecular mass of 300.36 Da . The PLG amide is formed when oxytocin is cleaved by an exopeptidase and forms the carboxy-terminal tripeptide of oxytocin. Tyrosyl-Prolyl-Leucyl-Glycine-Amide (T-MIH) from bovine hypothalami cannot arise from human oxytocin, as this contains the amino acid cysteine instead of tyrosine at this position.

Doubts about the release inhibiting hormone function

The releasing hormones of the hypothalamus are released in the eminentia mediana and reach the adenohypophysis (anterior pituitary lobe) in the blood via the hypothalic-pituitary portal system. There, the ACTH is released almost exclusively from the joint preliminary stage of ACTH and MSH (the proopiomelanocortin , POMC). On the other hand, MSH is formed in the interstitial lobe of POMC. Oxytocin or a cleavage product of oxytocin cannot get from the hypothalamus via the portal system into the pituitary lobe. Oxytocin (like vasopressin ) is stored in nerve endings in the neurohypophysis (posterior lobe of the pituitary gland), which is directly adjacent to the intermediate lobe . It cannot be said whether the breakdown product exists and gets into the intermediate lobe. MIH was isolated from the hypothalamus rather than the pituitary gland.

The more recent literature assigns the MIH a role as a regulator of MSH release in the brain itself. MSH is involved in the regulation of food intake in the brain. MSH binds to the MSH receptor on nerve cells that form and release neuropeptide Y (NPY neurons). Neuropeptide Y was also found to be melanostatin.

Individual evidence

↑ Celis ME, Taleisnik S, Walter R: Regulation of formation and proposed structure of the factor inhibiting the release of melanocyte-stimulating hormone . In: Proc. Natl. Acad. Sci. USA . 68, No. 7, 1971, pp. 1428-1433. PMID 5283931 . PMC 389210 (free full text).

literature

Bernhard Kleine: Hormones and the hormonal system. Springer Verlag 2007, ISBN 3-540-377026 .

[1] Celis ME, Taleisnik S, Walter R: Regulation of formation and proposed structure of the factor inhibiting the release of melanocyte-stimulating hormone . In: Proc. Natl. Acad. Sci. USA . 68, No. 7, 1971, pp. 1428-1433. PMID 5283931 . PMC 389210 (free full text).