Melanocyte-stimulating hormone
proopiomelanocortin (adrenocorticotropin/ beta-lipotropin/ alpha-melanocyte stimulating hormone/ beta-melanocyte stimulating hormone/ beta-endorphin)
Identifiers
Symbol POMC
Entrez 5443
HUGO 9201
OMIM 176830
RefSeq NM_000939
UniProt P01189
Other data
Locus Chr. 2 p23
Melanocyte-stimulating hormone
Clinical data
Pregnancy cat.  ?
Legal status  ?
Identifiers
ATC code  ?
ChEMBL CHEMBL214332 YesY
Chemical data
Formula C77H109N21O19S
Mol. mass 1664.9
 N(what is this?)  hormone (verify)


The melanocyte-stimulating hormones (collectively referred to as MSH or intermedins) are a class of peptide hormones that are produced by cells in the intermediate lobe of the pituitary gland. Synthetic analogs of these naturally occurring hormones have also been developed and researched.

Contents

Function

They stimulate the production and release of melanin (melanogenesis) by melanocytes in skin and hair. MSH signals to the brain have effects on appetite and sexual arousal.

In amphibians

In some animals (such as the claw-toed frog Xenopus laevis) production of MSH is increased when the animal is in a dark location. This causes pigment to be dispersed in pigment cells in the toad's skin, making it become darker, and harder for predators to spot. The pigment cells are called melanophores and therefore, in amphibians, the hormone is often called melanophore-stimulating hormone.

In humans

An increase in MSH will cause a darkening in humans too. Melanocyte-stimulating hormone increases in humans during pregnancy. This, along with increased estrogens, causes increased pigmentation in pregnant women. Cushing's syndrome due to excess adrenocorticotropic hormone (ACTH) may also result in hyperpigmentation, such as acanthosis nigricans in the axilla. Most people with primary Addison's have darkening (hyperpigmentation) of the skin, including areas not exposed to the sun; characteristic sites are skin creases (e.g. of the hands), nipple, and the inside of the cheek (buccal mucosa), also old scars may darken. This occurs because melanocyte-stimulating hormone (MSH) and adrenocorticotropic hormone (ACTH) share the same precursor molecule, Pro-opiomelanocortin (POMC).

Different levels of MSH are not the major cause of racial variation in skin colour. However, in many red headed people, and other people who do not tan well, there are variations in their hormone receptors, causing them to not respond to MSH in the blood.

See melanocortin receptor for more information.

Structure of MSH

proopiomelanocortin derivatives
POMC
     
γ-MSH ACTH β-lipotropin
         
  α-MSH CLIP γ-lipotropin β-endorphin
       
    β-MSH  

Melanocyte-stimulating hormone belongs to a group called the melanocortins. This group includes ACTH, alpha-MSH, beta-MSH and gamma-MSH; these peptides are all cleavage products of a large precursor peptide called pro-opiomelanocortin (POMC). Alpha-MSH is the most important melanocortin for pigmentation.

The different melanocyte-stimulating hormones have the following amino acid sequences:

α-MSH: Ac-Ser-Tyr-Ser-Met-Glu-His-Phe-Arg-Trp-Gly-Lys-Pro-Val
β-MSH (human): Ala-Glu-Lys-Lys-Asp-Glu-Gly-Pro-Tyr-Arg-Met-Glu-His-Phe-Arg-Trp-Gly-Ser-Pro-Pro-Lys-Asp
β-MSH (porcine): Asp-Glu-Gly-Pro-Tyr-Lys-Met-Glu-His-Phe-Arg-Trp-Gly-Ser-Pro-Pro-Lys-Asp
γ-MSH: Tyr-Val-Met-Gly-His-Phe-Arg-Trp-Asp-Arg-Phe-Gly

Synthetic MSH

Synthetic analogs of alpha-MSH have been developed for human use. Two of the better known are afamelanotide (melanotan-1) in testing by Clinuvel Pharmaceuticals in Australia and bremelanotide by Palatin Technologies, a New Jersey company.

  • An additional analog called Melanotan II causes enhanced libido and erections in most male test subject and arousal with corresponding genital involvement in most female test subjects.[2] Bremelanotide (formerly PT-141) which stemmed from Melanotan II research was previously under development by the New Jersey company for its aphrodisiac effects. These effects are mediated by actions in the hypothalamus on neurons that express MC3 MC3R and MC4 MC4R receptors.

See also

References

  1. ^ Clinuvel FAQs
  2. ^ Hadley ME (Oct 2005). "Discovery that a melanocortin regulates sexual functions in male and female humans". Peptides 26 (10): 1687–9. doi:10.1016/j.peptides.2005.01.023. PMID 15996790. 

Further reading

External links



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Look at other dictionaries:

  • melanocyte-stimulating hormone — n either of two vertebrate hormones of the pituitary gland that darken the skin by stimulating melanin dispersion in pigment containing cells abbr. MSH called also intermedin, melanophore stimulating hormone, melanotropin …   Medical dictionary

  • Melanocyte-stimulating hormone — Hormone mélanotrope Pour les articles homonymes, voir MSH. L hormone mélanotrope, ou mélanotropine ou mélanocortine (nom le plus utilisé) ou MSH (pour melanocyte stimulating hormone), est une hormone sécrétée par les cellules mélanotropes de l… …   Wikipédia en Français

  • melanocyte-stimulating hormone — melanocyte stimulating hormone. См. интермедин. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) …   Молекулярная биология и генетика. Толковый словарь.

  • melanocyte-stimulating hormone — noun a hormone secreted by the anterior pituitary gland that controls the degree of pigmentation in melanocytes • Syn: ↑MSH • Hypernyms: ↑hormone, ↑endocrine, ↑internal secretion …   Useful english dictionary

  • melanocyte-stimulating hormone — noun Date: 1953 any of several vertebrate hormones of the pituitary gland that darken the skin by stimulating melanin dispersion in pigment containing cells …   New Collegiate Dictionary

  • melanocyte-stimulating hormone — A releasing hormone produced in the mammalian hypophysis and related structures in lower vertebrates. Made up of a MSH (1665 D), the same as amino acids 1 13 of ACTH, and b MSH (18 amino acids, 22 in humans). Causes darkening of the skin by… …   Dictionary of molecular biology

  • melanocyte-stimulating hormone — MSH a hormone synthesized and released by the pituitary gland. In amphibians MSH brings about colour changes in the skin but its physiological role in humans is uncertain …   The new mediacal dictionary

  • melanocyte-stimulating hormone — /meuh lan euh suyt stim yeuh lay ting, mel euh neuh /, Biochem. See MSH. [1950 55] * * * …   Universalium

  • melanocyte-stimulating hormone — melan′ocyte stim ulating hor mone n. biochem. See MSH • Etymology: 1950–55 …   From formal English to slang

  • Гормон Меланоцит-Стимулирующий (Мсг) (Melanocyte-Stimulating Hormone (Msh)) — гормон, секретируемый передней долей гипофиза. У земноводных этот гормон отвечает за изменение окраски кожи, однако его физиологическую роль в организме человека пока что установить не удалось. (Существуют убедительные данные, что МСГ стимулирует …   Медицинские термины

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