関: melanocyte-stimulating hormone、melanotropin、MSH

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2014/01/15 09:03:12」(JST)

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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.

Function[edit]

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[edit]

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[edit]

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), new scars become hyperpigmented, whereas older ones do not 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[edit]

Melanocyte-stimulating hormone belongs to a group called the melanocortins. This group includes ACTH, alpha-melanocyte-stimulating hormone (α-MSH), beta-melanocyte-stimulating hormone (β-MSH) and gamma-melanocyte-stimulating hormone (γ-MSH); these peptides are all cleavage products of a large precursor peptide called pro-opiomelanocortin (POMC). α-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[edit]

Synthetic analogs of α-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.

Afamelanotide (formerly CUV1647) is being investigated as a method of photoprotection in patients with erythropoietic protoporphyria, polymorphous light eruption, actinic keratosis and squamous cell carcinoma (a form of skin cancer).^[1]

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 is currently under development by a New Jersey company for its aphrodisiac effects. These effects are mediated by actions in the hypothalamus on neurons that express MC3R and MC4R receptors.

References[edit]

^ Clinuvel FAQs
^ 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. Cite uses deprecated parameters (help)

External links[edit]

Melanocyte-Stimulating Hormones at the US National Library of Medicine Medical Subject Headings (MeSH)
Clinuvel Pharmaceuticals
Palatin Technologies

English Journal

Cellular insulin resistance disrupts hypothalamic mHypoA-POMC/GFP neuronal signaling pathways.

Nazarians-Armavil A, Chalmers JA, Lee CB, Ye W, Belsham D.SourceA Nazarians-Armavil, Physiology, University of Toronto, Toronto, Canada.
The Journal of endocrinology.J Endocrinol.2013 Oct 17. [Epub ahead of print]
Proopiomelanocortin (POMC) neurons play a central role in the maintenance of whole body energy homeostasis. This balance requires proper regulation of POMC neurons by metabolic hormones, such as insulin. However, the heterogeneous cellular population of the intact hypothalamus presents challenges fo
PMID 24134870

Endogenous opiates and behavior: 2012.

Bodnar RJ.SourceDepartment of Psychology and Neuropsychology Doctoral Sub-Program, Queens College, City University of New York, Flushing, NY 11367, United States. Electronic address: richard.bodnar@qc.cuny.edu.
Peptides.Peptides.2013 Oct 12. pii: S0196-9781(13)00333-1. doi: 10.1016/j.peptides.2013.10.001. [Epub ahead of print]
This paper is the thirty-fifth consecutive installment of the annual review of research concerning the endogenous opioid system. It summarizes papers published during 2012 that studied the behavioral effects of molecular, pharmacological and genetic manipulation of opioid peptides, opioid receptors,
PMID 24126281

Aerobic training (AT) is more effective than aerobic plus resistance training (AT+RT) to improve anorexigenic/orexigenic factors in obese adolescents.

Carnier J, de Mello MT, Ackel-DElia C, Corgosinho FC, Campos RM, Sanches Pde L, Masquio DC, Bueno CR Jr, Ganen Ade P, Martins AC, Caranti DA, Tock L, Clemente AP, Tufik S, Dâmaso AR.SourcePrograma de Pós-Graduação em Nutrição, Universidade Federal de São Paulo - UNIFESP, Brazil. junecarnier@gmail.com
Appetite.Appetite.2013 Oct;69:168-73. doi: 10.1016/j.appet.2013.05.018. Epub 2013 Jun 10.
BACKGROUND: The regulation of energy balance is influenced by physical exercise. Although some studies show a stimulation of hormones related to food intake, others show that exercise provides satiety.AIM: The aim of this study was to compare the effects of aerobic training (AT) and aerobic plus res
PMID 23764241

Japanese Journal

Influence of adrenomedullin 2/intermedin gene polymorphism on blood pressure, renal function and silent cerebrovascular lesions in Japanese : the Ohasama study

HIROSE Takuo,TOTSUNE Kazuhito,NAKASHIGE Yukiko,METOKI Hirohito,KIKUYA Masahiro,OHKUBO Takayoshi,HARA Azusa,SATOH Michihiro,INOUE Ryusuke,ASAYAMA Kei,KONDO Takeo,KAMIDE Kei,KATSUYA Tomohiro,OGIHARA Toshio,IZUMI Shin-Ichi,RAKUGI Hiromi,TAKAHASHI Kazuhiro,IMAI Yutaka
Hypertension research : clinical and experimental : official journal of the Japanese Society of Hypertension 34(12), 1327-1332, 2011-12-01
NAID 10030278155

Decreased expression of adrenomedullin 2/intermedin in the kidney of hypertension or renal failure ; Possible involvement in chronic kidney disease

TAKAHASHI Kazuhiro,HIROSE Takuo,MORI Nobuyoshi,MORI Takefumi,KOHZUKI Masahiro,IMAI Yutaka,TOTSUNE Kazuhito
Peptide science : proceedings of the ... Japanese Peptide Symposium 2010, 75, 2011-03-01
NAID 10028237300