The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2026-01-25. Anything still debated is marked as such rather than presented as settled.
Pharmacologically, melanotan-2 behaves as a non-selective agonist across the melanocortin receptor family. Binding at MC1R on dermal melanocytes promotes eumelanin synthesis, which underlies the tanning response described in early human work. Activity at the centrally expressed MC4R receptor is associated with reported effects on appetite and erectile function. Because the peptide does not discriminate strongly among receptor subtypes, attributing any single observed effect to one receptor pathway is generally not possible without selective antagonists or receptor knockout models.
Research interest has centred on photoprotection and pigmentation, with a smaller body of work on appetite and sexual function. Published human data remain limited to small, frequently uncontrolled studies, and the compound has never received marketing approval from a national medicines regulator. Most laboratory work treats it as a pharmacological tool for probing melanocortin signalling in cell culture or animal models. Whether pigmentation changes observed in people translate into measurable protection against ultraviolet-induced DNA damage remains an open question.
Structurally, Melanotan-2 retains the core recognition motif of alpha-melanocyte-stimulating hormone while adding a lactam bridge that links two side chains and constrains the molecule into a ring. This modification lowers susceptibility to enzymatic degradation. The compound acts as an agonist at melanocortin receptors, particularly subtypes associated with melanin production. Because the same receptor family influences several physiological processes, researchers note that its activity is not confined to pigmentation alone. Receptor selectivity continues to be examined in published studies.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its sequence incorporates modified residues that increase potency and extend biological activity relative to the native hormone. The compound binds receptors of the melanocortin family and is examined mainly in laboratory research. It does not occur naturally and exists only as a manufactured chemical entity produced by solid-phase synthesis.
| Property | Value | Notes |
|---|---|---|
| Common synonyms | Melanotan II; MT-II; N-acetyl-norleucyl-cyclo[Asp-His-D-Phe-Arg-Trp-Lys] amide | Naming follows peptide convention; the numeral distinguishes it from melanotan-1 |
| Molecular formula | C50H69N15O9 | Includes the lactam bridge; no counter-ion assumed |
| Monoisotopic mass | 1023.53 Da | Free base; salts and counter-ions shift the observed value |
| Appearance | White to off-white lyophilised powder | Batch-to-batch colour variation is not itself proof of impurity |
| Typical analytical method | RP-HPLC purity determination with ESI-MS identity confirmation | Retention time alone does not establish sequence identity |
Receptor-binding studies classify melanotan II as a non-selective melanocortin agonist. It interacts with MC1R, MC3R, MC4R and MC5R, with reported affinities in the low nanomolar range and no strong subtype preference. Activation of MC1R on dermal melanocytes shifts pigment synthesis toward eumelanin, the dark polymer deposited in melanosomes and transferred to keratinocytes. Because the same peptide engages MC4R in the hypothalamus, it also appears in animal work on food intake and erectile response, which is why it is discussed in both pigment and metabolic research. Which receptor populations dominate after systemic exposure in humans is not fully established.
Published pharmacokinetic information is limited and comes mainly from small studies rather than registrational trials. Plasma half-life is usually described as short, on the order of tens of minutes, followed by rapid tissue distribution and clearance of the intact peptide. Metabolites and low concentrations of parent compound have been reported in urine, a detail relevant to anti-doping and forensic testing. Whether repeated exposure changes receptor sensitivity or clearance over time remains an open question. Values differ noticeably between analytical assays, so published numbers should be read as approximate rather than definitive.
Published human data come mostly from small, short studies rather than large controlled trials. Reported outcomes include increased skin pigmentation and, in some reports, effects on appetite and libido, but sample sizes are small and follow-up is limited. Whether long-term use produces durable pigment changes or adverse effects is not established. Because products sold outside pharmacies are not standardized, the actual content of any given vial is often unknown. Independent testing of such material is uncommon.
Melanotan II is a synthetic cyclic heptapeptide analog derived from the core sequence of alpha-melanocyte-stimulating hormone. Researchers at the University of Arizona synthesized it during the 1980s while studying pigmentation and appetite signaling. The compound is not an approved medicine in any major jurisdiction and appears mainly in laboratory and research-chemical settings. Its structure incorporates a lactam bridge between side chains, which constrains the ring and slows enzymatic breakdown relative to the natural hormone.
== Structure == The parenchyma is the functional parts of an organ, or of a structure such as a tumour in the body. This is in contrast to the stroma, which refers to the structural tissue of organs or of structures, namely, the connective tissues.
=== Fracture risk === Evidence from longitudinal, cross-sectional, and prospective cohort studies suggests an association between SSRI usage at therapeutic doses and a decrease in bone mineral density, as well as increased fracture risk, a relationship that appears to persist even with adjuvant bisphosphonate therapy. However, because the relationship between SSRIs and fractures is based on observational data as opposed to prospective trials, the phenomenon is not definitively causal. There also appears to be an increase in fracture-inducing falls with SSRI use, suggesting the need for increased attention to fall risk in elderly patients using the medication. The loss of bone density does not appear to occur in younger patients taking SSRIs.
Enfortumab vedotin, sold under the brand name Padcev, is an antibody-drug conjugate used for the treatment of urothelial cancer. It is a nectin-4-directed antibody and microtubule inhibitor conjugate. Enfortumab refers to the monoclonal antibody part, and vedotin refers to the payload drug (MMAE) and the linker. The most common side effects include fatigue, peripheral neuropathy (nerve damage resulting in tingling or numbness), decreased appetite, rash, alopecia (hair loss), nausea, altered taste, diarrhea, dry eye, pruritus (itching) and dry skin. The fully humanized antibody was created by scientists at Agensys (part of Astellas) using Xenomice from Amgen; the linker technology holding the antibody and the toxin together was provided by and licensed from Seattle Genetics. The U.S. Food and Drug Administration (FDA) considers it to be a first-in-class medication.
All cells with mitochondria can take up ketones from the blood and reconvert them into acetyl-CoA, which can then be used as fuel in their citric acid cycles, as no other tissue can divert its oxaloacetate into the gluconeogenic pathway in the way that this can occur in the liver. Unlike free fatty acids, ketones can cross the blood–brain barrier and are therefore available as fuel for the cells of the central nervous system, acting as a substitute for glucose, on which these cells normally survive. The occurrence of high levels of ketones in the blood during starvation, a low carbohydrate diet, prolonged heavy exercise, or uncontrolled type 1 diabetes mellitus is known as ketosis, and, in its extreme form, in out-of-control type 1 diabetes mellitus, as ketoacidosis.
=== World War II === Immediately after the start of World War II, Kimon Georgiev sent a letter to Prime Minister Georgi Kyoseivanov, advocating rapprochement with the Soviet Union. During the changes in government in October 1939, Georgiev was received at a two-hour meeting by Tsar Boris III, with whom he discussed the political situation and tried unsuccessfully to secure the release of Damyan Velchev and the other convicted activists of the Military Union. In November 1940, Georgiev supported the Soviet proposal for a mutual aid pact. Apart from the old activists of Zveno, the proposal for the pact is supported only by the Communists, the BZNS-Pladne and some radicals. In January 1941, Kimon Georgiev was among the leaders of almost all the former parties who signed a joint request for an audience with the Tsar, insisting on the preservation of Bulgaria's neutrality. He also expressed this position in a long letter to Prime Minister Bogdan Filov on 11 February, but shortly afterwards the country joined the Tripartite Pact and allowed German troops into Greece. The anti-fascist Zveno members, especially its prominent representative Kimon Georgiev, were reached out to by the Bulgarian Communist Party, which began collaborating with them to free the nation from the fascist tyranny. With the founding of the Fatherland Front in 1942 at Georgi Dimitrov's instigation, Kimon Georgiev and some of his supporters became members of the National Committee.
Sources: en.wikipedia.org
Xenopus egg extract is a lysate that is prepared by crushing the eggs of the African clawed frog Xenopus laevis. It offers a powerful cell-free (or in vitro) system for studying various cell biological processes, including cell cycle progression, nuclear transport, DNA replication and chromosome segregation. It is also called Xenopus egg cell-free system or Xenopus egg cell-free extract.
Romania derives from the local name for Romanian (Romanian: român), which in turn derives from Latin romanus, meaning "Roman" or "of Rome". This ethnonym for Romanians is first attested in the sixteenth century by Italian humanists travelling in Transylvania, Moldavia, and Wallachia. The oldest known surviving document written in Romanian that can be precisely dated, a 1521 letter known as the "Letter of Neacșu from Câmpulung", is notable for including the first documented occurrence of Romanian in a country name: Wallachia is mentioned as Țara Rumânească.
Treatments are available to reduce the severity of some HD symptoms. For many of these treatments, evidence to confirm their effectiveness in treating symptoms of HD specifically are incomplete. As the disease progresses, the ability to care for oneself declines, and carefully managed multidisciplinary caregiving becomes increasingly necessary. Although relatively few studies of exercises and therapies have shown to be helpful to rehabilitate cognitive symptoms of HD, some evidence shows the usefulness of physical therapy, occupational therapy, and speech therapy.
In addition, historical figures in the process of independence in New Granada emerged from the expedition as the astronomer Francisco José de Caldas, the scientist Francisco Antonio Zea, the zoologist Jorge Tadeo Lozano and the painter Salvador Rizo.
Sources: en.wikipedia.org
=== 2021–present: Post-breakup activity and abandoned fourteenth studio album === The 2021 retirement of King Crimson's "Seven-Headed Beast" line-up, and Fripp's subsequent statement that the band had finished, left a certain amount of written/performed King Crimson music unrecorded in the studio, although some of that material had appeared on live recordings from the time. New original songs performed in concert by the band had included "Meltdown", "Radical Action", "Radical Action II", "The Errors", and more. Versions of two Fripp/Jakszyk songs originally intended for King Crimson ("Uncertain Times" and "Separation") had also emerged on Jakszyk's 2020 solo album Secrets and Lies, with participation from Fripp, Harrison, Levin and Collins. Following the most recent retirement of the band, Jakko Jakszyk hinted, suggested and ultimately stated that this material will see formal release as a studio album, the band's first in over twenty years since the release of The Power to Believe. In August 2021, Jakszyk referred to the existence of "about forty to fifty minutes' worth of new (King Crimson) stuff, a number of songs I've co-written with Robert and some instrumental things he's written.
November 2: Law on the labor of children, underage girls, and women in industrial establishments. November 30: Law on the practice of medicine: midwives are prohibited from prescribing medication, they may administer smallpox vaccines, and during childbirth, they are forbidden from using instruments and must call a physician or health officer in case of complications. 1893
=== 2. Periodontal ligament === The periodontal ligament is a specialized, vascular, and cellular connective tissue occupying the space between the cementum of the tooth root and the alveolar bone socket. It is primarily composed of dense collagen fiber bundles, known as Sharpey's fibers, which anchor the tooth to the surrounding alveolar bone. Functionally, the periodontal ligament acts as a shock absorber during mastication, provides proprioceptive sensory input, and contributes to the nutritional and reparative capacity of the periodontal tissues. In periodontitis, progressive destruction of periodontal ligament fibers occurs in association with apical migration of the junctional epithelium, resulting in increased tooth mobility.
== Distribution == In humans, sarcosine is found at relatively low concentrations in the extracellular compartment, mitochondria, and peroxisomes. Tissues with measurable sarcosine concentrations include skeletal muscle and the prostate gland. Its cellular levels are tightly regulated by the balance between GNMT-mediated synthesis and SARDH/PIPOX-mediated catabolism.
Boyle, Peter; Nigel Gray, Jack Henningfield, John Seffrin and Witold Zatonski, Tobacco: Science, Policy and Public Health, Oxford University Press, second edition, 2010, 776 pages (ISBN 9780199566655). Brandt, Allan. The Cigarette Century: The Rise, Fall, and Deadly Persistence of the Product That Defined America (2007). online Brooks, Jerome E. The Mighty Leaf: The Story of Tobacco (Little, Brown, 1952) Burns, Eric. The Smoke of the Gods: A Social History of Tobacco (Temple University Press, 2007) online Cochran, Sherman. Big Business in China: Sino-Foreign Rivalry in the Cigarette Industry, 1890-1930 (Harvard UP, 1980). Corti, Count. (1931) A history of smoking (Bracken 1996 reprint; 1931) online Durden, Robert F. The Dukes of Durham, 1865-1929 (1975) online Enstad, Nan. Cigarettes, Inc.: An Intimate History of Corporate Imperialism (U of Chicago, 2018) excerpt Gately, Iain. Tobacco: A Cultural History of How an Exotic Plant Seduced Civilization (2003) Goodman, Jordan, ed. Tobacco in History and Culture. An Encyclopedia (2 vol, Gage Cengage, 2005)online Hahn, Barbara. Making Tobacco Bright: Creating an American Commodity, 1617–1937 (Johns Hopkins University Press, 2011). examines how marketing, technology, and demand caused the dominance of Bright Flue-Cured Tobacco. Hannah, Leslie. "The Whig Fable of American Tobacco, 1895-1913," Journal of Economic History 66#1 (2006), pp. 42–73 online, argues most historians misinterpret the company. Harrald, Chris. The cigarette book: the history and culture of smoking (2010) online Heimann, Robert K.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, containing seven amino acids with a lactam ring and a D-configured phenylalanine residue. It is supplied as a lyophilised powder for laboratory research.
The natural hormone is a linear tridecapeptide that is rapidly degraded in circulation. Melanotan-2 is shortened, cyclised, N-terminally acetylated, and carries a D-amino acid substitution, all of which slow enzymatic breakdown.
No national medicines regulator has approved melanotan-2 for therapeutic or cosmetic use. In several jurisdictions it is treated as an unapproved prescription medicine, and its legal classification differs from country to country.
It is a synthetic cyclic heptapeptide and an analogue of alpha-melanocyte-stimulating hormone. The molecule is produced by chemical synthesis rather than extracted from a biological source.