The short version of melanocortin receptor fits in a sentence. The long version — which is the one that helps — is below.
Reviewed 2025-12-18. Anything still debated is marked as such rather than presented as settled.
Early published reports described melanotan-2 as a tanning agent without sun protection, which means darkening is not the same as protection against ultraviolet radiation. Later studies explored the peptide in erectile dysfunction, hemorrhagic shock, and some skin conditions. No regulator in the United States or Europe has approved it for clinical use. Many products labelled melanotan-2 are sold without approval and their identity and purity are unverified. Its long-term safety in humans remains an open question.
Melanotan-2, also written Melanotan II, is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence is Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, and the lactam bridge between the aspartate and lysine side chains constrains the peptide into a ring. This structural change increases receptor affinity and metabolic stability relative to the native hormone. The compound was created in the 1980s as a research tool for studying pigmentation biology.
Melanocytes are the pigment-producing cells of the skin, and they carry melanocortin-1 receptors on their surface. When the receptor is activated, cyclic adenosine monophosphate rises inside the cell and raises the activity of enzymes such as tyrosinase, which increases melanin output. Melanotan-2 binds melanocortin-1 receptors in vitro and in animal models, and this binding is generally described as the basis for the tanning effect. Other receptors account for different effects: melanocortin-4 receptors contribute to appetite and erectile signalling, while melanocortin-3 and melanocortin-5 receptors contribute to energy balance and exocrine function.
Receptor studies place melanotan-2 among non-selective melanocortin agonists, binding MC1R, MC3R, MC4R and MC5R rather than a single subtype. Activation of MC1R on cutaneous melanocytes raises tyrosinase activity and shifts pigment synthesis toward eumelanin, which is darker and more photostable than pheomelanin. Central receptors, particularly MC4R, are associated with appetite suppression and with reported effects on sexual function. Because subtype selectivity is low, the same molecule engages pigment, metabolic and vascular pathways at once, and this breadth is a common explanation offered for the range of adverse events described in user reports.
No regulatory authority has approved melanotan-2 for human use, and several countries classify it as a prescription-only or controlled substance, which restricts lawful supply. Material sold online is generally labelled as a research chemical and is not required to meet pharmaceutical standards of identity or purity. Published human data consist mainly of small uncontrolled studies, case reports and adverse-event notifications, so the evidence base is descriptive rather than confirmatory. Whether repeated melanocyte stimulation alters long-term naevus behaviour remains an open question that no completed trial has resolved.
| Property | Value | Notes |
|---|---|---|
| Compound class | Synthetic cyclic heptapeptide | Alpha-MSH analogue containing a D-phenylalanine residue |
| Molecular formula | C50H69N15O9 | Average molecular mass approximately 1024.2 g/mol |
| Appearance | White to off-white lyophilised powder | Normally supplied as a freeze-dried solid in a sealed vial |
| Solubility | Freely soluble in water and polar solvents | Dissolves readily in aqueous buffers and in alcohol-water mixtures |
| Receptor targets | MC1R, MC3R, MC4R, MC5R | Acts as a non-selective melanocortin receptor agonist |
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.
Melanotan II is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, corresponding to a molecular formula of C50H69N15O9 and a monoisotopic mass near 1024 daltons. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, a peptide hormone produced by cleavage of proopiomelanocortin. A lactam bridge between the aspartate and lysine side chains closes the ring, and the C-terminal amide removes a free carboxyl group. Both modifications increase resistance to enzymatic degradation compared with the linear parent hormone. Four substitutions distinguish it from afamelanotide, the linear analogue studied under the name melanotan I.
The compound emerged from research programs in the 1980s that examined analogues of alpha-melanocyte-stimulating hormone for pigmentation and photoprotection. Investigators modified the native sequence to extend activity duration and potency. A related analogue, afamelanotide, was developed within the same broad line of inquiry and eventually gained approval in certain jurisdictions for a rare light-sensitivity condition. Melanotan-2 itself did not progress through the same regulatory route and has no approved therapeutic indication.
Melanocortin receptors comprise five subtypes with distinct tissue distributions and functions. Melanotan-2 is described in the literature as a non-selective agonist that engages several of these subtypes, including MC1R, MC3R, MC4R, and MC5R. MC1R is the subtype most directly linked to melanin production in skin cells. Because the compound is not subtype-selective, its observed effects in experimental settings are generally attributed to activity across multiple receptor pathways rather than to a single target.
=== Legal status === In 2017, inotuzumab ozogamicin was approved by the European Commission and the US Food and Drug Administration for the treatment of adults with relapsed or refractory CD22-positive B-cell precursor acute lymphoblastic leukemia under the brand name Besponsa (Pfizer/Wyeth).
=== Oxytocics === Certain lysergamides like ergometrine and methylergometrine are used clinically as oxytocic agents. The oxytocic effects of these drugs are thought to most likely be mediated by agonism of serotonin 5-HT2 receptors in uterine smooth muscle tissue.
=== In popular culture === Invented in 1949, and marketed and sold commercially by Hasbro in 1952, Mr. Potato Head is an American toy that consists of a plastic potato and attachable plastic parts, such as ears and eyes, to make a face. It was the first toy ever advertised on television. In the 2015 science fiction film The Martian, the protagonist, a stranded astronaut and botanist named Mark Watney, cultivates potatoes on Mars using Martian soil fertilized with frozen feces.
Through franchise partnership with Dubai-based Apparel Group, Tim Hortons entered the United Arab Emirates in 2011 with locations in Abu Dhabi, Dubai and Fujairah. The first opening took place in September 2011. As of December 2013, Tim Hortons has nineteen stores in the United Arab Emirates, two in Oman and two in Saudi Arabia. They plan to open up to one hundred and twenty stores over the next five years in the Persian Gulf area, with a focus on Qatar, Bahrain, Kuwait, Oman, and the United Arab Emirates. Kuwait has Tim Hortons at The Gate Mall in Egaila, at Promenade Mall in Hawalli, and at The Avenues Mall at Al Rai.
Sources: en.wikipedia.org
== Career == Sinclair met Massachusetts Institute of Technology professor Leonard P. Guarente in 1993. Guarente had studied yeast as a model of aging, and after meeting him, Sinclair interviewed for a post-doc position in Guarente's lab. He worked as a postdoctoral researcher for Guarente for four years and in 1999 he was hired at Harvard Medical School. In 2004, Sinclair met with the philanthropist Paul F. Glenn who donated $5 million to Harvard to establish the Paul F. Glenn Laboratories for the Biological Mechanisms of Aging at Harvard, of which Sinclair became the founding director. In 2004, Sinclair founded Sirtris Pharmaceuticals along with Andrew Perlman, Christoph Westphal, Richard Aldrich, Richard Pops, and Paul Schimmel. Sirtris was focused on developing Sinclair's research into activators of sirtuins, work that began in the Guarente lab. The company was specifically focused on resveratrol formulations and derivatives as activators of the SIRT1 enzyme; Sinclair became known for making statements about resveratrol like: "(It's) as close to a miraculous molecule as you can find. ... One hundred years from now, people may be taking these molecules on a daily basis to prevent heart disease, stroke, and cancer." Most of the anti-aging field was more cautious, especially with regard to what else resveratrol might do in the body and its lack of bioavailability. The company went public in 2007 and was subsequently purchased by and made a subsidiary of GlaxoSmithKline in 2008 for $720 million.
== See also == Better Life Index Broad measures of economic progress Gross National Happiness Gross National Well-being Happiness economics Human Development Index Humanistic economics Job satisfaction Social determinants of health Social determinants of health in poverty Social determinants of mental health World Values Survey
Breó (meaning 'glow' in Irish) was a wheat beer; it cost around IR£5 million to develop. A brewing byproduct of Guinness, Guinness Yeast Extract (GYE), was produced until the 1950s. In the UK, a HP Guinness Sauce was manufactured by Heinz and available as of 2013. In March 2010, Guinness began test marketing Guinness Black Lager, a new black lager, in Northern Ireland and Malaysia. As of September 2010, Guinness Black Lager is no longer readily available in Malaysia. In October 2010, Guinness began selling Foreign Extra Stout in 4 packs of bottles in the United States.
June 13 2026 UFL season: In American football, the Louisville Kings defeat the DC Defenders, 27–20, to win their first United Bowl championship in their inaugural year in the United Football League. 2026 NBA Finals: In basketball, the New York Knicks defeat the San Antonio Spurs 94–90 in Game 5 of the NBA Finals to win their first championship title since 1973 and their third overall. They also become the first team out of the four major league teams in the New York metropolitan area to win a championship since the New York Giants in 2011. Trump's name is removed from the Kennedy Center. June 14 Iran war: Trump and Iran announce that they have reached an agreement to end the war and reopen the Strait of Hormuz. Trump also says that he has authorized the lifting of the US naval blockade of Iran. The US military later clarifies that the blockade will remain in effect until the agreement is signed on 19 June. 2026 NBA Finals: Police arrest 63 people outside Madison Square Garden in New York City after 10 police officers were injured during celebrations of the New York Knicks winning the NBA Finals. Gunshots are reported overnight on 42nd Street and Broadway in New York City with one teen shot and several buses being damaged during celebrations. The UFC Freedom 250 event, named after the 250th anniversary of the U.S. Declaration of Independence, is held on the South Lawn of the White House. The event coincides with Trump's 80th birthday.
The breeder reactor as its name implies creates larger quantities of 239Pu or 233U (the fissile isotopes) than it consumes. The Clean And Environmentally Safe Advanced Reactor (CAESAR), a nuclear reactor concept that would use steam as a moderator to control delayed neutrons, will potentially be able to use 238U as fuel once the reactor is started with Low-enriched uranium (LEU) fuel. This design is still in the early stages of development.
Sources: en.wikipedia.org
== Names == Dapagliflozin is the international nonproprietary name (INN), and the United States Adopted Name (USAN). The fixed-dose combination product, dapagliflozin/metformin extended-release, is sold under the brand name Xigduo XR. In July 2016, the fixed-dose combination of saxagliptin and dapagliflozin was authorized for medical use in the European Union and is sold under the brand name Qtern. The combination drug was approved for medical use in the United States in February 2017, where it also is sold under the brand name Qtern. In May 2019, the fixed-dose combination of dapagliflozin, saxagliptin, and metformin hydrochloride as extended-release tablets was approved in the United States to improve glycemic control in adults with type 2 diabetes when used in combination with diet and exercise. The FDA granted the approval of Qternmet XR to AstraZeneca. The combination drug was authorized for use in the European Union in November 2019, and is sold under the brand name Qtrilmet.
Nine mobile detachments (Panjin, Liaoning; Shenyang, Liaoning; Bayisingtu, Inner Mongolia; Tianjin; Dingzhou, Hebei; Baoding, Hebei; Jinzhong, Shanxi; Zhengzhou, Henan; Pingliang, Gansu); Three Special Operations detachments (Beijing; Tianjin; Shijiazhuang); Two Transportation detachments (Beijing and Xi’an, Shaanxi); One Engineering/Chemical Defence detachment (Huludao, Liaoning); One Helicopter detachment with 3 Groups
=== General and cited references === Carnegie Library of Pittsburgh. Science and Technology Department. The Handy Science Answer Book. Pittsburgh: The Carnegie Library, 1997. ISBN 978-0-7876-1013-5. Perham, Nick; Moore, Simon C.; Shepherd, Jonathan; Cusens, Bryany (2007). "Identifying drunkenness in the night-time economy". Addiction. 102 (3): 377–80. doi:10.1111/j.1360-0443.2006.01699.x. PMID 17298644. Taylor, L., and S. Oberman. Drunk Driving Defense, 6th edition. New York: Aspen Law and Business, 2006. ISBN 978-0-7355-5429-0.
Tolerance and dependence can develop with long-term use of prazepam, and upon cessation or reduction in dosage, then a benzodiazepine withdrawal syndrome may occur with symptoms such as tremulousness, dysphoria, psychomotor agitation, tachycardia and sweating. In severe cases, hallucinations, psychosis and seizures can occur. Withdrawal-related psychosis is generally unresponsive to antipsychotic mediations. The risk and severity of the withdrawal syndrome increases the higher the dose and the longer prazepam is taken for. Tolerance, dependence and withdrawal problems may be less severe than with other benzodiazepines, such as diazepam. It may be because tolerance is slower to develop with prazepam than with other benzodiazepines. Abrupt or over-rapid discontinuation of prazepam after long-term use, even at low dosage, may result in a protracted withdrawal syndrome. Benzodiazepines can induce serious problems of addiction, which is one of the main reasons for their use being restricted to short-term use. A survey in Senegal found that the majority of doctors believed that their training in this area was generally poor. It was recommended that national authorities take urgent action regarding the rational use of benzodiazepines. Almost one-fifth of doctors ignored prescription guidelines regarding short-term use of benzodiazepines, and almost three-quarters of doctors regarded their training and knowledge of benzodiazepines to be inadequate. More training regarding benzodiazepines has been recommended for doctors.
Sources: en.wikipedia.org
No. It is a laboratory-made peptide, while the natural hormone is alpha-melanocyte-stimulating hormone, a longer peptide produced by the pituitary gland and by skin cells. Melanotan-2 mimics only a short active region of that hormone and contains non-natural residues such as D-phenylalanine.
No approved regulatory indication exists in major markets. An approval exists for a different peptide, afamelanotide, which is used for a rare photosensitivity disorder called erythropoietic protoporphyria. Melanotan-2 itself remains a research compound with no cleared clinical role.
Melanocortin-1 receptors on melanocytes are the receptor most closely linked to pigment production. The peptide is not selective, however, and also activates melanocortin-3, melanocortin-4, and melanocortin-5 receptors. That lack of selectivity is the usual explanation offered for both its range of observed effects and its off-target effects.
No regulatory agency has authorised melanotan-2 as a medicine for any indication. It circulates mainly as a research chemical or through unregulated channels. As a result, identity, purity and content are not independently guaranteed.