melanocortin receptor is one of those subjects where the details matter more than the headlines. This page pulls together the background, the mechanisms, and the practical points readers ask about most.
Last reviewed on 2026-02-11. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan-2 is a synthetic cyclic heptapeptide designed as an analogue of alpha-melanocyte-stimulating hormone. Its sequence incorporates a lactam bridge that constrains the peptide into a ring, which increases resistance to enzymatic breakdown relative to the natural hormone. Researchers at the University of Arizona synthesised the compound in the late 1980s and early 1990s while studying pigmentation pathways. It has never received marketing approval from any national medicines regulator. In the scientific literature it is usually described as a laboratory research reagent rather than a therapeutic product.
The peptide acts as a non-selective agonist at melanocortin receptors, showing affinity for MC1R, MC3R, MC4R and MC5R. Activation of MC1R on melanocytes drives the conversion of tyrosine into melanin and shifts production toward the darker eumelanin form. MC4R signalling in the central nervous system is linked to appetite and energy balance, which helps explain why reduced food intake appeared in early human studies. Effects on MC4R and on vascular tone also account for the erectile responses recorded as unexpected findings in those same trials.
Melanotan-2 is frequently confused with afamelanotide, a linear analogue authorised in the European Union for erythropoietic protoporphyria. The two compounds differ in chain length, ring structure and receptor selectivity, so findings for one cannot be transferred directly to the other. Published controlled human data on melanotan-2 remain sparse, and much of what circulates online derives from small studies or unpublished reports. Questions about effect size, dose-response behaviour and long-term safety therefore remain unresolved.
Melanotan II binds several melanocortin receptor subtypes rather than a single target. MC1R on melanocytes drives melanin synthesis, while MC3R and MC4R participate in energy balance, appetite, and sexual response pathways. This lack of selectivity explains why reported effects extend beyond skin darkening. Substitutions at positions four and seven, including norleucine and D-phenylalanine, increase potency and resistance to peptidases. Understanding which receptor mediates which effect remains an active area of investigation.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Alpha-MSH analogue with a lactam ring |
| Molecular formula | C50H69N15O9 | Commonly cited value for the neutral peptide |
| Molecular weight | 1024.18 g/mol | Calculated for the free molecule |
| Appearance | White to off-white powder | Typically supplied as a lyophilised solid |
| Solubility | Soluble in water, DMSO and ethanol | Dissolution in pure water is often slow |
Regulatory treatment varies between countries. Several national medicines agencies have classified the peptide as unapproved, and customs authorities in some jurisdictions seize shipments on that basis. A few jurisdictions channel supply through prescription-only frameworks that do not list the substance by name. Because the material circulates mainly through online vendors, composition and purity are rarely verified before sale. Surveys of unapproved peptide products have reported labels that did not match measured content in a substantial fraction of samples.
Melanotan II is a synthetic cyclic heptapeptide analogue of alpha-melanocyte-stimulating hormone, a naturally occurring peptide involved in pigmentation signalling. Its structure substitutes a lactam bridge between side chains to increase stability relative to the native hormone. The compound is also known by the shorthand MT-II and by several non-proprietary synonyms used in research catalogues. It is not an approved therapeutic product in any major jurisdiction; material sold under this name is typically offered as a laboratory reagent rather than as a medicine.
Activity is attributed to agonism at melanocortin receptors, particularly MC1R and MC4R. Activation of MC1R on melanocytes increases melanin synthesis, which underlies the reported tanning effect. MC4R engagement in the central nervous system is linked to appetite suppression and to effects on sexual arousal reported in early clinical studies. Those studies were small and were not designed to establish efficacy or long-term safety. Receptor selectivity among the melanocortin subtypes is not absolute, which complicates attribution of any effect to a single pathway.
==== Hypothetical origin ==== The top half of tRNA (consisting of the T arm and the acceptor stem with 5′-terminal phosphate group and 3′-terminal CCA group) and the bottom half (consisting of the D arm and the anticodon arm) are independent units in structure as well as in function. The top half may have evolved first including the 3′-terminal genomic tag which originally may have marked tRNA-like molecules for replication in early RNA world. The bottom half may have evolved later as an expansion, e.g. as protein synthesis started in RNA world and turned it into a ribonucleoprotein world (RNP world). This proposed scenario is called genomic tag hypothesis. In fact, tRNA and tRNA-like aggregates have an important catalytic influence (i.e., as ribozymes) on replication still today. These roles may be regarded as 'molecular (or chemical) fossils' of RNA world. In March 2021, researchers reported evidence suggesting that an early form of transfer RNA could have been a replicator ribozyme molecule in the very early development of life, or abiogenesis. Evolution of type I and type II tRNAs is explained to the last nucleotide by the three 31 nucleotide minihelix tRNA evolution theorem, which also describes the pre-life to life transition on Earth. Three 31 nucleotide minihelices of known sequence were ligated in pre-life to generate a 93 nucleotide tRNA precursor.
In 1963, Sanders and Deborah Shiling Messing, whom he met in college, volunteered for several months on the Israeli kibbutz Sha'ar HaAmakim. They married in 1964 and bought a summer home in Vermont; they had no children and divorced in 1966. His son (and only biological child), Levi Sanders, was born in 1969 to then-girlfriend Susan Campbell Mott. On May 28, 1988, Sanders married Jane O'Meara Driscoll (née Mary Jane O'Meara), who later became president of Burlington College, in Burlington, Vermont. The day after their wedding, the couple visited the Soviet Union as part of an official delegation in his capacity as mayor. They own a row house in Capitol Hill, a house in Burlington's New North End neighborhood, and a lakefront summer home in North Hero. He considers Jane's three children—Dave Driscoll (born 1975), Carina Driscoll (born 1974), and Heather Titus (née Driscoll; 1971)—to be his own. Sanders's elder brother, Larry, lives in England; he was a Green Party county councillor, representing the East Oxford division on Oxfordshire County Council, until he retired from the council in 2013. Larry ran as a Green Party candidate for Oxford West and Abingdon in the 2015 British general election and came in fifth. Bernie Sanders told CNN, "I owe my brother an enormous amount. It was my brother who actually introduced me to a lot of my ideas."
== Reactions == Ammonium sulfate decomposes upon heating above 250 °C (482 °F), first forming ammonium bisulfate. Heating at higher temperatures results in decomposition into ammonia, nitrogen, sulfur dioxide, and water. As a salt of a strong acid (H2SO4) and weak base (NH3), its solution is acidic; the pH of 0.1 M solution is 5.5. In aqueous solution the reactions are those of [NH4]+ and SO2−4 ions. For example, addition of barium chloride, precipitates out barium sulfate. The filtrate on evaporation yields ammonium chloride (NH4Cl). Ammonium sulfate forms many double salts (ammonium metal sulfates) when its solution is mixed with equimolar solutions of metal sulfates and the solution is slowly evaporated. With trivalent metal ions, alums such as ferric ammonium sulfate (NH4Fe(SO4)2·12H2O) are formed. Double metal sulfates include ammonium cobaltous sulfate, ferrous diammonium sulfate ((NH4)2SO4·Fe(SO4)·6H2O), ammonium nickel sulfate which are known as Tutton's salts (M2M′(SO4)2(H2O)6) and ammonium ceric sulfate ((NH4)4Ce(SO4)4·2H2O). Anhydrous double sulfates of ammonium also occur in the Langbeinites family. Airborne particles of evaporated ammonium sulfate comprise approximately 30% of fine particulate pollution worldwide. It reacts with additional sulfuric acid to give triammonium hydrogen disulphate, (NH4)3H(SO4)2.
This hypothesis posits that the physiological processes of mitochondrial stress induction (affecting neuronal plasticity) and vasodilation, which cooperatively increase microvascular blood flow and tissue oxygenation, are the basis of the natural neurostimulation. It is also thought to be a foundation of many non-invasive artificial neuromodulation techniques. Because if the mother-fetus interactions allow the child's nervous system to grow with adequate biological sentience, similar (while scaling) environmental interactions can heal the damaged nervous system in adults.
Sources: en.wikipedia.org
Diaphoresis is a non-specific symptom or sign, which means that it has many possible causes. Some causes of diaphoresis include physical exertion, menopause, fever, ingestion of toxins or irritants, and high environmental temperature. Strong emotions (anger, fear, anxiety) and recall of past trauma can also trigger sweating. This is sometimes referred to as flop sweat. The vast majority of sweat glands in the body are innervated by sympathetic cholinergic neurons. Sympathetic postganglionic neurons typically secrete norepinephrine and are named sympathetic adrenergic neurons; however, the sympathetic postganglionic neurons that innervate sweat glands secrete acetylcholine and hence are termed sympathetic cholinergic neurons. Sweat glands, piloerector muscles, and some blood vessels are innervated by sympathetic cholinergic neurons.
==== Neutrophil extracellular traps ==== In 2004, Brinkmann and colleagues described a striking observation that activation of neutrophils causes the release of web-like structures of DNA; this represents a third mechanism for killing bacteria. These neutrophil extracellular traps (NETs) comprise a web of fibers composed of chromatin and serine proteases that trap and kill extracellular microbes; thus, by forming NETs (NETosis), neutrophils can bind, disarm, and kill microbes independent of phagocytic uptake. These functions are achieved through the release of highly concentrated antimicrobial components including proteins from granules and powerful histone proteins from the nucleus. In addition to their possible antimicrobial properties, NETs may serve as a physical barrier that prevents further spread of pathogens. Trapping of bacteria may be a particularly important role for NETs in sepsis, where NETs are formed within blood vessels. Finally, NET formation has been demonstrated to augment macrophage bactericidal activity during infection. Recently, NETs have been shown to play a role in inflammatory diseases, as NETs could be detected in preeclampsia, a pregnancy-related inflammatory disorder in which neutrophils are known to be activated. Neutrophil NET formation may also impact cardiovascular disease, as NETs may influence thrombus formation in coronary arteries. NETs are now known to exhibit pro-thrombotic effects both in vitro and in vivo. More recently, in 2020 NETs were implicated in the formation of blood clots in cases of severe COVID-19.
== Structure == Fibrous bands anchoring the skin to the deep fascia Collagen and elastin fibers attaching it to the dermis Fat is absent from the eyelids, clitoris, penis, much of pinna, and scrotum Blood vessels on route to the dermis Lymphatic vessels on route from the dermis The glandular part of some sweat glands; mammary glands lie entirely within the subcutaneous tissue (which are modified apocrine sweat glands) Cutaneous nerves and free endings Hair follicle roots Ruffini and Pacinian corpuscles Mast cells Bursae, in the space overlying joints in order to facilitate smooth passage of overlying skin Fine, flat sheets of muscle, in certain locations, including the scalp, face, hand, nipple, and scrotum, called the panniculus carnosus The hypodermis forms an important insulating layer and/or food store in some animals, such as whales and hibernating mammals. In some plants, the hypodermis is a layer of cells immediately below the epidermis of leaves. It is often mechanically strengthened, for example, in pine leaves, forming an extra protective layer or a water storage tissue.
On July 1, 2026, it was reported that Markwayne Mullin, the Secretary of Homeland Security at that time, held an investment "worth as much as $1 million in Botanic Tonics, which could benefit from the new restrictions by facing less competition in the kratom market".
== Spectroscopy == Both the fluorescence excitation and emission spectrums of wild-type EosFP are shifted ~65 nm to the right upon excitation toward the red end of the spectrum. This spectral change is caused by an extension of the chromophore accompanied by a break in the peptide backbone between Phe-61 and His-62 in an irreversible mechanism. The presence of a crisp isosbestic point at 432 nm also suggests an interconversion between two species. An absorption peak at 280 nm is visible due to aromatic amino acids which transfer their excitation energy to the green chromophore. The quantum yield of the green-emitting form of Eos is 0.7. In the red shifted species, there are pronounced vibronic sidebands separate from the main peak at 533 nm and 629 nm in the excitation spectrum and emission spectrum respectively. There is another peak in the red excitation spectrum at 502 nm likely due to FRET excitation of the red fluorophore. The quantum yield of the red-emitting form is 0.55. EosFPs variants show almost no difference in spectroscopic properties, therefore, it is likely that the structural modifications which arise from separation of interfaces have little to no effect on the structure of the fluorophore-binding site.
Sources: en.wikipedia.org
== Common themes == Architect Richard Buday has contended that architectural works have been used to justify loyalty to an area's rulers, or to religious and spiritual figures. Buday suggests that "the Sphinx and the pyramids were outsized visual demands for respect and obedience to Pharaoh. The Parthenon was constructed for societal manipulation, as well as to honor a goddess (the temple's ornamentation reminded Athenians that their beating back of a Persian invasion was an act of divine intervention). Roman triumphal arches were self-aggrandizing demonstrations of rulers' might and superiority". Later in history, Buday writes that various leaders have invoked particular architectural styles to invoke connections with previous historical states and ideas which are associated with them, such as using ancient Greek and Roman imagery to convey the idea of democracy, or invoking similar classical architecture to denote imperial ambitions. In modern times, architecture is used to attract tourism.
== Further reading == Genck, Wayne (7 November 2010). "Make The Most of Antisolvent Crystallization". Chemical Processing. Putman Media. Retrieved 12 June 2025. Sheehan, David (2009). Physical Biochemistry: Principles and Applications. John Wiley & Sons. p. 285. ISBN 978-0-470-85602-4. Miller, S A; Dykes, D D; Polesky, H F (11 February 1988). "A simple salting out procedure for extracting DNA from human nucleated cells". Nucleic Acids Research. 16 (3): 1215. CiteSeerX 10.1.1.941.1917. doi:10.1093/nar/16.3.1215. PMC 334765. PMID 3344216. {{cite journal}}: Cite uses deprecated parameter |citeseerx= (help) McKay, H. A. C. (1 January 1953). "Activities and activity coefficients in ternary systems". Transactions of the Faraday Society. 49: 237–242. doi:10.1039/TF9534900237.
== Diagnosis == Diagnosing hyperandrogenism can be complex due to the wide variety and severity of signs and symptoms that may present. It is most often diagnosed by checking for signs of hirsutism according to a standardized method that scores the range of excess hair growth. Girls may show symptoms of hyperandrogenism early in life, but physicians become more concerned when the patient is in her late teens or older. Checking medical history and a physical examination of symptoms are used for an initial diagnosis. Patient history assessed includes age at thelarche, adrenarche, and menarche; patterns of menstruation; obesity; reproductive history; and the start and advancement of hyperandrogenism symptoms. Patterns of menstruation are examined since irregular patterns may accompany hyperandrogenism. Other conditions that may present alongside hirsutism that can contribute to diagnosis include androgenic alopecia and acne. If hyperandrogenism is severe, virilization may occur. Family history is also assessed for occurrences of hyperandrogenism symptoms or obesity in other family members. Laboratory tests can measure FSH, luteininzing hormone, DHEAS, prolactin, 17α-hydroxyprogesterone, and total and free testosterone in the blood. Abnormally high levels of any of these hormones help in diagnosing hyperandrogenism.
In 2009, the PLA held its first military exercise in Africa, a humanitarian and medical training practice conducted in Gabon. For the past 10 to 20 years, the PLA has acquired some advanced weapons systems from Russia, including Sovremenny-class destroyers, Sukhoi Su-27 and Kilo-class diesel-electric submarines. It has also started to produce several new classes of destroyers and frigates including the Type 052D class guided-missile destroyer. In addition, the PLAAF has designed its very own Chengdu J-10 fighter aircraft and a new stealth fighter, the Chengdu J-20. The PLA launched the new Jin class nuclear submarines on 3 December 2004 capable of launching nuclear warheads that could strike targets across the Pacific Ocean and have three aircraft carriers, with the latest, the Fujian, launched in 2022. From 2014 to 2015, the PLA deployed 524 medical staff on a rotational basis to combat the Ebola virus outbreak in Liberia, Sierra Leone, Guinea, and Guinea-Bissau. As of 2023, this was the PLA's largest medical assistance mission in another country. China re-organized its military from 2015 to 2016. In 2015, the PLA formed new units including the PLA Ground Force, the PLA Rocket Force, and the PLA Strategic Support Force. In 2016, the CMC replaced the four traditional military departments with a number of new bodies. China replaced its system of seven military regions with newly established Theater Commands: Northern, Southern, Western, Eastern, and Central. In the prior system, operations were segmented by military branch and region.
== DNA repair == Hydras are capable of two types of DNA repair: nucleotide excision repair and base excision repair. The repair pathways facilitate DNA replication by removing DNA damage. Their identification in Hydra was based, in part, on the presence in its genome of genes homologous to ones present in other genetically well studied species playing key roles in these DNA repair pathways.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide modelled on alpha-melanocyte-stimulating hormone. A lactam bridge links two side chains, forming a ring that stabilises the molecule against proteolysis. It belongs to the broader melanocortin peptide family.
No national medicines agency has approved melanotan-2 for clinical use. Afamelanotide, a related but distinct peptide, holds a marketing authorisation in the European Union for a rare photosensitivity disorder. Melanotan-2 itself is handled as a laboratory chemical.
Its broad activity across melanocortin receptors makes it a tool for probing pigmentation, appetite and vascular signalling. Early trials recorded skin darkening and other effects that were not the original focus of the work. Those observations generated hypotheses that later studies have examined.
No regulator in a major market has approved it for human use. It appears in research settings and in products marketed outside pharmacy channels. Legal status for personal possession varies by country.