melanocortin receptors raises a handful of sensible questions. This page answers them in order, starting with the fundamentals and moving to applications.
Reviewed 2025-11-04. Anything still debated is marked as such rather than presented as settled.
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.
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.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Analog of alpha-melanocyte-stimulating hormone |
| Primary receptor family | Melanocortin receptors MC1R through MC5R | Binding is not subtype-selective |
| Development period | 1980s | Synthesized during pigmentation and appetite research |
| Regulatory status | Not an approved medicine | No major regulator has authorized human use |
| Related compound | Afamelanotide | Linear analog studied for photoprotection |
The peptide was developed during the 1980s by researchers investigating melanocortin signalling and skin pigmentation pathways. Early work focused on analogues of alpha-melanocyte-stimulating hormone that would resist enzymatic breakdown more effectively than the parent molecule. Melanotan-2 emerged from that programme as a shortened, cyclised variant. Reports describing its synthesis and receptor activity later appeared in the scientific literature. Commercial availability grew through unregulated channels rather than through pharmaceutical approval.
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, the naturally occurring peptide involved in pigmentation signalling. Its sequence is conventionally written as Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH2, with a lactam bridge joining the aspartate side chain to the lysine side chain. The empirical formula is C50H69N15O9 and the monoisotopic mass lies near 1023.5 daltons. N-terminal acetylation and the D-configured phenylalanine both increase resistance to enzymatic breakdown compared with the parent hormone.
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.
== Applying, wearing and using == Injection ports are usually applied by the patient. The device comes with a needle surrounded by a soft cannula. The needle and cannula are manually inserted into the patient's tissue. Immediately after insertion the needle is removed and the cannula remains below the surface of the skin. Ports are usually worn on the abdomen, but can also be worn on other areas such as the buttocks, thigh or arm. Typical injection ports are worn for 3 days and then replaced with another port. Insulin is injected via a syringe into the injection port. Medication immediately flows through the device's cannula into the subcutaneous tissue layer. No medication is stored in the device (other than the small amount of dead-space in the medication channel within the device).
== Early life and education == Sur did his early schooling at the St. Joseph's Collegiate School, Allahabad. He received a Bachelor of Technology degree in electrical engineering from the Indian Institute of Technology in Kanpur (IIT Kanpur) in 1974, and Master of Science and PhD degrees in electrical engineering in 1975 and 1978, respectively, from Vanderbilt University in Nashville. After postdoctoral research at Stony Brook University, he was appointed to the faculty of Yale University School of Medicine in 1983.
The human skin is the outer covering of the body and is the largest organ of the integumentary system. The skin has up to seven layers of ectodermal tissue guarding muscles, bones, ligaments and internal organs. Human skin is similar to most of the other mammals' skin, and it is very similar to pig skin. Though nearly all human skin is covered with hair follicles, it can appear hairless. There are two general types of skin: hairy and glabrous skin (hairless). The adjective cutaneous literally means "of the skin" (from Latin cutis, skin). Skin plays an important immunity role in protecting the body against pathogens and excessive water loss. Its other functions are insulation, temperature regulation, sensation, synthesis of vitamin D, and the protection of vitamin B folates. Severely damaged skin will try to heal by forming scar tissue. This is often discoloured and depigmented. In humans, skin pigmentation (affected by melanin) varies among populations, and skin type can range from dry to non-dry and from oily to non-oily. Such skin variety provides a rich and diverse habitat for the approximately one thousand species of bacteria from nineteen phyla which have been found on human skin.
Often in the continuation of this anaerobic exercise, the product from this metabolic mechanism builds up in what is called lactic acid fermentation. Lactate is produced more quickly than it is being removed and it serves to regenerate NAD+ cells on where it's needed. During intense exercise when oxygen is not being used, a high amount of ATP is produced and pH levels fall causing acidosis or more specifically lactic acidosis. Lactic acid build up can be treated by staying well-hydrated throughout and especially after the workout, having an efficient cool down routine and good post-workout stretching. Intense activity can cause significant and permanent damage to bodily tissues. In order to repair, vitamin E and other antioxidants are needed to protect muscle damage. Oxidation damage and muscle tissue breakdown happens during endurance running so athletes need to eat foods high in protein in order to repair these muscle tissues. It is important for female endurance runners to consume proper nutrients in their diet that will repair, fuel, and minimize fatigue and injury. To keep a female runner's body performing at its best, the ten nutrients need to be included in their diets.
E-cigarette vapor potentially contains harmful chemicals not found in tobacco smoke. E-cigarette vapor contains fewer toxic chemicals, and lower concentrations of potential toxic chemicals than cigarette smoke. The vapor is probably much less harmful to users and bystanders than cigarette smoke, although concern exists that the exhaled vapor may be inhaled by non-users, particularly indoors.
Sources: en.wikipedia.org
Under anoxic conditions, the predominant double-base lesion is a species in which C8 of guanine is linked to the 5-methyl group of an adjacent 3'-thymine (G[8,5- Me]T). Most of these oxygen-derived species are produced by normal aerobic metabolism. Normal cellular defense mechanisms destroy most of these. Repair of oxidative damages to DNA is frequent and ongoing, largely keeping up with newly induced damages. In rat urine, about 74,000 oxidative DNA adducts per cell are excreted daily. There is also a steady state level of oxidative damages in the DNA of a cell. There are about 24,000 oxidative DNA adducts per cell in young rats and 66,000 adducts per cell in old rats. Likewise, any damage to cells is constantly repaired. However, under the severe levels of oxidative stress that cause necrosis, the damage causes ATP depletion, preventing controlled apoptotic death and causing the cell to simply fall apart. Polyunsaturated fatty acids, particularly arachidonic acid and linoleic acid, are primary targets for free radical and singlet oxygen oxidations.
Years pass and Annie contacts Demon about publishing his book. Demon knows that she is expecting a baby and drives to Lee County to meet her instead. After seeing that Lewis has taken Annie to the hospital to give birth, Demon visits Betsy, Dick and June. Skipping a retirement party for Coach, Demon fears the traumatic memories that returning to Lee County would surface. He asks Betsy about Angus’ love life, knowing she shares things with Betsy she doesn’t with him. Coyly, the old woman tells him to ask her himself, saying she only has one man in mind. Visiting Angus the next day, who is preparing to sell Coach's old house, Demon begins to understand they have always had feelings for each other. The book ends with Angus and Demon driving toward the ocean together, his hand tenderly touching the back of her neck.
where Da is the symbol for the unit dalton (also called the unified atomic mass unit, symbol u), and e is the elementary charge, which is the unit of electric charge in the system of atomic units. For example, the ion C7H72+ has a mass of 91 Da. Its charge number is +2, and hence its charge is 2e. The ion will be observed at 45.5 Th in a mass spectrum. The thomson allows for negative values for negatively charged ions. For example, the benzoate anion would be observed at −121 Th since the charge is −e.
VR-1065 is a serotonin 5-HT2C receptor agonist which was under development for the treatment of obesity but was never marketed. Its pharmacology has not been described. The drug was under development by Roche and Vernalis Group. It reached phase 1 clinical trials prior to the discontinuation of its development in 2002. The drug's development was discontinued due to suboptimal pharmacokinetics in phase 1 trials. The chemical structure of VR-1065 has not been disclosed.
Sources: en.wikipedia.org
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.
Afamelanotide is a linear analog that has received approval in some jurisdictions for a specific photoprotection indication. Melanotan II is cyclic and less selective across melanocortin receptors. The two are related but are not interchangeable in regulatory or clinical terms.
A compound that activates several receptor subtypes may produce effects beyond pigmentation. Selectivity influences which tissues respond and shapes the side-effect profile described in reports. Designing subtype-selective analogs is a stated goal of melanocortin research.
No. It is a synthetic analogue carrying four amino acid changes, a lactam ring and an amidated C-terminus. The natural hormone is a linear thirteen-amino-acid peptide processed from proopiomelanocortin.