If you have been reading about cyclic heptapeptide and want a single page that covers the useful parts, this is it: definitions, context, how it is studied, and the questions that come up repeatedly.
Last reviewed on 2026-08-01. Where a claim depends on a specific study, the study is described rather than over-claimed.
Melanotan II is a synthetic cyclic heptapeptide that acts as an agonist at melanocortin receptors. It was designed as a structural analogue of alpha-melanocyte-stimulating hormone, the endogenous peptide involved in pigment production. The analogue carries a lactam bridge that constrains the ring and slows enzymatic breakdown relative to the native hormone. In research literature it appears under several abbreviations, and naming conventions are not fully standardized. Published descriptions usually place it within the broader melanocortin agonist family.
Receptor binding at MC1R on melanocytes raises intracellular cyclic AMP and increases expression of tyrosinase and related enzymes. The downstream result is greater synthesis of eumelanin, the dark pigment, without ultraviolet exposure acting as the trigger. The compound is not selective, however, and also engages MC3R, MC4R and MC5R, which are expressed in the central nervous system and elsewhere. That lack of selectivity is the explanation usually offered for effects reported outside pigmentation, including appetite suppression and nausea. Selectivity remains a central theme in comparative studies of related peptides.
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.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Synthetic cyclic heptapeptide | Melanocortin receptor agonist |
| Molecular formula | C50H69N15O9 | Neutral form, mass near 1024.2 g/mol |
| Primary targets | MC1R, MC3R, MC4R, MC5R | Binding is non-selective across subtypes |
| Related compounds | Alpha-MSH, melanotan I, afamelanotide | Structurally or functionally related peptides |
| Common abbreviations | MT-II, MT-2 | Naming in the literature is not uniform |
If feather-like structures were indeed widely present among non-avian dinosaurs, the lack of abundant fossil evidence for them may be due to the fact that delicate features like skin and feathers are seldom preserved by fossilization and thus often absent from the fossil record.
=== Allies === Wolverine is primarily presented as part of the X-Men and has had extensive interactions with all of them and their associates. Nightcrawler is one of his closest friends and was one of the first X-Men to look past Logan's demeanor, which was initially quite abrasive. Wolverine has also teamed up with Gambit on missions separate from the rest of the X-Men. In particular, Wolverine has a complex and ambivalent relationship with Cyclops, with whom he was initially a rival for the affections of Jean Grey. Logan was one of the original member of Alpha Flight, although he left the group out of frustration with their role as Canadian government operatives. He has also been a member of the Avengers, X-Force, and at times has joined the Fantastic Four. Outside his team allegiances, he has frequently allied with Elektra, particularly during periods when it becomes necessary for him to regain control of his impulses.
Measuring gene expression is an important part of many life sciences, as the ability to quantify the level at which a particular gene is expressed within a cell, tissue or organism can provide a lot of valuable information. For example, measuring gene expression can:
Sources: en.wikipedia.org
These included statements that God emits a cosmic broadcast of electromagnetic waves that living creatures can receive when their neural networks are enabled by DMT; that adding DMT allows people to see otherwise invisible spirits and guardian angels; that schizophrenia and autism result from an over-abundance of bioavailable DMT and should be unified under the term “Autiphrenia,” with those affected described as geniuses created to lead humanity; that vaporizing DMT had cured his brain cancer; that staring at the sun promotes DMT production in the pineal gland; and that DMT could cure other diseases. He invited cancer patients to his ranch in the Lake View Terrace area of Los Angeles to try the substance. In a video recorded after the cancer claim was questioned, Cantelmo stated that he had never had any form of cancer and that the reference was metaphorical, describing atheism as the “worst form of cancer.” His brother Craig and other family members confirmed he had never been diagnosed with cancer.
=== Bioelectricity === The potential use of developmental bioelectricity in regenerative medicine is under active investigation, with particular interest in future organ and limb regeneration guided by bioelectric stimulation. Developmental bioelectricity refers to endogenous ion flows and voltage gradients across cell membranes (Vmem) in excitable (able to create an action potential) and non-excitable tissues that provide instructive cues for growth. These bioelectric states, set by ion channels and pumps, are propagated through gap-junction coupling and together with chemical gradients and physical forces they form long-range patterning circuits. Through voltage-sensitive signalling pathways, changes in Vmem modulate gene expression and cell behaviours (proliferation, migration, differentiation), thereby shaping tissue growth and polarity. Experiments in vertebrate and invertebrate models indicate that bioelectric cues can steer regeneration. In Xenopus tadpoles, activating a proton pump (V-ATPase) that moves hydrogen ions out of cells is necessary for tail regrowth and can restore regeneration during a normally refractory stage; in adult Zebrafish, inhibiting the same pump impairs fin regrowth. In Planarians, brief electrical perturbations can cause tail pieces to form heads (including two-headed animals) or to regenerate heads resembling other species. In adult frogs, a 24-hour treatment with a drug-delivering ‘BioDome’ device initiated long-term hindlimb regrowth with multi-tissue repair and functional recovery.
Aminoacylases are expressed in the kidney, where they recycle N-acyl-L-amino acids as L-amino acids and aid in urea cycle regulation. N-acyl-L-amino acids are formed when L-amino acids have their N-terminus covalently bonded to an acyl group. The acyl group provides stability for the amino acid, making it more resistant to degradation. Additionally, N-acyl-L-amino acids cannot be used directly as building blocks for proteins and must first be converted to L-amino acids by aminoacylase. Again, the L-amino acid products can be used for biosynthesis or catabolized energy. Aminoacylase is involved in the regulation of the urea cycle. N-acetyl-L-glutamate is an allosteric activator of carbamoyl phosphate synthetase, a crucial enzyme that commits NH4+ molecules to the urea cycle. The urea cycle gets rid of excess ammonia (NH4+) in the body, a process that must be up-regulated during times of increased protein catabolism, as amino acid breakdown produces large amounts of NH4+. When amino acid catabolism increases, N-Acetylglutamate synthase is up-regulated, producing more N-acetyl-L-glutamate, which up-regulates carbamoyl phosphate synthetase and allows it to dispose of the excess NH4+ from catabolism. Aminoacylase is up-regulated during times of nutrient deficit or starvation, causing N-acetyl-L-glutamate breakdown, which down-regulates carbamoyl phosphate synthetase and the rest of the urea cycle.
Sources: en.wikipedia.org
It is a synthetic cyclic heptapeptide and a non-selective melanocortin receptor agonist. Structurally it is modelled on alpha-melanocyte-stimulating hormone, a peptide that occurs naturally in the body.
Activation of MC1R increases pigment synthesis independently of ultraviolet exposure, which is the mechanism usually cited for darkening without sun exposure. Ultraviolet light still influences skin response through separate biological pathways.
Because the peptide binds several melanocortin receptor subtypes, its effects are not confined to pigmentation. This complicates interpretation of both intended and unintended outcomes reported in studies.
No. No major regulatory agency has granted a marketing authorisation for melanotan II as a medicine. Products sold under this name are generally presented as laboratory reagents and are not subject to the batch-release testing applied to approved drugs.