Melanotan 2 Peptide

Melanotan 2 is a synthetic peptide designed as an analogue of alpha-melanocyte-stimulating hormone (α-MSH).(1) It is classified as a cyclic heptapeptide and has been structurally modified to alter its affinity for the receptors typically targeted by the endogenous hormone.

In addition to its proposed role in stimulating melanogenesis—the production of melanin pigment in skin cells—Melanotan 2 is also suggested to interact with other receptor systems involved in appetite regulation and various forms of physiological arousal.(2)

Overview

Melanotan 2 is proposed to function as a non-selective agonist, with the potential to bind to four of the five known subtypes of melanocortin receptors (MC-R).(3) The effects of this interaction may vary depending on the specific receptor subtype and its location within the body.

The four primary receptors that Melanotan 2 is suggested to interact with include:

  • The melanocortin 1 receptor (MC1R) may be expressed in melanocytes, which are cells found in tissues such as dermal tissues, hair, and possibly cells and tissues found in the eye.

  • The melanocortin 3 receptor (MC3R) might be found in a range of tissues, potentially including the brain and the placenta. Initial observations suggest that MC3R might be involved in modulating appetite under certain experimental conditions.

  • The melanocortin 4 receptor (MC4R) may be localized within the central nervous system, perhaps in the hypothalamus. Some early indications suggest that this receptor may impact neurons that are believed to have some influence over mating behaviors and general arousal.

  • The melanocortin 5 receptor (MC5R) appears to be distributed across multiple tissues, although what role it might serve remains unclear.

For example, the interaction of Melanotan 2 with melanocortin-1 receptors (MC1R) is suggested to promote the production of eumelanin, the pigment responsible for darker skin tone, thereby contributing to increased pigmentation in the epidermal layer.(4)

In contrast, binding of Melanotan 2 to melanocortin-4 receptors (MC4R) may influence supraspinal centres within the brain, which are associated with the regulation of libido. These neural signals may then be transmitted through both the sympathetic and parasympathetic pathways, including regions of the spinal cord and thoracolumbar system, potentially contributing to increased sexual arousal.(3)

Chemical Makeup

  • Other Known Titles: MT-II, Melanotan-II, [Nle4, D-Phe7]-MSH.

  • Molecular Weight: 1024.2 g/mol.

  • Molecular Formula: C50 H69 N15 O9

Research and Clinical Studies
Melanotan 2 Peptide and Nerve Cell Regeneration

Research(5) using murine models with experimentally induced peripheral nerve injury has been conducted to explore the potential neurotrophic effects of Melanotan 2. In this study, half of the models were administered the peptide, and within 48 hours, those treated with Melanotan 2 appeared to demonstrate signs of improved sensory function. Additionally, when the models were exposed to a chemotherapeutic agent, the peptide was associated with a degree of neuroprotection, suggesting it may help mitigate nerve damage caused by treatment-induced neurotoxicity. These effects are thought to be mediated, at least in part, through melanocortin-4 receptor (MC4R) activity, which may support neurite outgrowth and enhance the intrinsic regenerative capacity of neuronal tissue.

Although the precise signalling pathways remain unclear, it has been proposed that pro-opiomelanocortin (POMC)-derived melanocortin peptides—such as analogues of alpha-melanocyte-stimulating hormone (α-MSH)—may influence neuronal structure by increasing both the number and length of neurites, as well as promoting nerve sprouting in damaged regions. As a potent melanocortin receptor agonist, Melanotan 2 may initiate intracellular signalling cascades that contribute to improved nerve regeneration and partial protection against neuropathic damage. Researchers concluded that Melanotan 2 exhibited neuroprotective properties, noting that it appeared to partially protect nerve tissue from cisplatin-induced toxic neuropathy.

Melanotan 2 Peptide and Arousal Neurosignaling

In a clinical study,(6) Melanotan 2 was suggested to increase arousal-related neural signalling in more than 80% of cases, compared to approximately 20% observed in the placebo group. These findings indicate a potential central nervous system effect associated with the peptide.

The proposed mechanism involves interaction with melanocortin-4 receptors (MC4R), with downstream influence on established neuromodulatory systems, including dopaminergic and oxytocinergic pathways. These interactions may occur within specific hypothalamic regions that are responsible for coordinating homeostatic functions and motivational behaviours. Through this activity, Melanotan 2 may alter the balance of neuronal signalling within these centres.

Additionally, researchers have suggested that melanocortin-5 receptors (MC5R), which are present in certain peripheral glands, may provide a complementary pathway linking central neural activity with peripheral physiological responses. However, the exact mechanisms underlying these effects remain theoretical and require further investigation.

Melanotan 2 Peptide and Neurodevelopmental Modulation

Researchers have suggested that Melanotan 2 may influence altered neural processes by potentially stimulating neuronal populations involved in social cognition through endogenous oxytocinergic signalling.(7) These melanocortin-4 receptor (MC4R)-sensitive pathways, possibly located in regions such as the paraventricular nucleus of the hypothalamus, may promote the release of endogenous oxytocin in response to the peptide. This release could contribute to rebalancing neurochemical activity that is thought to be involved in aspects of social behaviour and interaction.

The increase in oxytocin may also influence multiple neurotransmitter systems, including serotonin, glutamate, dopamine, and GABA, all of which play important roles in regulating mood, behaviour, and social adaptation. Through these interactions, Melanotan 2 may affect the functional connectivity between cortical and subcortical brain regions—such as the anterior cingulate cortex—where variations in oxytocin receptor distribution have been observed in certain neurodevelopmental conditions.

By engaging these neural systems, researchers have hypothesised that Melanotan 2 may contribute to changes in synaptic communication and plasticity. These effects could potentially influence the organisation and function of neural networks, suggesting a possible role in modulating underlying neurobiological architecture, although these mechanisms remain theoretical and require further investigation.

Melanotan 2 Peptide and Models of Sunless Tanning

Melanotan 2 has been suggested to increase melanin production, potentially leading to darker skin pigmentation without the need for ultraviolet exposure, through its interaction with melanocortin-1 receptors (MC1R) on melanocytes.(8) Its cyclic peptide structure is also thought to support more prolonged receptor activity compared to other melanocyte-stimulating hormone (MSH) analogues.

Although the exact intracellular signalling pathways are not fully defined, current research indicates that receptor activation may enhance the synthesis of eumelanin, the pigment responsible for darker skin tones. This mechanism has been proposed as a potential basis for developing sunless pigmentation models within controlled research environments. Experimental observations have included reports of increased pigmentation in areas such as the face, upper body, and buttocks in study models, supporting the peptide’s apparent role in modulating skin pigmentation.(8)

Melanotan 2 peptide is available for research and laboratory purposes only. Please speak to our friendly research team to find out more and for sourcing options.

References:

  1. Ryakhovsky, Vladimir V et al. “The first preparative solution phase synthesis of Melanotan II.” Beilstein Journal of Organic Chemistry vol. 4 (2008): 39. doi:10.3762/bjoc.4.39.   https://pubmed.ncbi.nlm.nih.gov/19043625/

  2. Mac E. Hadley, Discovery that a melanocortin regulates sexual functions in male and female humans, Peptides, Volume 26, Issue 10, 2005, Pages 1687-1689, ISSN 0196-9781,   https://doi.org/10.1016/j.peptides.2005.01.023

  3. King, Stephen H et al. “Melanocortin receptors, melanotropic peptides and penile erection.” Current topics in medicinal chemistry vol. 7,11 (2007): 1098-1106.    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2694735/

  4. Peters, Björn, et al. “Melanotan II: a possible cause of renal infarction: review of the literature and case report.” CEN case reports vol. 9,2 (2020): 159-161. doi:10.1007/s13730-020-00447-z.     https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7148395/

  5. Ter Laak, Mariël P, et al. “The potent melanocortin receptor agonist melanotan-II promotes peripheral nerve regeneration and has neuroprotective properties in the rat.” European Journal of Pharmacology vol. 462,1-3 (2003): 179-83. doi:10.1016/s0014-2999(02)02945-x.      https://pubmed.ncbi.nlm.nih.gov/12591111/

  6. Wessells, H et al. “Melanocortin receptor agonists, penile erection, and sexual motivation: human studies with Melanotan II.” International journal of impotence research vol. 12 Suppl 4 (2000): S74-9. doi:10.1038/sj.ijir.3900582.    https://pubmed.ncbi.nlm.nih.gov/11035391/

  7. Minakova E, Lang J, Medel-Matus JS, Gould GG, Reynolds A, Shin D, Mazarati A, Sankar R. Melanotan-II reverses autistic features in a maternal immune activation mouse model of autism. PLoS One. 2019 Jan 10;14(1):e0210389. Doi: 10.1371/journal.pone.0210389. PMID: 30629642; PMCID: PMC6328175.

  8. Dorr RT, Lines R, Levine N, Brooks C, Xiang L, Hruby VJ, Hadley ME. Evaluation of melanotan-II, a superpotent cyclic melanotropic peptide in a pilot phase-I clinical study. Life Sci. 1996;58(20):1777-84. doi: 10.1016/0024-3205(96)00160-9. PMID: 8637402.

Dr. Marinov

Dr. Marinov (MD, Ph.D.) is a researcher and chief assistant professor in Preventative Medicine & Public Health. Prior to his professorship, Dr. Marinov practiced preventative, evidence-based medicine with an emphasis on Nutrition and Dietetics. He is widely published in international peer-reviewed scientific journals and specializes in peptide therapy research.

Melanotan 2 Peptide