Melanotan II (MT-2): A Melanocortin Receptor Agonist in Pigmentation and Sexual Function Research
Research Use Only. This article is for scientific and educational reference only. All products are sold for research purposes and are not intended for human or animal consumption.
Overview
Melanotan II (CAS 121062-08-6), also known as MT-2, is a synthetic cyclic heptapeptide with the sequence Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ and a molecular weight of approximately 1,024 Da. It was developed at the University of Arizona as a synthetic analogue of alpha-melanocyte-stimulating hormone (α-MSH), modified to increase potency and metabolic stability compared to the native peptide.
MT-2 is a non-selective agonist at melanocortin receptors, with activity at MC1R (skin pigmentation), MC3R (energy homeostasis), MC4R (sexual function, appetite, energy expenditure), and MC5R (exocrine gland function). This broad receptor profile has made it a valuable research tool for investigating the melanocortin system and its diverse physiological roles.
Mechanism of Action
The melanocortin system consists of five receptor subtypes (MC1R–MC5R) that are activated by endogenous melanocortin peptides derived from the proopiomelanocortin (POMC) precursor, including α-MSH, β-MSH, and ACTH. These receptors are coupled to Gs proteins and signal primarily through adenylyl cyclase activation and cAMP production.
MC1R activation by MT-2 stimulates melanogenesis in melanocytes, increasing the production of eumelanin (brown/black pigment) over pheomelanin (red/yellow pigment). This shift in melanin type and quantity results in increased skin and hair pigmentation.
MC4R activation in the hypothalamus reduces appetite and increases energy expenditure, contributing to the weight loss effects observed in MT-2 research. MC4R activation in the spinal cord and brain regions involved in sexual function mediates the pro-erectile and pro-sexual effects that have been studied in both male and female models.
MC3R activation contributes to energy homeostasis and anti-inflammatory effects, with research suggesting roles in modulating the inflammatory response to injury and infection.
Key Research Findings
Research at the University of Arizona demonstrated that MT-2 produced dose-dependent increases in skin pigmentation in human volunteers following subcutaneous administration, with effects persisting for weeks after cessation of administration. The pigmentation response was attributed to MC1R-mediated stimulation of melanogenesis.
Studies investigating MT-2's effects on sexual function demonstrated that the peptide produced penile erections in male volunteers with erectile dysfunction in a Phase 2 clinical trial, leading to the development of bremelanotide (PT-141) — a related melanocortin receptor agonist approved for hypoactive sexual desire disorder in women.
Research in animal models has explored MT-2's effects on appetite (MC3R/MC4R-mediated reduction in food intake), inflammation (MC3R-mediated anti-inflammatory effects), and neuroprotection (melanocortin receptor-mediated protection from ischemic injury).
Chemical Properties
| Property | Value | |---|---| | Sequence | Ac-Nle-cyclo[Asp-His-D-Phe-Arg-Trp-Lys]-NH₂ | | Molecular Weight | ~1,024 Da | | CAS Number | 121062-08-6 | | Receptor Targets | MC1R, MC3R, MC4R, MC5R | | Form | Lyophilized powder | | Purity (research grade) | ≥99% HPLC | | Storage | −20°C, protect from light |
Research Considerations
MT-2 is supplied as a lyophilized powder requiring reconstitution with bacteriostatic water. Its broad melanocortin receptor activity means that research protocols should account for potential effects on multiple physiological systems simultaneously. The peptide's potency at MC4R means that appetite and energy expenditure effects may be relevant variables in body composition studies.
Research Use Only. This article is for scientific and educational reference. All products are sold for research purposes only and are not intended for human or animal consumption.