Alpha-MSH
The prototype endogenous melanocortin peptide that governs pigmentation, inflammation, appetite, and thermoregulation through the MC1R–MC5R receptor family.
Alpha-MSH is an endogenous 13-amino-acid neuropeptide produced by proteolytic processing of proopiomelanocortin (POMC) that signals through the five melanocortin receptors (MC1R–MC5R). It regulates skin pigmentation, anti-inflammatory signaling, energy homeostasis, and thermoregulation, and serves as the structural template for the entire family of synthetic melanocortin analogues, including Melanotan I/II, PT-141/bremelanotide, and setmelanotide. Alpha-MSH itself has no FDA approval and no established human clinical trials for exogenous administration; it remains a research compound.
Class
Endogenous 13-amino-acid melanocortin neuropeptide (POMC-derived)
Half-life
~3–5 minutes (plasma)
Routes
Subcutaneous, Intranasal
Category
Sexual Health & Melanocortin
Researched benefits
What it's studied for
Anti-inflammatory signaling
Alpha-MSH suppresses NF-κB activation and reduces pro-inflammatory cytokines such as IL-1β and TNF-α, acting through MC1R and MC3R in both peripheral tissues and the central nervous system. Evidence is drawn from in vivo and in vitro preclinical models.
Immunomodulation and tolerance
Through MC1R binding, alpha-MSH and its tripeptide fragment KPV downregulate costimulatory molecules on antigen-presenting cells and can induce antigen-specific tolerance in mouse models, positioning it as a candidate immunomodulatory agent for allergic and autoimmune conditions.
Appetite and energy homeostasis
Alpha-MSH acts as an endogenous satiety signal via MC4R in the hypothalamus, opposing the appetitive effects of AgRP. The alpha-MSH/MC4R pathway is a validated obesity target — MC4R loss-of-function mutations are the most common monogenic cause of severe early-onset obesity.
Skin pigmentation
Alpha-MSH stimulates melanogenesis through MC1R, driving tyrosinase activity and expression of melanogenic proteins (MITF, TRP-2) via the PKA/cAMP/CREB pathway. It is the standard stimulus used in melanocyte and zebrafish depigmentation research.
Thermoregulation
As a central melanocortin ligand, alpha-MSH contributes to thermoregulatory control, one of its recognized endogenous physiological roles.
Mechanism
How it works
Alpha-MSH is generated by proteolytic cleavage of proopiomelanocortin (POMC) and is the prototype endogenous ligand for the melanocortin receptor family — five G-protein-coupled receptors (MC1R–MC5R) with distinct tissue distributions. Receptor activation broadly raises intracellular cAMP, and the downstream effect depends on which receptor and tissue is engaged.
Its anti-inflammatory activity is mediated principally through MC1R and MC3R. Receptor engagement inhibits NF-κB-dependent transcription in immune cells, lowering production of pro-inflammatory mediators including IL-1β and TNF-α, and modulates leukocyte activity in both peripheral and central compartments. Alpha-MSH can also activate descending anti-inflammatory neural pathways.
In energy homeostasis, alpha-MSH activates MC4R in the hypothalamus to act as a satiety signal that opposes the orexigenic peptide AgRP. In the skin, MC1R activation drives melanogenesis via the PKA/cAMP/CREB axis, increasing tyrosinase activity and MITF/TRP-2 expression.
The His-Phe-Arg-Trp pharmacophore (residues 6–9) shared by all active melanocortin analogues is derived from alpha-MSH, making it the structural reference point for synthetic descendants such as afamelanotide (Melanotan I / Scenesse), Melanotan II, bremelanotide (PT-141 / Vyleesi), and setmelanotide (Imcivree).
Evidence
Research & clinical studies (10)
Hypothalamic orexigenic and anorexigenic neuropeptides in the rotenone model of Parkinson's disease
Rotenone-induced Parkinson's disease in rats reduced expression of appetite-regulating neuropeptides including alpha-MSH without hypothalamic neuron loss, and standard therapy failed to restore these changes.
PMID 42082689Depigmenting Effects of Vitex rotundifolia Cone Essential Oil in Melanocytes and Its Chemical Composition
Vitex rotundifolia essential oil suppressed melanin synthesis in alpha-MSH-stimulated melanocytes by inhibiting tyrosinase and reducing MITF, tyrosinase, and TRP-2 via p38 MAPK and ERK1/2 signaling.
PMID 42081606Baeckea frutescens Suppresses Melanogenesis via Modulation of PKA/CREB and ERK/MAPK Pathways: Insights from Cellular, Zebrafish, and In Silico Analyses
Baeckea frutescens extract suppressed melanin production in alpha-MSH-stimulated cells by reducing tyrosinase activity and downregulating melanogenic proteins through PKA/CREB and ERK/MAPK modulation, with effects confirmed in zebrafish embryos.
PMID 42197239Antrodia cinnamomea extract exhibits anti-melanogenic and anti-photoaging effects: potential for cosmetic and dermatological applications
Antrodia cinnamomea extract suppressed melanin production and tyrosinase activity in alpha-MSH-stimulated melanocytes via the PKA/cAMP/CREB pathway and protected fibroblasts against UV-induced photoaging.
PMID 42209583Preclinical assessment of (177)Lu-DOTA-Pip-Nle-CycMSH(hex): In vivo evaluation and human dosimetry estimation
A radiolabeled alpha-MSH analogue showed high MC1R affinity, selective melanoma tumor targeting, and favorable dosimetry, supporting its potential for melanoma-targeted radionuclide therapy.
PMID 42097084Cyperenoic acid from Gentiana kurroo suppresses Melanogenesis via modulation of MITF without altering ERK and CREB phosphorylation, with predicted interaction at the MITF kink pocket
Cyperenoic acid suppressed melanogenesis by modulating MITF without altering ERK or CREB phosphorylation, with predicted binding at the MITF kink pocket.
PMID 42373055Skin-Protective Activities of Dioscorea batatas Decne Peel Extracts with Differential Phenanthrene Contents
Dioscorea batatas peel extracts demonstrated skin-protective activity related to phenanthrene content in melanogenesis-relevant assays.
PMID 42352039Melanophore physiology and adrenergic receptor signaling in zebrafish (Danio rerio)
Reviews melanophore physiology and adrenergic receptor signaling in zebrafish, a model relevant to melanocortin-driven pigmentation.
PMID 42348004New insights into the functions of alpha-MSH and related peptides in the immune system
Describes how alpha-MSH and its fragment KPV suppress inflammatory cytokine production, downregulate costimulatory molecules on antigen-presenting cells via MC1R, and induce antigen-specific tolerance in mouse models.
PMID 12851308Mechanisms of antiinflammatory action of alpha-MSH peptides. In vivo and in vitro evidence
Summarizes in vivo and in vitro evidence that alpha-MSH modulates inflammation via NF-κB inhibition, reduced pro-inflammatory cytokine production, and activation of descending anti-inflammatory neural pathways.
PMID 10816650Safety
Side effects & considerations
Contraindications & cautions
- History of melanoma
- Uncontrolled hypertension
Alpha-MSH carries a moderate risk profile in research contexts. Because it stimulates melanocyte activity, a history of melanoma is a key contraindication, and melanocortin activity may affect blood pressure, making uncontrolled hypertension a concern. No human safety data from clinical trials are available.
FAQ
Alpha-MSH — common questions
What is Alpha-MSH?
Alpha-MSH (α-melanocyte-stimulating hormone) is an endogenous 13-amino-acid peptide derived from proopiomelanocortin (POMC) that acts through the melanocortin receptors MC1R–MC5R. Its biological roles include skin pigmentation, anti-inflammatory signaling, thermoregulation, and energy homeostasis.
What is Alpha-MSH primarily studied for?
Its main research areas are anti-inflammatory activity, appetite suppression, thermoregulation, and skin pigmentation.
How does Alpha-MSH relate to peptides like Melanotan and PT-141?
Alpha-MSH is the structural template for the melanocortin analogue family. The His-Phe-Arg-Trp pharmacophore (residues 6–9) shared by Melanotan I (afamelanotide), Melanotan II, bremelanotide (PT-141), and setmelanotide is derived directly from alpha-MSH.
Is Alpha-MSH FDA approved?
No. Alpha-MSH is an endogenous neuropeptide with no FDA-approved drug product and no evaluation for any indication. It is not on the FDA 503A bulks list and is research use only. Bremelanotide (Vyleesi) is an approved derivative but a distinct compound.
What are the reported side effects and contraindications?
Reported contraindications include a history of melanoma and uncontrolled hypertension. Alpha-MSH has a moderate risk profile, and no human clinical trials have established its safety or efficacy when administered exogenously.
How is Alpha-MSH connected to obesity research?
Alpha-MSH acts as a satiety signal through MC4R in the hypothalamus. MC4R loss-of-function mutations are the most common monogenic cause of severe early-onset obesity, and setmelanotide (Imcivree), an MC4R agonist descended from the alpha-MSH mechanism, is FDA-approved for certain MC4R-pathway obesity disorders.
