Brain hunger-control hormone (γ3-MSH)
A natural brain and pituitary hormone that activates the brain's appetite and body-weight control circuit; used only as a lab research tool.
- Class
- Endogenous melanocortin peptide fragment
- Status
- No approved therapeutic status identified
- Main caveat
- Source file is a vendor catalog entry with sequence and storage handling notes only. No bioactivity, mechanism, safety, or clinical data are present in the compiled source.
A researcher, an agent, or an algorithm wrote down the sequence and picked a target to hit.
An AI model like OpenFold3 or AlphaFold built a 3D structure and scored how well it fits the binding site.
A second contributor repeated the computation on their own hardware and the scores matched.
A chemistry service or a researcher ordered the sequence, it was manufactured, and mass spectrometry confirmed the right molecule was produced.
A binding or activity measurement confirmed that it actually does what the computer predicted — or didn't.
What this is
γ3-MSH (gamma-3 melanocyte-stimulating hormone) is a small signaling peptide produced naturally in the human brain and pituitary gland. It is one of eight active hormones cleaved from the precursor protein pro-opiomelanocortin (POMC), a single large prohormone that the body processes into distinct peptides with distinct jobs (Yanik and colleagues 2025; Ericson and colleagues 2017). γ3-MSH is encoded in the N-terminal domain of POMC — a different region from α-MSH and β-endorphin — and acts primarily at the melanocortin-4 receptor (MC4R), a receptor expressed in brain circuits that regulate hunger, body weight, and autonomic function (Mountjoy and colleagues 1994).
The stored sequence (YVMGHFRWDRFGRRNGSSSSGVGGAAQ, 27 residues) represents a synthetic analog used in research; the naturally occurring γ3-MSH is 23 residues and carries N-linked glycosylation that is not present in the unmodified research peptide (Ericson and colleagues 2017).
What it does
γ3-MSH engages MC4R in hypothalamic and brainstem circuits that are part of the leptin–melanocortin axis, a system that helps the body sense how much energy it has stored and adjust eating behavior accordingly (Begriche and colleagues 2009; Yanik and colleagues 2025). Activation of MC4R in these circuits suppresses food intake and supports energy expenditure. MC4R is also expressed in enteroendocrine L cells of the gut, where its activation promotes the release of the satiety hormones peptide YY (PYY) and glucagon-like peptide-1 (GLP-1), adding a peripheral component to its energy-regulating role (Panaro and colleagues 2014).
Beyond energy balance, MC4R is expressed in brain areas involved in food-reward signaling, where it interacts with dopaminergic circuits (Yoon and colleagues 2015). Melanocortin agonists acting at this receptor family have also been shown to stimulate lipolysis in human adipose tissue explants, suggesting a role in fat mobilization (Møller and colleagues 2015).
Evidence
- Human: No clinical trials of γ3-MSH itself have been published. The importance of the MC4R pathway it engages is established in humans through genetic studies: loss-of-function mutations in MC4R are among the most common known causes of monogenic obesity, and POMC mutations that eliminate production of γ3-MSH and related peptides likewise lead to early-onset severe obesity (Yanik and colleagues 2025).
- Animal: MC4R expression in neuroendocrine and autonomic control circuits has been mapped in rodent brain (Mountjoy and colleagues 1994); gut MC4R activation regulating PYY and GLP-1 release was demonstrated in mouse models (Panaro and colleagues 2014).
- In vitro: Melanocortin agonists stimulate lipolysis in human adipose tissue explants but not in isolated adipocytes, suggesting the effect requires multicellular tissue context (Møller and colleagues 2015). Structure-activity studies of cyclic melanocortin peptides at MC3R, MC4R, and MC5R have informed understanding of receptor selectivity at this locus (Grieco and colleagues 2003).
Mechanism
γ3-MSH is a melanocortin receptor agonist. MC4R is a Gαs-coupled receptor: binding triggers adenylyl cyclase activation and cAMP elevation in target neurons. Within the hypothalamic melanocortin system, MC4R-expressing neurons sit downstream of leptin signaling from adipose tissue — leptin promotes POMC processing (releasing γ3-MSH and related peptides) and suppresses AgRP/NPY neurons that oppose MC4R activation. This circuit constitutes the central homeostatic governor of energy balance (Begriche and colleagues 2009; Yanik and colleagues 2025).
MC4R is also expressed in autonomic circuits projecting to peripheral organs, enabling melanocortin-mediated control of heart rate, blood pressure, and metabolic rate (Mountjoy and colleagues 1994). The enteroendocrine arm — MC4R on gut L cells driving PYY and GLP-1 secretion — provides a peripheral brake on food intake that parallels the central signal (Panaro and colleagues 2014).
The N-terminal γ-MSH series (γ1, γ2, γ3) shares structural ancestry and some pharmacological overlap with α-MSH, but the γ-MSH peptides arise from a different POMC cleavage site and have somewhat different receptor profiles. γ3-MSH can be further processed to γ2-MSH (its N-terminal 12 amino acids) and γ1-MSH (N-terminal 11 amino acids) by tissue-specific proteases (Ericson and colleagues 2017).
Related peptides
- α-MSH — the best-studied POMC-derived melanocortin peptide, acting at MC1R (pigmentation) and MC4R (energy balance); shares the core His-Phe-Arg-Trp pharmacophore with γ3-MSH.
- Setmelanotide — a synthetic MC4R agonist approved for treatment of genetic obesity caused by POMC, PCSK1, or LEPR mutations; the clinical validation of the pathway that γ3-MSH engages.
- γ1-MSH / γ2-MSH — shorter cleavage products of γ3-MSH arising from the same N-terminal POMC domain, generated by tissue-specific proteases (Ericson and colleagues 2017).
Research directions for this peptide, selected from the current sources — hypotheses you can explore and model. None of it is proven yet; tap any one to see the full thinking.
Does removing a sugar-chain modification that the natural hormone carries make this peptide bind the hunger receptor more tightly and work better?
If the synthetic, sugar-free form of this peptide is more potent than the natural version, it gives drug developers a more effective starting material for obesity or cachexia treatments. Understanding that the sugar acts as a natural brake on this peptide's activity also reveals a biological control mechanism that researchers may be able to exploit.
Is most of this peptide's hunger-reducing effect actually produced by just the central 8 amino acids, with the rest being unnecessary?
If only a short segment of the peptide is doing the work, a much smaller drug could be made that is easier to produce, more stable, and potentially more potent. Smaller peptide drugs are also generally cheaper and sometimes easier to take, which matters for long-term obesity treatment.
Does the extra stretch of amino acids beyond the active core of this peptide help it bind specifically to the appetite-controlling receptor rather than the heart-affecting one?
Drugs that activate appetite receptors sometimes also affect the heart and immune system because related receptors are involved. If this peptide naturally avoids those related receptors because of its unique shape, it could be a safer starting point for developing an obesity treatment with a lower risk of cardiovascular side effects.
Does this brain-classified peptide actually reduce appetite mostly by acting on the gut to release hunger-suppressing hormones, rather than acting directly on brain circuits?
Many obesity drugs targeting the brain cause side effects like nausea, anxiety, or cognitive effects. If the appetite-reducing action of this peptide mainly happens in the gut, it may be possible to develop a version that stays in the gut and avoids brain-related side effects, making it safer for long-term use.
Could this peptide help cancer patients keep weight and muscle by simultaneously making them want to eat and reducing the inflammation that destroys muscle?
Cancer cachexia, the extreme muscle and weight loss that kills roughly one in five cancer patients, has no approved drug treatment. A single therapy that both restores appetite and blocks the inflammatory signals that destroy muscle could potentially extend and improve the lives of hundreds of thousands of cancer patients each year.
▸full evidence table2 metrics
| metric | value | tool |
|---|---|---|
| ipTM | 0.8337030410766602 | boltz-2 |
| ranking score | 0.7765669822692871 | boltz-2 |
▸structural qualityopenfold3
| metric | value | note |
|---|---|---|
| gpde | 0.648 | global PDE — lower = better |
| disorder | NaN | fraction disordered |
▸3-letter notation
▸recipeboltz-2 1.0
| parameter | value |
|---|---|
| model | boltz-2 1.0 |
| weights | — |
| hardware | nvidia_nim_api |
| mlx version | — |
| python | — |
| random seed | — |
| msa strategy | none |
| diffusion samples | 1 |
| runtime | — |
| predicted by | mlx@peptide |
| predicted at | 2026-04-24 |
▸citationbibtex
@peptide{pep10723,
sequence = {YVMGHFRWDRFGRRNGSSSSGVGGAAQ},
target = {mc4r},
author = {peptidemodel},
year = {2026},
status = {computed}
}