Neuropeptide W (NPW)
An endogenous brain and gut peptide that suppresses feeding and tunes the stress axis, acting at the receptors GPR7 and GPR8. A research peptide, not a drug
Neuropeptide W (NPW) is an endogenous peptide of the brain and gut, named for a tryptophan (W) at each end of the molecule. It comes in two forms — a 23-amino-acid version (NPW23) and a 30-amino-acid version (NPW30) — and is one of the two natural ligands, together with neuropeptide B (NPB), of a pair of receptors called NPBWR1 (originally GPR7) and NPBWR2 (originally GPR8). Through them NPW acts as a brake on food intake and an endogenous catabolic signal, raising heat production and body temperature, while its receptors sit in the stress- and emotion-handling parts of the brain. It also tunes neuroendocrine hormone release, modulates inflammatory pain and influences blood pressure and inflammation. NPW is studied as a research tool to understand this signalling system; it is not an approved medicine and has not been given to people as a treatment.
No established human dose Details ↓
Recommended Dosing
No established human dose
Neuropeptide W is an endogenous human peptide that has never been given to people as a treatment. The human evidence is anatomy and physiology; the functional studies are in animals and cells, where NPW is infused into the brain or given to rodents at experimental amounts that do not carry over to people.
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What is it?
Neuropeptide W was discovered in the early 2000s during the hunt for the natural ligands of two ‘orphan’ G-protein-coupled receptors, GPR7 and GPR8 (now named NPBWR1 and NPBWR2). Two closely related peptides turned out to fill that role: neuropeptide B (NPB) and neuropeptide W (NPW). NPW is made in the brain — especially the hypothalamus — and in the gut, and exists as a 23- or 30-amino-acid peptide (NPW23 and NPW30), both carrying a signature tryptophan (the single-letter code W) that gives the peptide its name.
The clearest role of NPW is in feeding and energy balance. Infused into the brain, it suppresses food intake and body weight while increasing heat production and body temperature, which is why it is described as an endogenous catabolic (energy-burning) signal. Its receptors and the peptide itself are found throughout the feeding- and energy-regulating nuclei of the hypothalamus.
NPW reaches well beyond appetite. Its receptors are strongly concentrated in the extended amygdala, the brain’s stress-, fear- and emotion-handling region, pointing to a role in the stress response and anxiety. It feeds into neuroendocrine control — in birds it directly inhibits the pituitary release of ACTH, growth hormone and prolactin, acting as a release-inhibiting factor, though the details differ from mammals — and it modulates inflammatory pain, blood pressure and inflammation.
Much of what is known comes from animal and cell work. In rats, NPW given during experimental sepsis lessened oxidative damage across the brain, heart, lung, liver and kidney, in line with its effects on blood pressure and inflammation. At the cellular level, the receptor NPW1/GPR7 was mapped in rat and mouse brain by radioligand binding, and NPW was shown to regulate the growth of cartilage precursor cells through GPR7 and the PKA and PKC signalling pathways — a reminder that this system also touches bone and cartilage growth.
Neuropeptide W is an endogenous human peptide and a research tool, not a medicine. No published study has given NPW to people as a treatment — the human side is anatomy and physiology, and the functional work is in animals and cells — it is approved nowhere, and material sold online as ‘neuropeptide W’ or ‘NPW’ is an unregulated research chemical. Nothing here is a dose or a therapy; this page records what the published science says about the peptide.
Mechanism of Action
Neuropeptide W is an endogenous brain and gut peptide that works through the receptors NPBWR1 (GPR7) and NPBWR2 (GPR8). It suppresses feeding and acts as a catabolic signal, tunes the stress axis and neuroendocrine hormone release, and modulates inflammation and pain.
Feeding and energy balance
Acting through GPR7 and GPR8 in the hypothalamus, NPW suppresses food intake and body weight while raising heat production and body temperature — an endogenous catabolic (energy-burning) signal (PMID 28376284).
Stress axis and neuroendocrine control
Its receptors are concentrated in the extended amygdala, the stress- and emotion-handling region (PMID 18204824), and NPW can inhibit pituitary release of ACTH, growth hormone and prolactin, behaving as a release-inhibiting factor (species-specific; PMID 35583189).
Inflammation, pain and tissue effects
NPW modulates inflammatory pain, blood pressure and inflammation — lessening oxidative organ damage in rat sepsis (PMID 34564825) — and acts through GPR7, PKA and PKC to regulate cartilage-cell growth (PMID 30609248).
Published Research
These are studies of neuropeptide W read from their PubMed abstracts on November 6, 2026. They include two reviews of the NPB/NPW system in energy homeostasis, stress and pain, an animal study of NPW against sepsis-induced organ injury, a study of NPW inhibiting pituitary stress hormones in birds, the identification of its NPW1/GPR7 receptor in rodent brain, and a cell study of NPW in cartilage growth. Neuropeptide W has not been given to people as a treatment in any published study; the human evidence is anatomical and physiological.
The NPB/NPW system in energy, pain and emotion
A review of the neuropeptide B (NPB) and neuropeptide W (NPW) system, the endogenous ligands of the receptors GPR7 (NPBWR1) and GPR8 (NPBWR2). It sets out the system’s roles in feeding behaviour, energy homeostasis, neuroendocrine function and inflammatory pain, and notes that the strong, discrete expression of the receptors in the extended amygdala points to a role in stress, emotion, anxiety and fear — a hypothesis awaiting functional confirmation.
Neuropeptide W in energy homeostasis
A focused review of neuropeptide W as the endogenous ligand of GPR7 and GPR8. It summarises where NPW and its receptors are found in the central nervous system and the periphery, and the evidence that NPW regulates food intake and energy homeostasis — infused centrally it suppresses feeding and body weight while raising heat production, behaving as an endogenous catabolic signal.
NPW lessens organ injury in rat sepsis
In a rat model of intra-abdominal sepsis (cecal ligation and puncture), subcutaneous neuropeptide W given at surgery and repeated over 24 hours reduced the oxidative damage that sepsis caused across the brain, heart, lung, liver and kidney, in line with NPW’s known effects on blood pressure and inflammation. A preclinical result pointing to an anti-inflammatory, organ-protective role, not a human therapy.
NPW inhibits stress hormones in chickens
Characterising the NPB/NPW system in chickens, this study found neuropeptide W could act directly on the pituitary to inhibit the synthesis and secretion of ACTH — the stress hormone — and also of growth hormone and prolactin, through the receptor NPBWR2, behaving as a physiological corticotropin-release inhibitory factor. The mechanism differs from mammals, underscoring that NPW’s neuroendocrine role is species-specific (a preclinical, mechanistic result).
Mapping the NPW1 (GPR7) receptor in rodent brain
Using a radiolabelled form of neuropeptide W, this study identified high-affinity binding sites in rat and mouse brain — densest in the amygdala and thalamic and hypothalamic nuclei — and confirmed them as the receptor NPW1, previously the orphan receptor GPR7. NPW-like immunoreactivity was found in neurons projecting to the amygdala, evidence for an emerging transmitter system (a receptor-localisation study in animal tissue).
NPW regulates cartilage-cell growth via GPR7
In mouse ATDC5 chondrocyte (cartilage precursor) cells, neuropeptide W and its receptor GPR7 were expressed in the growth-plate chondrocytes, and NPW-23 promoted cell proliferation in a way blocked by inhibiting GPR7 and the PKA and PKC signalling pathways. The work extends the NPW system — better known for appetite and energy — to the control of cartilage and bone growth (a cell-culture result).
No Established Human Dose
Neuropeptide W is an endogenous human peptide that has never been given to people as a treatment. The human evidence is anatomy and physiology; the functional studies are in animals and cells, where NPW is infused into the brain or given to rodents at experimental amounts that do not carry over to people. No regulator has approved any dose, and no published human dose exists, so no amount is printed here.
What this rests on: PMID 18204824, PMID 28376284, PMID 34564825.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Neuropeptide W (NPW) is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
Unknown: no human dose of Neuropeptide W (NPW) has been established (see No Established Human Dose below), so there is no amount to work out. The reconstitution calculator does the arithmetic for any vial, water and dose.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Neuropeptide W (NPW), before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Neuropeptide W (NPW) stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Neuropeptide W (NPW). What the human studies gave and how is set out under No Established Human Dose.
What to expect, and when
How long it stays in the body: a half-life of not established for humans as a drug; an endogenous signalling peptide. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for Neuropeptide W (NPW). Results reported in the studies are under Published Research.
Source: half-life: PMID 28376284.
Side effects, and when to stop or get help
From the Side Effects section: No human adverse-event data exist: no published study has administered neuropeptide W to people; In animals, central NPW suppresses appetite and body weight and raises body temperature (PMID 28376284) — effects of a catabolic signal, not a safety profile; NPW influences the stress axis and neuroendocrine hormone release (PMIDs 18204824, 35583189), so systemic effects would be expected if it were administered; Material sold online as ‘neuropeptide W’ or ‘NPW’ is an unregulated research chemical of unverified content. Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Neuropeptide W (NPW). Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Neuropeptide W is an endogenous peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status”).
Interactions
Unknown: a PubMed search for human interaction studies of Neuropeptide W (NPW) (reviewed 2026-11-06) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Neuropeptide W (NPW) products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Research Chemical (Not a drug: Drugs@FDA and the openFDA label endpoint hold no record, and FDA GSRS and ChEMBL hold no substance record for neuropeptide W (searched November 6, 2026)). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
Neuropeptide W is an endogenous peptide that has not been given to people as a drug, so there is no human safety profile; the points below reflect that research status.
Contraindications & Cautions
Neuropeptide W has no approved use and no label. These points reflect its endogenous, research status.
Legal Status
Neuropeptide W is an endogenous human peptide studied as a research compound; it is not a drug and is not approved in any country.
Frequently Asked Questions
?What is neuropeptide W?
An endogenous human peptide of the brain and gut, made in two forms (NPW23 and NPW30). With neuropeptide B it is a natural ligand of the receptors NPBWR1 (GPR7) and NPBWR2 (GPR8), and it is named for a tryptophan (single-letter code W) at each end.
?What does it do?
Its clearest role is suppressing food intake and acting as an energy-burning (catabolic) signal (PMID 28376284). It also tunes the stress axis and neuroendocrine hormone release (PMIDs 18204824, 35583189) and modulates inflammation and pain (PMID 34564825).
?Is it a treatment for anything?
No. Neuropeptide W is a research peptide used to study its signalling system; its receptors are potential drug targets. No human trial has administered it, and it is approved nowhere.
?Is it approved or available to buy?
No. Neuropeptide W is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as neuropeptide W or NPW is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [review] Hondo M, et al. "The NPB/NPW neuropeptide system and its role in regulating energy homeostasis, pain, and emotion." Results Probl Cell Differ, 2008;46:239-56. PMID: 18204824.
- [review] Li H, et al. "The role of neuropeptide W in energy homeostasis." Acta Physiol (Oxf), 2018;222(1). PMID: 28376284.
- [animal] Atici AE, et al. "Neuropeptide W Attenuates Oxidative Multi-Organ Injury in Rats Induced with Intra-Abdominal Sepsis." Inflammation, 2022;45(1):279-296. PMID: 34564825.
- [animal] Liu M, et al. "Evidence for Neuropeptide W Acting as a Physiological Corticotropin-releasing Inhibitory Factor in Male Chickens." Endocrinology, 2022;163(7). PMID: 35583189.
- [mechanism] Singh G, et al. "Identification and cellular localisation of NPW1 (GPR7) receptors for the novel neuropeptide W-23 by [125I]-NPW radioligand binding and immunocytochemistry." Brain Res, 2004;1017(1-2):222-6. PMID: 15261118.
- [mechanism] Wang R, et al. "Neuropeptide W regulates proliferation and differentiation of ATDC5: Possible involvement of GPR7 activation, PKA and PKC-dependent signalling cascades." J Cell Mol Med, 2019;23(3):2093-2102. PMID: 30609248.
- [other] UniProt Q8N729 (NPW_HUMAN), read November 6, 2026: neuropeptide W is the product of the NPW gene, a secreted brain and gut peptide processed into a 23- or 30-amino-acid form (NPW23, NPW30); it signals through the G-protein-coupled receptors NPBWR1 (GPR7) and NPBWR2 (GPR8). https://www.uniprot.org/uniprotkb/Q8N729/entry
- [other] Neuropeptide W was first isolated from the hypothalamus and identified, with neuropeptide B (NPB), as an endogenous ligand of the formerly orphan receptors GPR7 (NPBWR1) and GPR8 (NPBWR2); the NPB/NPW system is reviewed in the energy-homeostasis review carded on this page (read November 6, 2026).
- [other] US FDA, Drugs@FDA and the drug label endpoint (openFDA), searched November 6, 2026: no application and no label record for neuropeptide W. It is an endogenous human peptide, not a registered drug; FDA GSRS and ChEMBL hold no substance record for it.
Sources & Citations
The six studies carded above were read from their PubMed records on November 6, 2026. Identity comes from UniProt (Q8N729, gene NPW); neuropeptide W’s two forms (NPW23, NPW30), its NPBWR1/NPBWR2 (GPR7/GPR8) receptors and its roles in feeding, stress, neuroendocrine release and pain are from the reviews and studies carded here; the absence of US approval and of a drug substance record from Drugs@FDA, openFDA, FDA GSRS and ChEMBL was checked the same day. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.