Neuropeptide B (NPB)
An endogenous brain peptide, the GPR7-selective partner of neuropeptide W, that tunes appetite, sleep and pain. A research peptide, not a drug
Neuropeptide B (NPB) is an endogenous brain peptide and the sister of neuropeptide W (NPW). The two were found together as the natural ligands of a pair of receptors — NPBWR1 (originally GPR7) and NPBWR2 (originally GPR8) — but NPB is more selective, acting mainly through GPR7. It carries an unusual chemical signature: a bromine atom on the tryptophan at the start of the molecule, one of the few brominated peptides known in mammals. Through its receptors NPB helps regulate appetite, body weight and metabolism, promotes slow-wave (deep) sleep, tunes the release of stress and pituitary hormones, and dampens inflammatory pain. Deleting NPB or its receptor makes animals mildly obese, marking it as part of the body’s energy-balance machinery. NPB 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 B 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 NPB is injected into the brain or spinal fluid or applied to cells at experimental amounts that do not carry over to people.
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What is it?
Neuropeptide B was purified from the hypothalamus in the early 2000s as one of the two endogenous ligands that filled the ‘orphan’ receptors GPR7 and GPR8 (now NPBWR1 and NPBWR2). The other ligand, found alongside it, was neuropeptide W. Both are small brain peptides with a tryptophan (single-letter code W) at the start, and NPB is distinctive for carrying a bromine atom on that tryptophan — a rare modification among mammalian peptides. NPB binds GPR7 with sub-nanomolar potency and is more selective for GPR7 than NPW, which hits both receptors equally.
The system’s best-mapped role is in appetite and energy balance. NPB and its receptors sit in the feeding-regulating nuclei of the hypothalamus and in peripheral tissues, and the peptide circulates in the blood. Deleting either NPB or its receptor GPR7 produces mild, gender-skewed obesity and overeating in mice — direct evidence that NPB is part of the machinery holding body weight in check — and in fat cells NPB shifts the secretion of leptin and resistin and drives fat breakdown (lipolysis).
NPB does much more than feeding. Injected into the brain, it promotes slow-wave (deep) sleep through GPR7, a role not shared equally by NPW. It modulates neuroendocrine output, changing the release of corticosterone, prolactin and growth hormone, and — given into the spinal fluid — it blunts inflammatory pain without acting through opioid receptors, a non-opioid analgesic effect of interest in pain research.
Because the receptors are drug targets, chemists have built better tools around NPB. A systematic structure-activity study showed that the N-terminal tryptophan is essential for binding and produced analogues that are potent and highly selective for GPR7, intended as pharmacological probes of the system rather than as medicines.
Neuropeptide B is an endogenous human peptide and a research tool, not a medicine. No published study has given NPB 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 B’ or ‘NPB’ 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 B is an endogenous brain peptide that works mainly through the receptor NPBWR1 (GPR7), with its sister peptide neuropeptide W. It helps regulate appetite and energy balance, promotes slow-wave sleep, tunes neuroendocrine hormone release, and dampens inflammatory pain.
Appetite, energy and metabolism
Through GPR7 (and GPR8 in humans) in the hypothalamus and fat tissue, NPB regulates feeding and energy balance — losing NPB or its receptor causes obesity (PMID 34205710) — and in fat cells it shifts leptin and resistin and drives lipolysis (PMID 22484289).
Sleep and neuroendocrine control
NPB promotes slow-wave (deep) sleep through GPR7 (PMID 21203369) and tunes the release of corticosterone, prolactin and growth hormone (PMID 16847439) — a neuroendocrine as well as a metabolic peptide.
Non-opioid pain modulation
Given into the spinal fluid, NPB blunts inflammatory pain and mechanical allodynia without acting through opioid receptors (PMID 15910767); its GPR7-selective analogues are built as tools to probe these effects (PMID 17486669).
Published Research
These are studies of neuropeptide B read from their PubMed abstracts on November 6, 2026. They include two reviews of the NPB/NPW system and NPB’s role in appetite and metabolism, an animal study of NPB inducing slow-wave sleep, an animal study of its anti-pain effect in the spinal cord, a cell study of its effects on fat-cell hormones and fat breakdown, and a medicinal-chemistry study that built a GPR7-selective NPB analogue. Neuropeptide B has not been given to people as a treatment in any published study; the human evidence is anatomical and physiological.
Neuropeptide B in appetite, metabolism and energy
A review of neuropeptide B and its receptors NPBWR1 (GPR7) and NPBWR2 (GPR8). In the brain NPB modulates appetite, reproduction, pain, anxiety and emotion; in the periphery it influences adrenal hormones, pancreatic beta cells and adipose tissue. The authors highlight that experimentally lowering NPB or its receptor NPBWR1 leads to adiposity — placing NPB among the signals that control metabolism and energy homeostasis.
NPB and W as an emerging transmitter system
A review of neuropeptide B and W as the endogenous ligands of GPR7 (NPBW1) and GPR8 (NPBW2). It maps their expression — highest in the amygdala and feeding-related hypothalamic nuclei — and notes that brain infusion of these ligands modulates feeding and the release of corticosterone, prolactin and growth hormone while influencing pain. Knockout of NPB or its receptor gives a gender-specific phenotype, with moderate obesity in males.
Neuropeptide B induces slow-wave sleep in mice
Injected into the brain of mice, neuropeptide B reduced waking and increased the time spent in slow-wave (deep) sleep during the dark period, with the spectral quality of the induced sleep indistinguishable from natural slow-wave sleep. The effect was absent in GPR7-knockout mice, showing it works through GPR7 — evidence that NPB and GPR7 help modulate sleep and wakefulness (a preclinical result).
NPB blunts inflammatory pain in the spinal cord
Given into the spinal fluid of rats, neuropeptide B (and neuropeptide W-23) reduced pain behaviours from paw formalin or carrageenan injection and lessened mechanical allodynia, without affecting simple heat pain, and suppressed the spinal pain-signalling marker c-Fos. Naloxone did not block the effect, so the analgesia is non-opioid — identifying this system as a spinal pain modulator (a preclinical result).
NPB shifts fat-cell hormones and drives lipolysis
In isolated rat fat cells, which express the GPR7 receptor, neuropeptide B and neuropeptide W lowered the secretion and expression of leptin, NPB raised resistin, and both peptides increased fat breakdown (lipolysis) — effects presumed to run through GPR7. The authors proposed these as mechanisms by which the NPB/NPW system could affect glucose and lipid balance and food intake (a cell-culture result).
A potent, GPR7-selective NPB analogue
A systematic structure-activity study of neuropeptide B confirmed that its N-terminal tryptophan is essential for binding and that several positions tolerate substitution. Replacing a stretch of the middle residues with flexible linkers kept potent activity at GPR7, and two analogues reached parent-peptide potency at GPR7 with markedly reduced activity at GPR8 — giving potent, GPR7-selective tools to probe the system (a medicinal-chemistry result, not a therapy).
No Established Human Dose
Neuropeptide B 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 NPB is injected into the brain or spinal fluid or applied to cells 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 34205710, PMID 21203369, PMID 15910767.
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 B (NPB) 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 B (NPB) 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 B (NPB), 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 B (NPB) stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking Neuropeptide B (NPB). 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 B (NPB). Results reported in the studies are under Published Research.
Source: half-life: PMID 34205710.
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 B to people; In animals, central NPB promotes deep sleep and reduces locomotor activity (PMID 21203369) and alters feeding and energy balance (PMID 34205710) — effects of a signalling peptide, not a safety profile; NPB changes the release of stress and pituitary hormones (PMID 16847439), so systemic effects would be expected if it were administered; Material sold online as ‘neuropeptide B’ or ‘NPB’ 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 B (NPB). Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“Neuropeptide B 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 B (NPB) (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 B (NPB) 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 B (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 B 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 B has no approved use and no label. These points reflect its endogenous, research status.
Legal Status
Neuropeptide B 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 B?
An endogenous human brain peptide and the sister of neuropeptide W. With NPW it is a natural ligand of the receptors NPBWR1 (GPR7) and NPBWR2 (GPR8), though NPB is selective for GPR7. It carries a distinctive bromine atom on the tryptophan at the start of the molecule.
?What does it do?
It helps regulate appetite, metabolism and energy balance — losing it causes obesity in mice (PMID 34205710) — promotes slow-wave (deep) sleep (PMID 21203369), tunes stress and pituitary hormone release (PMID 16847439) and blunts inflammatory pain without opioids (PMID 15910767).
?Is it a treatment for anything?
No. Neuropeptide B is a research peptide used to study its signalling system; its receptors are potential drug targets, and GPR7-selective analogues have been built as tools (PMID 17486669). No human trial has administered NPB, and it is approved nowhere.
?Is it approved or available to buy?
No. Neuropeptide B is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as neuropeptide B or NPB is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [review] Wojciechowicz T, et al. "The Role of Neuropeptide B and Its Receptors in Controlling Appetite, Metabolism, and Energy Homeostasis." Int J Mol Sci, 2021;22(12). PMID: 34205710.
- [review] Singh G, et al. "Neuropeptide B and W: neurotransmitters in an emerging G-protein-coupled receptor system." Br J Pharmacol, 2006;148(8):1033-41. PMID: 16847439.
- [animal] Hirashima N, et al. "Neuropeptide B induces slow wave sleep in mice." Sleep, 2011;34(1):31-7. PMID: 21203369.
- [animal] Yamamoto T, et al. "Anti-hyperalgesic effects of intrathecally administered neuropeptide W-23, and neuropeptide B, in tests of inflammatory pain in rats." Brain Res, 2005;1045(1-2):97-106. PMID: 15910767.
- [mechanism] Skrzypski M, et al. "Neuropeptide B and W regulate leptin and resistin secretion, and stimulate lipolysis in isolated rat adipocytes." Regul Pept, 2012;176(1-3):51-6. PMID: 22484289.
- [mechanism] Kanesaka M, et al. "Development of a potent and selective GPR7 (NPBW1) agonist: a systematic structure-activity study of neuropeptide B." J Pept Sci, 2007;13(6):379-85. PMID: 17486669.
- [other] UniProt Q8NG41 (NPB_HUMAN), read November 6, 2026: neuropeptide B is the product of the NPB gene, a secreted brain peptide that carries a 6-bromo-tryptophan at its N terminus; it signals through the G-protein-coupled receptors NPBWR1 (GPR7) and NPBWR2 (GPR8). https://www.uniprot.org/uniprotkb/Q8NG41/entry
- [other] Neuropeptide B was purified from bovine hypothalamus as an endogenous ligand of the formerly orphan receptor GPR7 (NPBWR1), and a paralogous peptide, neuropeptide W (NPW), was identified alongside it; both carry an N-terminal tryptophan (Tanaka et al., Proceedings of the National Academy of Sciences USA, 2003, 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 B. 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 (Q8NG41, gene NPB); neuropeptide B’s N-terminal 6-bromo-tryptophan, its NPBWR1/NPBWR2 (GPR7/GPR8) receptors, its selectivity for GPR7 and its roles in appetite, sleep, neuroendocrine release and pain are from the reviews and studies carded here and the discovery paper cited in the sources above; 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.