QRFP (26RFa)
An endogenous appetite-stimulating neuropeptide that acts through the GPR103 receptor — driving food intake and activity and tuning blood-sugar control; studied in the lab, not a drug
QRFP, also called 26RFa, is a small human neuropeptide of the RFamide family, found in 2003. It is made mainly in the hypothalamus, the brain’s appetite and energy-control centre, and it acts through a receptor called GPR103. QRFP is orexigenic — it increases appetite, especially for high-fat food — and it also raises physical activity and plays a part in blood-sugar control, acting a little like an incretin to help the pancreas release insulin. It comes in two lengths, a 26-amino-acid form (26RFa) and a longer 43-amino-acid form (43RFa), cut from the same precursor. Beyond appetite and glucose, QRFP has roles in bone formation and in how the body processes pain. QRFP is an endogenous peptide studied as a research tool; 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
QRFP is an endogenous neuropeptide that has never been given to people as a treatment. It is studied in animals and cells — given into the brain of rodents to probe appetite and glucose control, or added to cultured cells — not administered to patients.
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What is it?
QRFP belongs to the RFamide family of neuropeptides — named for the arginine-phenylalanine-amide (Arg-Phe-NH2) signature at their tail. It was discovered in 2003 by three groups at once, one of which named it 26RFa and another QRFP, for pyroglutamylated RFamide peptide; both names are still used. It is the natural ligand of GPR103, a receptor that had been an ‘orphan’ until QRFP was matched to it.
The peptide is made mainly in the hypothalamus, and its headline role is to stimulate appetite. Given into the brain of rodents, QRFP increases food intake — with a particular pull toward high-fat, palatable food — and also raises locomotor activity and arousal. It does this partly by switching on the orexin (hypocretin) neurons of the lateral hypothalamus: in mice, the feeding response to QRFP depends on orexin-receptor signalling, while the increased movement does not, so QRFP drives both the wanting and the eating through overlapping circuits.
QRFP’s second major role is in blood-sugar control. It behaves a little like an incretin — the gut signals that prime insulin release after a meal — enhancing glucose-stimulated insulin secretion and improving insulin sensitivity. In lean animals this is a tidy regulatory loop, and a single central dose of 26RFa lowered high blood sugar in obese, diabetic mice. But the system breaks down in disease: in diet-induced obese mice the QRFP/GPR103 response is blunted and its receptor is turned down, so the glucose-lowering effect is lost, and chronic QRFP instead adds weight by driving appetite. The shorter 26RFa form carries most of the metabolic muscle effect — it enhanced insulin-stimulated glucose uptake in rat muscle cells, where the longer 43RFa did not.
QRFP’s wider biology, mapped in an IUPHAR review, extends to bone formation, pain processing (nociception) and fat-tissue regulation (adipogenesis and lipolysis), and its receptor is found not only in the brain but in bone, heart, kidney, pancreas and testis. Because the system reaches across appetite, metabolism, bone and pain, both agonists and antagonists of the QRFP receptor have been explored as research tools and potential drug leads.
QRFP is an endogenous human neuropeptide and a research tool, not a medicine. No published study has given QRFP to people as a treatment — the work is in animals and cells — it is approved nowhere, and material sold online as ‘26RFa’ or ‘QRFP’ 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
QRFP is an RFamide neuropeptide that works through the receptor GPR103. From the hypothalamus it drives appetite and activity — partly via orexin neurons — and it tunes blood-sugar control, an effect that is lost in obesity.
GPR103 (the QRFP receptor)
QRFP’s two forms, 26RFa and 43RFa, both activate GPR103 (QRFPR; two isoforms in rodents), a G-protein-coupled receptor found in brain, bone, heart, kidney, pancreas and testis — the single receptor through which its wide effects run (PMID 28613414).
Appetite and activity via orexin
From the hypothalamus, QRFP stimulates food intake (especially of high-fat food) and raises locomotor activity, switching on the orexin/hypocretin neurons; the feeding depends on orexin receptor-1 signalling (PMIDs 36251705, 36690209).
Glucose homeostasis, broken in obesity
QRFP acts incretin-like to enhance insulin secretion and sensitivity and lowers high blood sugar acutely (PMID 35093951), but in diet-induced obesity its receptor is downregulated and the glucose-lowering effect is lost (PMID 31084498); the 26RFa form enhances insulin action in muscle cells (PMID 25895849).
Published Research
These are studies of QRFP read from their PubMed abstracts on November 6, 2026. They cover the IUPHAR review of the peptide and its receptor, its role as a regulator of glucose homeostasis (and how that fails in obesity), its stimulation of feeding and activity through GPR103 and orexin receptors, its control of high-fat-diet intake after ovariectomy, and its enhancement of insulin action in muscle cells. QRFP has not been given to people as a treatment in any published study; the work is in animals and cells.
IUPHAR review of 26RFa/QRFP and its receptor
The definitive review of the 26RFa/QRFP–GPR103 system. 26RFa was first isolated from frog brain and, with its extended form QRFP, identified as the ligand of the former orphan receptor GPR103 (now the QRFP receptor). In mammals the peptide is made almost only in hypothalamic nuclei, and the receptor is widespread in brain and peripheral tissues (bone, heart, kidney, pancreas, testis). QRFP controls energy homeostasis, bone formation and nociception, and selective agonists and antagonists have been developed as tools and potential drug leads.
QRFP a key regulator of glucose homeostasis
In mice, blocking the QRFP receptor reduced the incretin effect and insulin sensitivity, while giving QRFP attenuated glucose-induced hyperglycemia — marking QRFP as a key regulator of glucose homeostasis. In diet-induced obese, hyperglycemic mice this action was lost: the insulin-stimulating and insulin-sensitising effects of QRFP disappeared, its receptor was downregulated in pancreatic islets and insulin-target tissues, and the peptide’s release kinetics were altered — a resistance that develops in obesity.
Acute 26RFa improves glucose in diabetic mice
A single central injection of 26RFa produced a robust anti-hyperglycemic effect in obese, high-fat-fed mice by enhancing insulin secretion — the beneficial glucose action was preserved even in the diabetic state. Chronic central 26RFa, by contrast, did not improve glucose control and instead increased body weight, food intake and reduced energy expenditure, suggesting the system mainly governs short-term glucose regulation (a preclinical result).
QRFP increases feeding and activity via GPR103 and orexin
Central QRFP increased both food intake and locomotor activity in mice, without changing energy expenditure, thermogenesis or reward. Both QRFP receptor genes (Gpr103a and Gpr103b) were needed for the effect, and QRFP activated the orexin/hypocretin neurons of the lateral hypothalamus. The feeding response — but not the increase in movement — was blocked by an orexin receptor-1 antagonist, so QRFP drives both appetitive and consummatory behaviour, with the eating depending on orexin signalling.
QRFP and high-fat-diet intake after ovariectomy
In female rats, the orexigenic peptide QRFP increased high-fat-diet intake, and it is overexpressed after ovariectomy (a model of estrogen deficiency). Giving 26RFa raised high-fat intake and body weight, oestrogen treatment blunted that effect, and knocking down QRFP in the hypothalamus with siRNA cut high-fat intake and weight gain — supporting QRFP as a driver of palatable-food intake and weight gain when oestrogen is low.
QRFP-26 enhances insulin action in muscle cells
In rat skeletal-muscle cells (L6 myotubes), which express QRFP and its receptor GPR103a, co-incubation with the shorter QRFP-26 form increased insulin’s ability to drive glycogen synthesis and glucose uptake, while the longer QRFP-43 did not. The result points to QRFP-26 as a modulator of insulin action in muscle, a major consumer of circulating glucose.
No Established Human Dose
QRFP is an endogenous neuropeptide that has never been given to people as a treatment. It is studied in animals and cells — given into the brain of rodents to probe appetite and glucose control, or added to cultured cells — not administered to patients. No regulator has approved any dose, and the animal and cell studies used QRFP at experimental amounts that do not carry over to people, so no amount is printed here.
What this rests on: PMID 31084498, PMID 35093951, PMID 25895849.
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 QRFP (26RFa) 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 QRFP (26RFa) 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 QRFP (26RFa), 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 QRFP (26RFa) stays intact once mixed.
How it is taken
Unknown: with no established human dose, there is no established way of taking QRFP (26RFa). 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; an endogenous, centrally acting neuropeptide. After about five half-lives almost none is left.
When effects appear: unknown; no source on this page gives a time to effect for QRFP (26RFa). Results reported in the studies are under Published Research.
Source: half-life: PMID 31084498.
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 QRFP to people; In animals it is orexigenic — it increases appetite, high-fat-food intake and body weight (PMIDs 36690209, 35093951); Its metabolic effects are context-dependent and are lost in obesity, where its receptor is downregulated (PMID 31084498); Material sold online as ‘26RFa’ or ‘QRFP’ 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 QRFP (26RFa). Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“QRFP 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 QRFP (26RFa) (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 QRFP (26RFa) 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 QRFP / 26RFa (searched November 6, 2026)). Sport: Not on the 2026 List.
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Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
QRFP 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
QRFP has no approved use and no label. These points reflect its endogenous, research status.
Legal Status
QRFP (26RFa) is an endogenous human neuropeptide studied as a research compound; it is not a drug and is not approved in any country.
Frequently Asked Questions
?What is QRFP?
An endogenous human neuropeptide, also called 26RFa, discovered in 2003. It is an RFamide-family peptide made mainly in the hypothalamus and acting through the receptor GPR103; it comes in a 26- and a 43-amino-acid form.
?What does it do?
It stimulates appetite — especially for high-fat food — and raises activity, partly by switching on orexin neurons (PMID 36251705), and it helps control blood sugar in an incretin-like way (PMID 31084498). It also affects bone and pain.
?Is it a weight-loss or diabetes drug?
No. QRFP increases appetite and body weight, so it is not a weight-loss agent. Its glucose-lowering effect is interesting but is lost in obesity (PMID 31084498), and no human trial has given QRFP to people. It is approved nowhere.
?Is it approved or available to buy?
No. QRFP is not a medicine, has no FDA application or label, and is approved nowhere. Material sold online as 26RFa or QRFP is an unregulated research chemical. Grey Peptides lists no sellers and recommends no source; this page records the published science.
References
- [review] Leprince J, et al. "The Arg-Phe-amide peptide 26RFa/glutamine RF-amide peptide and its receptor: IUPHAR Review 24." Br J Pharmacol, 2017;174(20):3573-3607. PMID: 28613414.
- [animal] Prévost G, et al. "Neuropeptide 26RFa (QRFP) is a key regulator of glucose homeostasis and its activity is markedly altered in obese/hyperglycemic mice." Am J Physiol Endocrinol Metab, 2019;317(1):E147-E157. PMID: 31084498.
- [animal] Le Solliec MA, et al. "Acute but Not Chronic Central Administration of the Neuropeptide 26RFa (QRFP) Improves Glucose Homeostasis in Obese/Diabetic Mice." Neuroendocrinology, 2022;112(11):1104-1115. PMID: 35093951.
- [animal] Cook C, et al. "The hypothalamic RFamide, QRFP, increases feeding and locomotor activity: The role of Gpr103 and orexin receptors." PLoS One, 2022;17(10):e0275604. PMID: 36251705.
- [animal] Martin CT, et al. "The hypothalamic neuropeptide, QRFP, regulates high fat diet intake in female Long-Evans rats following ovariectomy." Peptides, 2023;162:170960. PMID: 36690209.
- [mechanism] Allerton TD, et al. "QRFP-26 enhances insulin's effects on glucose uptake in rat skeletal muscle cells." Peptides, 2015;69:77-9. PMID: 25895849.
- [other] UniProt P83859 (QRFP_HUMAN), read November 6, 2026: QRFP is the product of the QRFP gene, a secreted, C-terminally amidated RFamide neuropeptide that exists as a 26-amino-acid form (26RFa) and a 43-amino-acid form (43RFa); it is the natural ligand of the receptor GPR103 (the QRFP receptor). https://www.uniprot.org/uniprotkb/P83859/entry
- [other] QRFP / 26RFa was discovered independently by three laboratories in 2003 as a new RFamide neuropeptide and the natural ligand of the former orphan receptor GPR103; its forms, receptor and physiology are set out in the IUPHAR 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 QRFP / 26RFa. It is an endogenous human neuropeptide, 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 (P83859, gene QRFP); QRFP’s 2003 discovery, its two forms and its GPR103 receptor are from the IUPHAR review 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.