Page data last changed: . Chemistry registry snapshot: . Registry refreshes and identity assessments are separate from scientific content review.
Opioid-related peptide that acts at the NOP receptor rather than classic opioid receptors.
Also known as: Orphanin FQ · N/OFQ
Part of the Neuropeptides & signaling cluster
Overview
Nociceptin (orphanin FQ) is a 17-amino-acid neuropeptide that binds the NOP receptor, a member of the opioid receptor family. It is studied for its complex roles in pain processing, mood, and stress.
Source & context
Biological / chemical source: Central nervous system; derived from prepronociceptin
Primary research or clinical context: Pain and mood neuroscience research
A distinct opioid-like system
Although related to opioid peptides, nociceptin acts at the NOP (ORL1) receptor rather than mu, delta, or kappa receptors. Its effects on nociception can differ by site of action, making it a nuanced research topic.
Naming origin
The peptide was named 'orphanin FQ' because it was the endogenous ligand for a previously orphan receptor. This page describes that pharmacology for education only.
Sequence
One-letter sequence commonly cited for Nociceptin (educational; isoforms and modifications may differ):
FGGFTGARKSARKLANQ
Residues plotted ~100° apart around an α-helix — clustering of one color reveals an amphipathic face.
Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
Reference values are taken from the cited molecular record or curated profile. A database match is not independent laboratory verification; modifications, counter-ions, and formulations can change the measured mass.
- Molecular form
- Nociceptin (source record; form not independently established)
- Species
- Not established by this molecular identity audit
- Termini (N / C)
- Not specified / Not specified
Average reference mass
Reference policy updated: 2026-10-05
- IUPHAR/BPS source snapshot · 2026-10-01
- PubChem molecular record · 2026-10-01
- Molecular formula
- C79H129N27O22
- Average reference mass
- ≈ 1,809
- PubChem CID: 16131448
- IUPHAR ligand: 1681
- ChEMBL: CHEMBL396460
- CAS RN: 170713-75-4
- UNII: 7AYI9N34FF
Chemistry values: PubChem, IUPHAR/BPS Guide to Pharmacology · fetched 2026-10-01.
Clinical development snapshot
ClinicalTrials.gov lists 19 registered studies with “Nociceptin” as an intervention (snapshot 2026-09-06). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT07663682 | Correlation Between Serum Nociceptin and Sympathetic Nerve Activity in Diabetic Patients With MAFLD | — | completed | 2026-06-23 |
| NCT07595887 | Ultrasound Assessment of Sciatic Nerve and Inferior Gluteal Artery in Diabetic Peripheral Neuropathy(DPN): Ass | — | not yet recruiting | 2026-06-16 |
| NCT07612631 | Imaging CRF X NOP Interactions in Alcohol Use Disorder | Early phase 1 | recruiting | 2026-06-03 |
| NCT05232032 | Pharmaco-Neuroimaging Studies of Approach/Avoidance Behaviors and Post-Mortem Studies: Pharmacological Manipul | Phase 2 | recruiting | 2026-05-18 |
| NCT05630963 | Beyond Monoamines: The Role of the Nociceptin/Orphanin FQ Receptor in Major Depression | — | recruiting | 2025-10-21 |
| NCT06786637 | Investigating the Protective Impact of LY-2940094 on Stress-induced Depression- and Anxiety-related Phenotypes | Phase 2 | withdrawn | 2025-09-25 |
Nociceptin — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Nociceptin (source record; form not independently established)Average reference mass: 1,809 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
FAQ about Nociceptin
What is Nociceptin?+
Nociceptin (orphanin FQ) is a 17-amino-acid neuropeptide that binds the NOP receptor, a member of the opioid receptor family. It is studied for its complex roles in pain processing, mood, and stress.
What Canadian product status is recorded for Nociceptin?+
Canadian product status for Nociceptin has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the typical length of Nociceptin?+
Nociceptin is commonly described as approximately 17 amino acids (Neuropeptide).
Related peptides
References & further reading
- 1.Calo' et al. (2000). Nociceptin/orphanin FQ receptor ligands. Peptides
- 2.Dooley et al. (2000). Orphanin FQ/nociceptin receptor binding studies. Peptides
- 3.Angelico et al. (2019). Nociceptin/Orphanin FQ and Urinary Bladder. Handb Exp Pharmacol
- 4.Domi et al. (2022). Genetic deletion or pharmacological blockade of nociceptin/orphanin FQ receptors in the ventral tegmental area attenuates nicotine-motivated behaviour. Br J Pharmacol
- 5.Baiula et al. (2015). Role of nociceptin/orphanin FQ in thermoregulation. Neuropeptides
- 6.Giakomidi et al. (2022). Nociceptin/Orphanin FQ receptor expression in primary human umbilical vein endothelial cells is not regulated by exposure to breast cancer cell media or angiogenic stimuli. BJA Open
- 7.El Daibani et al. (2022). Spotlight on Nociceptin/Orphanin FQ Receptor in the Treatment of Pain. Molecules
- 8.Yamamoto et al. (1999). Nociceptin/orphanin FQ: role in nociceptive information processing. Prog Neurobiol
- 9.PubChem — compound summary for Nociceptin (CID 16131448)
- 10.Wikipedia — Nociceptin