Peptides
Oxytocin
5mg
Cyclic nonapeptide. Social behaviour and receptor research.
98.39% purity · Supplier-reported analysis · Batch UKPL-9512 · View certificate
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- Add £44.01 more for free UK delivery
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- Research use only. For in-vitro laboratory research. Not for use in humans or animals, or in food, drugs or diagnostics. Not evaluated by the MHRA or FDA. The buyer is responsible for handling and regulatory compliance.
Bulk Pricing
Counted across your basket, any mix of products.
| Vials in basket | Discount | Per vial |
|---|---|---|
| 1 | None | £24.99 |
| 3-4 | 5% | £23.74save £1.25 |
| 5-9 | 8% | £22.99save £2.00 |
| 10-50 | 12% | £21.99save £3.00 |
Bacteriostatic Water 10ml
Required to reconstitute lyophilised peptides.
What is Oxytocin?
Oxytocin is a cyclic nonapeptide, Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, closed by a disulphide bridge between its two cysteines. It is one of the most heavily studied neuropeptides, with research on social behaviour, pair bonding, stress and receptor pharmacology.
Full description
In one-letter code it is CYIQNCPLG-NH₂. Its formula is C₄₃H₆₆N₁₂O₁₂S₂, its molecular weight 1007.19 g/mol and its CAS number 50-56-6. A disulphide bridge between cysteines 1 and 6 closes a twenty-atom ring, and the C-terminus is an amide.
Du Vigneaud, Ressler and Trippett (J Biol Chem, 1953) published the sequence and proposed structure. Du Vigneaud's group reported the first synthesis the same year (J Am Chem Soc, 1953), work recognised by the 1955 Nobel Prize in Chemistry. In the body it is made mainly in the paraventricular and supraoptic nuclei of the hypothalamus and released from the posterior pituitary. Oxytocin is also a licensed prescription medicine. The lyophilised powder sold here is a research reagent, not a pharmaceutical product. Each Oxytocin 5mg vial holds white lyophilised powder.
Oxytocin Research Applications
- Receptor pharmacology: oxytocin is the reference agonist at OXTR, a class A GPCR coupled mainly through Gq to phospholipase C (Gimpl and Fahrenholz, Physiol Rev, 2001).
- Binding assays: the high-affinity receptor state needs both Mg2+ and cholesterol, which matters for buffer and membrane preparation (Gimpl and Fahrenholz, 2001).
- Structural biology: Waltenspühl and colleagues (Sci Adv, 2020) solved the crystal structure of the human oxytocin receptor bound to retosiban, a non-peptide antagonist.
- Pair bonding: prairie vole work links oxytocin signalling to partner preference (Insel and Hulihan, Behav Neurosci, 1995; Donaldson and Young, Science, 2008).
- Stress research: Grinevich and Neumann (Mol Psychiatry, 2021) review its anti-stress effects and their translation to psychiatry.
Study details
The oxytocin system has drawn nearly 25,000 publications since 1930 (Jurek and Neumann, Physiol Rev, 2018). Typical in-vitro work uses binding and calcium mobilisation assays in OXTR-transfected cell lines. Other models cover myometrial contraction and mammary myoepithelial cells. The human social-cognition strand is contested. A well-known study on trust (Kosfeld et al., Nature, 2005) has not replicated reliably (Nave et al., Perspect Psychol Sci, 2015).
Oxytocin vs Vasopressin
Oxytocin and arginine vasopressin are the two cyclic nonapeptides of the posterior pituitary. They differ at two positions. Vasopressin (CYFQNCPRG-NH₂) has phenylalanine at 3 and arginine at 8, where oxytocin has isoleucine and leucine. Oxytocin acts mainly at the oxytocin receptor (OXTR). Vasopressin acts at the V1a, V1b and V2 receptors, with some cross-binding at higher concentrations. So the two are not interchangeable tools. Residues 3 and 8 are the classic handles for analogue design.
Research Overview
Oxytocin is a cyclic nonapeptide with the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, written CYIQNCPLG-NH₂, molecular formula C₄₃H₆₆N₁₂O₁₂S₂, molecular weight 1007.19 g/mol and CAS number 50-56-6. Its defining structural feature is the disulphide bridge joining the cysteine residues at positions 1 and 6, which closes the molecule into a twenty-atom ring and constrains the conformation of the backbone; the C-terminus is a primary amide, and both features are conserved across the vasotocin-oxytocin peptide family. The sequence, and the proposal that the cysteines are bridged, were published by du Vigneaud, Ressler and Trippett (J Biol Chem, 1953), and the first synthesis of the molecule was reported by du Vigneaud and colleagues (J Am Chem Soc, 1953), work that earned the 1955 Nobel Prize in Chemistry. Oxytocin is one of the most heavily studied neuropeptides in the literature.
Mechanistically, oxytocin acts at the oxytocin receptor (OXTR), a class A G-protein-coupled receptor coupled through Gq/11 and phospholipase C, expressed in uterine smooth muscle, mammary myoepithelial cells and a wide set of central nervous system structures. The receptor system was catalogued in depth by Gimpl and Fahrenholz (Physiol Rev, 2001) and updated by Jurek and Neumann (Physiol Rev, 2018), and the human receptor structure was solved in complex with a ligand by Waltenspühl and colleagues (Sci Adv, 2020), which opened structural biology work on OXTR. Research use of the peptide spans receptor binding and calcium mobilisation assays, structural studies, and behavioural neuroscience models of social behaviour and pair bonding (Insel and Hulihan, Behav Neurosci, 1995; Donaldson and Young, Science, 2008).
Two honest points belong up front. First, oxytocin is a licensed human pharmaceutical in injectable formulations, and in the UK those products are prescription-only medicines. The lyophilised material supplied here is not a pharmaceutical product: it is an analytical reference material for in-vitro laboratory research, and it is not supplied for, and must not be used for, human or veterinary administration. Second, the popular account of oxytocin as a trust or love hormone runs well ahead of the evidence. The influential human study reporting increased trust after oxytocin administration (Kosfeld et al., Nature, 2005) has not replicated robustly, and Nave and colleagues (Perspect Psychol Sci, 2015) concluded that the cumulative human data do not provide convergent evidence that trust is reliably caused by oxytocin.
That gap between the animal social behaviour literature, which is comparatively strong, and the human social cognition literature, which is contested, is part of what makes oxytocin a productive research subject. It is supplied as lyophilised powder, supplier-tested, with the certificate published on this page and independent third-party verification pending.
Product Specifications
- Molecular Formula
- C₄₃H₆₆N₁₂O₁₂S₂
- Molecular Weight
- 1007.19 g/mol
- CAS Number
- 50-56-6
- Sequence
- Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, disulphide bridge Cys1-Cys6
- Purity
- 98.39%
- Batch
- UKPL-9512
- Storage
- -20°C lyophilised, 2-8°C reconstituted
- Appearance
- White lyophilised powder
- Form
- Lyophilised powder
Certificate of Analysis
Supplier-reported analysis. Independent third-party verification pending.
- Batch
- UKPL-9512
- Purity
- 98.39%
- Specification
- ≥98.0%
- Method
- RP-HPLC
- Tested
- Sep 2026
Need the certificate for an earlier batch? Request an older CoA
Storage and Reconstitution
Move vials to the freezer on arrival and keep them dark and dry. In solution oxytocin degrades by deamidation and by disulphide exchange. Disulphide scrambling forms dimers and related species that show as new RP-HPLC peaks, and repeated freeze-thaw speeds this up. Keep vials sealed with little headspace and aliquot the solution instead of reopening one stock.
Vials are sold on their own, without bacteriostatic water for mixing or other supplies.
How to reconstitute and handle
Let the vial reach room temperature. Wipe the stoppers of the peptide vial and the bacteriostatic water vial with an alcohol swab. Add the water slowly down the inside wall of the vial, not onto the powder. Swirl gently until it dissolves, and do not shake or vortex. The solution should be clear and colourless. Label the vial with the date.
- The Cys1-Cys6 disulphide bridge is the oxidation-sensitive site: minimise headspace and stopper-open time, work away from strong light, and re-seal promptly after each draw.
- Avoid repeated freeze-thaw cycles. Prepare single-use aliquots at reconstitution and label each with the reconstitution date. Handle under sterile laboratory conditions throughout; this material is a research reagent, not a pharmaceutical product.
For the full method, see the peptide reconstitution guide and the reconstitution calculator.
Research References
- The sequence of amino acids in oxytocin, with a proposal for the structure of oxytocin (du Vigneaud, Ressler and Trippett, J Biol Chem, 1953)
- The oxytocin receptor system: structure, function, and regulation (Gimpl and Fahrenholz, Physiol Rev, 2001)
- Oxytocin, vasopressin, and the neurogenetics of sociality (Donaldson and Young, Science, 2008)
- Crystal structure of the human oxytocin receptor (Waltenspühl et al., Sci Adv, 2020)
Published research on Oxytocin is indexed on PubMed. See our full UK buyer's guide for Oxytocin.
Oxytocin Price (UK)
Oxytocin 5mg is for sale at £24.99 per vial, supplied from stock in the UK with a published supplier batch certificate. UK delivery is £4.50 by Royal Mail Tracked 24, free over £69.
| Vial | Price | Cost per mg | Availability |
|---|---|---|---|
| Oxytocin 5mgThis page | £24.99 | £5.00 | In stock |
Prices are in GBP per vial and match the basket. See the FAQ for delivery and payment options, and quality & testing for how each batch is checked.
Frequently Asked Questions
How does oxytocin work at the molecular level?
Oxytocin acts at the oxytocin receptor (OXTR), a class A G-protein-coupled receptor coupled through Gq/11 to phospholipase C and calcium mobilisation (Gimpl and Fahrenholz, Physiol Rev, 2001; Jurek and Neumann, Physiol Rev, 2018). The crystal structure of the human receptor in complex with a ligand was solved by Waltenspühl and colleagues (Sci Adv, 2020). These are the mechanistic references for receptor binding, calcium flux and structural work with the peptide in vitro.
Is oxytocin a licensed medicine?
Yes. Injectable oxytocin formulations are licensed human pharmaceuticals, and in the UK they are prescription-only medicines. That licensed status applies to the pharmaceutical products, not to this material: the lyophilised oxytocin supplied here is an analytical reference material for in-vitro laboratory research, and it is not supplied for, and must not be used for, human or veterinary administration. No therapeutic use is suggested or implied.
What does the pair bonding research show?
The foundational work is in prairie voles: Insel and Hulihan (Behav Neurosci, 1995) reported that oxytocin administered to female voles facilitated partner preference formation, establishing the receptor-specific model of pair bonding later generalised by Insel and Young (Nat Rev Neurosci, 2001) and reviewed alongside the receptor genetics by Donaldson and Young (Science, 2008). These are animal pharmacology findings, and their extension to human attachment remains an inference rather than a measurement.
Is oxytocin legal to buy in the UK for research?
Oxytocin occupies an unusual position: injectable oxytocin medicines are prescription-only in the UK, so it cannot lawfully be sold or supplied for human administration. It may be purchased strictly as a lyophilised analytical reference material for in-vitro laboratory research, which is the only basis on which UK Peptide Lab supplies it. Purchasers must be 18 or over and confirm research-only use at checkout. It is not supplied for human or veterinary use.
How should oxytocin be handled in the laboratory?
Store lyophilised vials at -20°C, protected from light and moisture. Reconstitute by injecting bacteriostatic water slowly down the inner glass wall and swirling gently until the solution is clear and colourless; never shake or vortex. The disulphide bridge is the oxidation-sensitive site, so minimise headspace, avoid repeated freeze-thaw cycles and keep aliquots single-use. Store the reconstituted solution at 2-8°C and use within 4 weeks.
Where can I buy Oxytocin in the UK for research?
UK Peptide Lab sells Oxytocin 5mg vials of lyophilised powder from UK stock. Orders placed before 3pm on a working day are dispatched the same day by Royal Mail Tracked, and UK delivery is free over £69. It is sold for in-vitro research only, to buyers aged 18 or over.
What is oxytocin peptide used for in research?
Receptor, structural and behavioural research. It is the reference agonist at OXTR (Gimpl and Fahrenholz, Physiol Rev, 2001) and a reference ligand in receptor structure work. Animal models use it in pair bonding (Insel and Hulihan, 1995) and stress research (Grinevich and Neumann, 2021).
Is your Oxytocin third-party tested?
Not yet. The published certificate for batch UKPL-9512 is the supplier's analysis, reporting 98.39% purity by RP-HPLC and 5.11mg measured content against the 5mg label. Independent third-party testing of this batch is in progress, and that report will be published when complete. Every vial label carries the batch number.
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