Oxytocin

Oxytocin has a peculiar place in peptide history. It is the molecule that proved the field worked. In 1953 Vincent du Vigneaud isolated the nonapeptide from posterior pituitary extract, deduced the sequence CYIQNCPLG with a disulfide bridge between the two cysteines, and then synthesised the whole thing in the lab. Two years later he had a Nobel Prize, awarded specifically for the synthesis rather than the discovery, because doing it on a bench was the harder problem. Every research peptide listed on this site descends, methodologically, from that 1953 work.

The molecule and its near-twin

The sequence is Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH2, nine residues with the cyclic ring closed by a disulfide between Cys1 and Cys6 and a glycinamide tail. The closest endogenous analogue is vasopressin, which differs in exactly two positions: a phenylalanine where oxytocin carries isoleucine at residue 3, and an arginine where oxytocin carries leucine at residue 8. Those two substitutions are the entire reason one peptide acts on uterine smooth muscle and central social circuits while the other governs water retention and vasoconstriction. Studies in receptor pharmacology often run the pair side by side because the cross-reactivity at OXTR and the AVPR1a/1b/2 receptors is the whole point of the experiment.

Worth being clear about

The vial we ship is research-grade lyophilised peptide, not Syntocinon or Pitocin. Those are licensed pharmaceutical products manufactured under different specs, packaged in sterile aqueous ampoules, and prescribed for obstetric use under MHRA marketing authorisation. What you are buying here is for in vitro work and rodent-model pharmacology. The molecule is the same; the regulatory pathway, sterility framework, and intended use are not.

Where the research clusters

• Intranasal social cognition work in healthy human volunteers (Heinrichs, Domes and colleagues from the mid-2000s onwards, looking at trust, face recognition, in-group bias)
• Central amygdala and hypothalamic circuitry in rodent models of pair-bonding, including the prairie vole literature originated by Sue Carter and Larry Young
• HPA-axis and cortisol attenuation studies under acute social stress
• Peripheral roles outside the brain: uterine OXTR signalling, milk-ejection reflex, bone remodelling via OTR on osteoblasts, and a growing GI literature

Spec on the vial

Purity on our lots runs at 98 percent or better by reverse-phase HPLC, with mass spec confirming the monoisotopic mass at 1007.4 Da for the oxidised cyclic form. Each vial carries a lot number that matches its Certificate of Analysis. If the lot does not match its CoA on arrival, we refund it. The shipped form is white lyophilised powder under inert gas in a sealed glass vial, with the CoA available on request or already with your order if you flagged it at checkout.

Where it comes from and how it gets to you

Synthesis is contracted to UK and EU peptide manufacturers we have audited rather than to anonymous Asian wholesalers, because oxytocin in particular is a sequence where lazy purification leaves vasopressin and deamidation impurities at levels that confound binding assays. UK orders placed before late afternoon Monday to Thursday dispatch the same day, and about nine in ten arrive within 48 hours. Live chat during UK hours is staffed by people who handle stock, not a script. For ten vials or more, ping support and we will quote bulk rather than running the order through the cart.

Sold strictly for in vitro laboratory research. Not for human or veterinary use. UK 18+.