Oxytocin

Oxytocin research peptide in Thailand

Oxytocin is a nine-amino-acid cyclic neuropeptide, produced in the hypothalamus and released from the posterior pituitary, studied in reproductive physiology, neuroendocrine signalling, stress reactivity, and social-cognition research. It is one of the most thoroughly characterised peptides in the literature — its receptor, structure, and peripheral physiology have been mapped in detail, and intranasal administration has become a large (and heavily debated) experimental field in its own right.

This listing is for laboratory research use only. Oxytocin is a licensed obstetric medicine in many countries; the material sold here is research-grade reagent, not a medicine, and is not supplied for human or veterinary use.

Quick facts

Product

Oxytocin (lyophilised powder)

CAS

50-56-6

Molecular weight

~1007.2 g/mol

Related peptide

Vasopressin — differs at only two residues, which is why receptor cross-reactivity is a standing methodological issue

Intended use

laboratory research use only

How oxytocin works

Oxytocin acts through the oxytocin receptor, a class I G protein-coupled receptor that couples primarily to Gq/11 and drives phospholipase C activation, IP3 generation, and intracellular calcium release. In peripheral tissue that pathway underlies the two classical physiological effects — uterine smooth-muscle contraction and milk ejection from mammary myoepithelial cells. Receptor density is not fixed: it is strongly modulated by oestrogen and rises dramatically in the uterus toward term, which is one reason oxytocin physiology is studied as a hormone-regulated receptor system rather than a simple ligand story (Gimpl & Fahrenholz, Physiol Rev, 2001).

Centrally, oxytocin is released within the brain by hypothalamic neurons projecting to regions including the amygdala, nucleus accumbens, and brainstem, where it modulates stress and social-processing circuits. The central and peripheral pools are only loosely coupled, and the extent to which intranasally administered oxytocin reaches brain targets at behaviourally relevant concentrations remains genuinely contested — a caveat researchers should carry into any study design that assumes central engagement (Leng & Ludwig, Biol Psychiatry, 2016).

Key research findings

• In a double-blind experiment using a trust game with real monetary stakes, intranasal oxytocin increased transfers to a trustee relative to placebo, with no comparable effect on a non-social risk task (Kosfeld, Nature, 2005).
• In a placebo-controlled study combining intranasal oxytocin with social support before the Trier Social Stress Test, the combination was associated with the lowest cortisol response and reduced subjective anxiety among the conditions tested (Heinrichs, Biol Psychiatry, 2003).
• A critical review of the trust literature found that effects were not reliably reproduced across studies and concluded the evidence that intranasal oxytocin increases trust in humans is weak, highlighting small samples and publication bias (Nave, Perspect Psychol Sci, 2015).

Reproducibility is the defining methodological problem in this field. Analyses of intranasal oxytocin studies have documented systematically underpowered designs, flexible analysis with subgroup and interaction effects, and effect sizes that shrink on replication (Walum, Biol Psychiatry, 2016). Treat single positive social-cognition findings as hypotheses, not settled results.

Research applications

• Oxytocin receptor pharmacology, binding, and Gq/calcium-signalling assays
• Uterine and mammary smooth-muscle contractility models
• Neuroendocrine and HPA-axis stress-reactivity research
• Social cognition and social-behaviour paradigms in animal and human study designs
• Receptor-selectivity work distinguishing oxytocin from vasopressin signalling
• Peptide stability, delivery-route, and pharmacokinetic method development
• Replication and methodological studies addressing the field's power and reliability problems

Dosing in the literature

Oxytocin is dosed in international units throughout the published literature; the mcg figures above use the USP conversion of 1 IU to about 1.67 mcg, so that this page and the calculator work in the same units as every other compound. Behavioural testing in these paradigms usually begins ~30–45 minutes after administration. The 24 IU single intranasal dose (about 40 mcg) became the field's de facto convention rather than a dose-optimised choice, and reviews have specifically flagged the lack of dose-response characterisation as a weakness (Quintana, Mol Psychiatry, 2021). This is a summary of parameters as reported in published research, not administration guidance. To model concentrations for a defined protocol, use the oxytocin peptide calculator.

Reconstitution & storage

Solvent

Bacteriostatic water — standard for lyophilised research peptides

Mixing

Add solvent down the vial wall and swirl gently until dissolved; do not shake

Storage

Refrigerated (2–8 °C) after reconstitution, in common laboratory practice

Use within

A few weeks once reconstituted

Freeze / light

Keep lyophilised powder frozen or cold, sealed, and protected from light

Handling note

A disulfide-bridged cyclic peptide — avoid repeated freeze-thaw cycles and reducing conditions

Standard laboratory practice for lyophilised peptides applies, using sterile technique. In Thailand's heat and humidity, minimise time at ambient temperature during storage and courier handling, since thermal cycling is the main practical threat to peptide integrity here.

Selected research

• The oxytocin receptor system: structure, function, and regulation — Physiol Rev, 2001 (review)
• Oxytocin increases trust in humans — Nature, 2005
• Does oxytocin increase trust in humans? A critical review of research — Perspect Psychol Sci, 2015
• Intranasal oxytocin: myths and delusions — Biol Psychiatry, 2016
• Statistical and methodological considerations for the interpretation of intranasal oxytocin studies — Biol Psychiatry, 2016
• Browse all indexed intranasal oxytocin literature on PubMed

Related compounds

• Selank — an anxiolytic peptide studied in stress and anxiety-behaviour models, a common comparator when oxytocin is examined for stress-axis effects.
• Semax — an ACTH(4-10) analogue studied in neuroprotection and cognition research, another neuropeptide with a substantial intranasal-administration literature.
• Pinealon — a short peptide studied in neuronal and neuroendocrine research contexts.
• Bacteriostatic water — the standard diluent used to reconstitute lyophilised research peptides.

See also: more neuroendocrine signalling compounds.

Oxytocin FAQ

Compliance note

Oxytocin is supplied for laboratory research use only. It is not for human or veterinary use, and it is not intended to diagnose, treat, cure, or prevent any disease. All findings referenced above are the results of specific published studies, not claims about this product.