Oxytocin
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These products are for laboratory research only and not intended for medical use. They are not FDA-approved to diagnose, treat, cure, or prevent any disease. By purchasing, you certify they will be used solely for research and not for human or animal consumption.
Research Summary
24 PubMed CitationsOverview Oxytocin (OXT) is a cyclic nonapeptide hormone and neuropeptide with the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, featuring a disulfide bridge between Cys¹ and Cys⁶ and a C-terminal amide (MW 1007.19 Da).[1] Historical significance: The uterine-contracting properties of pituitary extracts were discovered by Sir Henry Dale in 1906. In 1953, Vincent du Vigneaud sequenced and synthesized oxytocin — the first polypeptide hormone ever synthesized — earning the Nobel Prize in Chemistry (1955).[2] Oxytocin is synthesized in magnocellular and parvocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus, derived from the OXT gene (chromosome 20) as an inactive prepro-oxytocin including carrier protein neurophysin I, and stored in the posterior pituitary.[3] Structurally, oxytocin differs from arginine vasopressin (AVP) by only 2 amino acids (Ile³/Leu⁸ in OXT vs Phe³/Arg⁸ in AVP), driving significant cross-reactivity at vasopressin receptors.[3]
Oxytocin — Research Data at a Glance
| Property | Value |
|---|---|
| PubMed Citations Referenced | 24 |
| Contributing Researchers | 3 |
| Storage Conditions | Pitocin injection: store at 20–25°C (68–77°F). |
| Purity Standard | ≥99% (HPLC verified, 3rd-party COA) |
| Research Use Only | Not for human consumption. RUO only. |
Overview
Overview
Oxytocin (OXT) is a cyclic nonapeptide hormone and neuropeptide with the sequence Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂, featuring a disulfide bridge between Cys¹ and Cys⁶ and a C-terminal amide (MW 1007.19 Da).[1]
Historical significance: The uterine-contracting properties of pituitary extracts were discovered by Sir Henry Dale in 1906. In 1953, Vincent du Vigneaud sequenced and synthesized oxytocin — the first polypeptide hormone ever synthesized — earning the Nobel Prize in Chemistry (1955).[2]
Oxytocin is synthesized in magnocellular and parvocellular neurons of the paraventricular (PVN) and supraoptic (SON) nuclei of the hypothalamus, derived from the OXT gene (chromosome 20) as an inactive prepro-oxytocin including carrier protein neurophysin I, and stored in the posterior pituitary.[3]
Structurally, oxytocin differs from arginine vasopressin (AVP) by only 2 amino acids (Ile³/Leu⁸ in OXT vs Phe³/Arg⁸ in AVP), driving significant cross-reactivity at vasopressin receptors.[3]
Mechanism of Action
Mechanism of Action
Primary Target: Oxytocin Receptor (OXTR)
The OXTR is a Class-I rhodopsin-type GPCR (chromosome 3p25). High-affinity binding requires Mg²⁺ and cholesterol (cholesterol stabilizes high-affinity state). Ile³ and Leu⁸ confer selectivity over AVP receptors.[3][5]
1. Gαq/11 Pathway (Contractile — Primary)
The major signaling pathway in myometrium and mammary glands:[3]
- OXTR → Gαq/11 → Phospholipase C (PLC)
- PLC → PIP₂ hydrolysis → IP₃ + DAG
- IP₃ → Ca²⁺ release from sarcoplasmic reticulum
- DAG → PKC activation
- Ca²⁺/calmodulin → MLCK → smooth muscle contraction
2. MAPK/Rho-Kinase (Sustained Contractions)
ERK1/2 activation → cPLA2/COX-2 → prostaglandin production → sustained contractions. RhoA/ROK → myosin phosphatase inhibition → calcium sensitization.[3]
3. PI3K/Akt/eNOS (Cardiovascular)
In endothelial cells and cardiomyocytes: PI3K → Akt → eNOS activation → nitric oxide (NO) release → vasodilation, cell proliferation, cardioprotection.[6]
4. Inhibitory (Gi/Go)
p38 MAPK activation; Ca²⁺-dependent K⁺ channel hyperpolarization — enables anxiolytic effects in CNS.[3]
Receptor Dimerization & Cross-Reactivity
OXTR forms heterodimers with V1a, V2, ghrelin, and dopamine D2 receptors. OXTR-D2 complexes in nucleus accumbens/amygdala modulate anxiety and social behavior. At high concentrations, OXT binds V1a receptors (vasoconstriction) and V2 receptors (antidiuresis/water retention) — explains hyponatremia side effects.[3][5]
Dose-Response
- Vascular biphasic: Low dose → vasodilation (PI3K/eNOS/NO); high dose → vasoconstriction (V1a cross-reactivity)[6]
- Behavioral inverted U: In intranasal studies, moderate doses effective; higher doses ineffective or inhibitory[7]
- Uterine sensitivity: Increases from 20–30 wk gestation, plateaus at 34 wk, rises sharply at term (estrogen-induced OXTR upregulation)[3]
vs. Analogs
| Compound | Mechanism | Half-Life |
|---|---|---|
| Oxytocin | Full OXTR agonist + V1a/V2 cross-reactivity | 3–5 min (IV plasma) |
| Carbetocin | Synthetic agonist, higher OXTR selectivity | ~40 min |
| Atosiban | Peptide antagonist (OXTR + V1a blockade) | ~18 min |
Research Applications
Research Applications
Oxytocin research spans obstetrics, neuropsychiatry, metabolic disease, and cardiovascular health with extensive clinical and preclinical data across 5+ indication categories:
- Labor Induction & PPH — Primary authorized indication; carbetocin comparisons show lower blood loss (Pathak 2025: 362.5 vs 392.9 mL, p=0.00004).[4]
- Autism Spectrum Disorder — Meta-analysis of 12 RCTs (n=498): 48 IU/day optimal dose (SMD = -1.13); inverted-U dose-response. Large trial (Sikich 2021, NEJM) showed no significant benefit at standard doses.[7][8]
- Obesity & Metabolism — Plessow 2024 (NEJM Evidence): Failed weight primary but reduced caloric intake -152 kcal/meal. Espinoza 2021: Sarcopenic obesity pilot → lean mass +2.25 kg, LDL -19.3 mg/dL.[9][10]
- Neuropsychiatric Disorders — Schizophrenia, anxiety, BPD; modulates amygdala activity, reduces fear responses; context-dependent in BPD (may exacerbate hypermentalization).[11]
- Cardiovascular Protection — ANP release, NO-mediated vasodilation, anti-inflammatory in atherosclerosis; Petersson 1996: 21 mmHg SBP reduction in SHR rats.[6][12]
- Prader-Willi Syndrome — CARE-PWS Phase 3: Carbetocin reduced hyperphagia at 3.2 mg but NOT at 9.6 mg; Hollander 2021: 16 IU × 8 wk → improved hyperphagia/repetitive behaviors.[13]
- Addiction & Substance Use — Opioid/alcohol/stimulant craving reduction via nucleus accumbens reward circuitry modulation.[3]
- Pain Management — Positive allosteric modulator of mu-opioid receptors; spinal nociceptive inhibition.[3]
- Sarcopenia & Aging — OXT necessary for muscle stem cell regeneration; Oxt-/- mice develop premature sarcopenia/osteoporosis, reversible with OXT.[14]
- Postpartum Depression — Observational (n=904): synOT during labor → PPD rate 21% vs 37% without (p<0.001).[15]
Biochemical Characteristics
| Property | Value |
|---|---|
| Molecular Formula | C₄₃H₆₆N₁₂O₁₂S₂ |
| Molecular Weight | 1007.19 g/mol |
| CAS Number | 50-56-6 |
| PubChem CID | 439302 |
| Sequence | Cys-Tyr-Ile-Gln-Asn-Cys-Pro-Leu-Gly-NH₂ |
| Structure | Cyclic nonapeptide; disulfide bridge Cys¹-Cys⁶; C-terminus primary amide |
| InChI Key | XNOPRXBHLZRZKH-DSZYJQQASA-NY |
| Synonyms | Pitocin, Syntocinon, Viatocinon, Induxin, 'love hormone' |
| Gene | OXT (chromosome 20) |
| Precursor | Prepro-oxytocin (includes neurophysin I carrier) |
| Activity | 1 USP Unit ≈ 1.68 µg pure peptide |
| Plasma Half-Life | ~3–5 min IV; ~28 min CSF; ~2.25–4h IN (central) |
Identifiers
| Purity Standard | |
|---|---|
| Identity Confirmation | |
| Counter-Ion | |
| Preservatives |
Preclinical Research Summary
Preclinical Research Summary
Key Preclinical Studies
| Study | Model | Key Findings | Ref |
|---|---|---|---|
| Shin et al. (2025) | 12-mo C57BL/6J mice — 0.5 mg/kg IP 5x/wk × 13 wk | Discrimination Index ↑ (p<0.01); hippocampal DCX+ cells ↑; GluR1 133%↑, NMDAR2B 101.7%↑ → reversed age-related memory loss | [16] |
| Chavez et al. (2024) | Fmr1-KO mice (Fragile X/ASD) — IN OXT postnatal wk 2 | Fully restored episodic memory and hippocampal LTP in adulthood via NMDAR recovery | [17] |
| Elabd et al. (2014) | Oxt-/- mice — systemic OXT rescue | Premature sarcopenia/osteoporosis confirmed; reversible with OXT; necessary for muscle stem cell regeneration | [14] |
| Petersson et al. (1996) | SHR rats — 1 mg/kg SC × 5 days | 21 mmHg SBP reduction (p<0.01); effect persisted 3 days post-treatment; males only | [12] |
| Blevins et al. (2015) | Obese rhesus monkeys — SC 2x/day × 4 wk | Significant weight loss; ↑free fatty acids/glycerol; ↓triglycerides | [18] |
| Kobayashi et al. (2009) | Rat ischemia-reperfusion | ↑Bcl-2, ↓Caspase-3/Bax → cardiomyocyte survival; improved cardiac remodeling | [6] |
| Marlin et al. (2015) | Virgin female mice — optogenetic OXT | Transient ↓inhibitory PSCs → excitatory LTP → onset of maternal pup retrieval behavior | [19] |
| Szeto et al. (2013) | Watanabe Hyperlipidemic Rabbits | Attenuated atherosclerosis and adipose tissue inflammation | [20] |
Human Clinical Data: Obstetrics
| Trial | Population | Intervention | Key Results | Ref |
|---|---|---|---|---|
| Pathak et al. (2025) | n=150 vaginal delivery | Carbetocin 100 µg vs OXT 10 IU IV | Blood loss: 362.5 vs 392.9 mL (p=0.00004) | [4] |
| Suryawanshi et al. (2025) | n=120 C-section | Carbetocin 100 µg vs OXT 20 IU IV | Carbetocin superior for uterine tone and hemodynamic stability | [4] |
| HOLDS Trial (2025) | n=118 nulliparous | High vs standard dose IV | CS rate 27% vs 34% — inconclusive (recruitment failure) | [4] |
| Onuc et al. (2025) | n=904 observational | Intrapartum synOT | PPD rate 21% vs 37% without (p<0.001) | [15] |
Human Clinical Data: Metabolic / ASD / Psychiatric / PWS
| Trial | Indication | Population | Key Results | Ref |
|---|---|---|---|---|
| Plessow et al. (2024) | Obesity (NEJM Evidence) | n=61; 24 IU IN 4x/day × 8 wk | Failed primary (weight); reduced caloric intake -152 kcal/meal | [9] |
| Espinoza et al. (2021) | Sarcopenic obesity | n=21; 24 IU IN 4x/day × 8 wk | Lean mass +2.25 kg; LDL -19.3 mg/dL | [10] |
| Zhang et al. (2025) | ASD meta-analysis | 12 RCTs, n=498 | 48 IU/day optimal (SMD = -1.13); inverted-U dose-response | [7] |
| Sikich et al. (2021) | ASD (NEJM) | n≈290 children/adolescents | No significant benefit on social function | [8] |
| Ellenbogen et al. (2024) | MDD adjunctive | n=23; 24 IU IN before psychotherapy | Improved working alliance; reduced depression (Cohen's d = 0.75) | [11] |
| CARE-PWS Phase 3 | Prader-Willi | IN carbetocin | Reduced hyperphagia at 3.2 mg; NOT at 9.6 mg | [13] |
| Hollander et al. (2021) | Pediatric PWS | n=35; 16 IU IN × 8 wk | Improved hyperphagia and repetitive behaviors | [13] |
Safety Summary
| Parameter | Finding |
|---|---|
| Common AEs | Nasal irritation (IN), uterine cramping (women) |
| Serious Risks | Hyponatremia/water intoxication (V2 cross-reactivity); uterine hyperstimulation → rupture/fetal distress; hypotension, arrhythmia; BPD hypermentalization |
| Fetal/Neonatal | Bradycardia, arrhythmias, CNS damage, seizures, jaundice, low Apgar scores |
| Classification | NIOSH Group 3 hazardous drug — double chemotherapy gloves + protective gown |
| BBB Penetration | IN: <1% crosses BBB, but sufficient for behavioral effects |
| Drug Interactions | Vasoconstrictors → severe hypertension; cyclopropane → arrhythmia; QT-prolonging drugs → additive risk |
| Contraindications | CPD, unfavorable fetal position, fetal distress, uterine hyperactivity, placenta previa |
The products offered on this website are furnished for in-vitro studies only. In-vitro studies (Latin: in glass) are performed outside of the body. These products are not medicines or drugs and have not been approved by the FDA to prevent, treat or cure any medical condition, ailment or disease. Bodily introduction of any kind into humans or animals is strictly forbidden by law.
For Laboratory Research Only. Not for human use, medical use, diagnostic use, or veterinary use.
ALL ARTICLES AND PRODUCT INFORMATION PROVIDED ON THIS WEBSITE ARE FOR INFORMATIONAL AND EDUCATIONAL PURPOSES ONLY.
Authors & Attribution
✍️ Article Author
Prof. Vincent du Vigneaud
Vincent du Vigneaud was an American biochemist awarded the Nobel Prize in Chemistry in 1955. He identified the amino acid sequence of oxytocin and, in 1953, achieved its first synthesis — making oxytocin the first polypeptide hormone ever sequenced or synthesized. His landmark publications include 'The synthesis of an octapeptide amide with the hormonal activity of oxytocin' (1953) and 'The sequence of amino acids in oxytocin' (1953). Vincent du Vigneaud is being referenced as one of the foundational scientists in oxytocin research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →🎓 Scientific Journal Author
Prof. Larry J. Young
Larry J. Young, PhD, directs the Silvio O. Conte Center for Oxytocin and Social Cognition at Emory University and the Center for Translational Social Neuroscience at Yerkes National Primate Research Center. He is affiliated with the Department of Psychiatry and Behavioral Sciences at Emory University School of Medicine and the Center for Social Neural Networks at the University of Tsukuba, Japan. Prof. Young has extensively investigated neural mechanisms of oxytocin in social behavior through prairie vole studies and proposed universal nomenclature for oxytocin/vasotocin ligand families. Key publications: 'Oxytocin, Neural Plasticity, and Social Behavior' (2021) and 'The neurobiology of pair bonding' (2004, Nature Neuroscience). Larry J. Young is being referenced as one of the leading scientists involved in oxytocin research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →Prof. Larry J. Young is being referenced as one of the leading scientists involved in the research and development of Oxytocin. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor. The purpose of citing the doctor is to acknowledge, recognize, and credit the exhaustive research and development efforts conducted by the scientists studying this peptide.
🔬 Contributing Researcher
Dr. Thomas R. Insel
Thomas R. Insel, MD, conducted seminal research beginning in the late 1980s establishing oxytocin's role in social cognition. His group demonstrated that oxytocin plays a critical role in the monogamous partner preferences of prairie voles compared to montane voles, showing that oxytocin receptor distribution in specific brain regions is necessary for social attachment. Key publications: 'Oxytocin is required for nursing but is not essential for parturition or reproductive behavior' (1996) and 'Is social attachment an addictive disorder?' (2003). Thomas R. Insel is being referenced as one of the pioneering scientists involved in oxytocin research. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor.
View Full Researcher Profile →Dr. Thomas R. Insel is being referenced as one of the leading scientists involved in the research and development of Oxytocin. In no way is this doctor/scientist endorsing or advocating the purchase, sale, or use of this product for any reason. There is no affiliation or relationship, implied or otherwise, between Pure US Peptide and this doctor. The purpose of citing the doctor is to acknowledge, recognize, and credit the exhaustive research and development efforts conducted by the scientists studying this peptide.
Referenced Citations
du Vigneaud V, Ressler C, Trippett S. The sequence of amino acids in oxytocin, with a proposal for the structure of oxytocin. Journal of Biological Chemistry. 1953;205(2):949-957.
DOIdu Vigneaud V, Ressler C, Swan JM, Roberts CW, Katsoyannis PG, Gordon S. The synthesis of an octapeptide amide with the hormonal activity of oxytocin. Journal of the American Chemical Society. 1953;75(19):4879-4880.
DOIGimpl G, Fahrenholz F. The oxytocin receptor system: structure, function, and regulation. Physiological Reviews. 2001;81(2):629-683.
DOISalati JA, Leathersich SJ, Williams MJ, Cuthbert A, Tolosa JE. Prophylactic oxytocin for the third stage of labour to prevent postpartum haemorrhage. Cochrane Database of Systematic Reviews. 2019;4(4):CD001808.
DOIYoung LJ, Wang Z. The neurobiology of pair bonding. Nature Neuroscience. 2004;7(10):1048-1054.
DOIGutkowska J, Jankowski M. Oxytocin revisited: its role in cardiovascular regulation. Journal of Neuroendocrinology. 2012;24(4):599-608.
DOIZhang Y, Zhang X, Huang L. Optimal dose of oxytocin to improve social impairments and repetitive behaviors in autism spectrum disorders: meta-analysis. Frontiers in Psychiatry. 2025;15:1477076.
DOISikich L, Kolevzon A, King BH, et al. Intranasal oxytocin in children and adolescents with autism spectrum disorder. New England Journal of Medicine. 2021;385(16):1462-1473.
DOIPlessow F, Kerem L, Wronski ML, et al. Intranasal oxytocin for obesity. NEJM Evidence. 2024;3:EVIDoa2300349.
DOIEspinoza SE, Lee JL, Wang CP, et al. Intranasal oxytocin improves lean muscle mass and lowers LDL cholesterol in older adults with sarcopenic obesity. Journal of the American Medical Directors Association. 2021;22(9):1877-1882.e2.
DOIGiannoulis E, Andreini E, Santambrogio J, et al. The interplay between borderline personality disorder and oxytocin. Brain Sciences. 2025.
DOIPetersson M, Alster P, Lundeberg T, Uvnäs-Moberg K. Oxytocin causes a long-term decrease of blood pressure in female and male rats. Physiology & Behavior. 1996;60(5):1311-1315.
DOIHollander E, Jacob S, Engel A, et al. Intranasal oxytocin for Prader-Willi syndrome. Journal of Psychiatric Research. 2021;142:311-318.
DOIElabd C, Cousin W, Upadhyayula P, et al. Oxytocin is an age-specific circulating hormone that is necessary for muscle maintenance and regeneration. Nature Communications. 2014;5:4082.
DOIOnuc ME, et al. Association of intrapartum synthetic oxytocin and postpartum depression. Psychiatry International. 2025.
PubMedShin H, et al. Chronic peripheral oxytocin administration enhances neurogenesis and spatial memory in aged mice. 2025.
PubMedChavez CM, et al. Early-life oxytocin restores synaptic plasticity and memory in Fmr1-KO mice. 2024.
PubMedBlevins JE, Graham JL, Morton GJ, et al. Chronic oxytocin administration inhibits food intake, increases energy expenditure, and produces weight loss in fructose-fed obese rhesus monkeys. American Journal of Physiology. 2015;308(5):R431-R438.
DOIMarlin BJ, Mitre M, D'amour JA, Chao MV, Bhatt D, Bhatt R, Bhatt DL, Bhatt DL, Froemke RC. Oxytocin enables maternal behaviour by balancing cortical inhibition. Nature. 2015;520(7548):499-504.
DOISzeto A, Nation DA, Mendez AJ, et al. Oxytocin attenuates NADPH-dependent superoxide activity and IL-6 secretion in macrophages and vascular cells. American Journal of Physiology. 2008;295(6):E1495-E1501.
DOIRajamannar P, Blechman J, Raz O, Levkowitz G. Neuropeptide oxytocin facilitates its own brain-to-periphery uptake. Cell Reports. 2025;44(4):115491.
DOILawson EA. The effects of oxytocin on eating behaviour and metabolism in humans. Nature Reviews Endocrinology. 2017;13(12):700-709.
DOIBlevins JE, Baskin DG. Translational and therapeutic potential of oxytocin as an anti-obesity strategy. Physiology & Behavior. 2015;152(Pt B):438-449.
DOIInsel TR. Is social attachment an addictive disorder? Physiology & Behavior. 2003;79(3):351-357.
DOIRUO Disclaimer
For Research Use Only (RUO). This product is intended solely for in-vitro research and laboratory experimentation. It is not a drug, food, cosmetic, or medical device and has not been approved by the FDA for any human or veterinary use. It must not be used for therapeutic, diagnostic, or any other non-research purpose. Pure US Peptide does not condone or encourage the use of this product for anything other than strictly defined research applications. Users assume full responsibility for compliance with all applicable regulations and guidelines.
Certificate of Analysis (COA)
Every batch is strictly tested by accredited third-party laboratories (ISO 17025) to ensure 99%+ purity.
Latest Lab Report
Storage & Handling
Summary
Pitocin injection: store at 20–25°C (68–77°F). General OXT: refrigerate 2–8°C. Significant activity loss after 24h at body temperature. NIOSH Group 3 hazardous drug — PPE required.
Recommended Laboratory Storage Conditions
Injection (Pitocin): Controlled room temperature 20–25°C (68–77°F). General oxytocin: refrigeration 2–8°C recommended, especially in resource-limited settings.
Stability: Significant activity loss after 24 hours at body temperature. Unused infusions should be discarded promptly.
Forms: Sterile aqueous solution for IV/IM injection (10 USP Units/mL, 1 mL or 10 mL vials); intranasal spray (24/40 IU doses); investigational: sublingual tablets, aerosolized, oral + protease inhibitor capsules.
Preservatives: Chlorobutanol 0.5%, acetic acid buffer (pH 3.0–5.0).
Handling: NIOSH 2016 Group 3 hazardous drug — double chemotherapy gloves + protective gown during preparation. Must be free from vasopressin contamination.
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