Oxytocin: Mechanism of Action
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Comprar peptídeo Oxytocin 10mgMecanismo de Acao
Primary Target: Oxytocin Receptor (OXTR)
The OXTR is a Class-I rhodopsin-type GPCR (chromosome 3p25). High-affinity binding requer Mg²⁺ and cholesterol (cholesterol stabilizes high-affinity state). Ile³ and Leu⁸ confer selectivity over AVP receptors.[3][5]
1. Gαq/11 Pathway (Contractile — Primary)
O(a) principal via de sinalizacao in myometrium and mammary glands:[3]
- OXTR → Gαq/11 → Phospholipase C (PLC)
- PLC → PIP₂ hidrolise → IP₃ + DAG
- IP₃ → Ca²⁺ release from sarcoplasmic reticulum
- DAG → PKC ativacao
- Ca²⁺/calmodulin → MLCK → musculo liso contraction
2. MAPK/Rho-Kinase (Sustained Contractions)
ERK1/2 ativacao → cPLA2/COX-2 → prostaglandin production → sustained contractions. RhoA/ROK → myosin phosphatase inibicao → calcium sensibilizacao.[3]
3. PI3K/Akt/eNOS (Cardiovascular)
In celulas endoteliais and cardiomiocitos: PI3K → Akt → eNOS ativacao → nitric oxide (NO) release → vasodilatacao, proliferacao celular, cardioprotecao.[6]
4. Inhibitory (Gi/Go)
p38 MAPK ativacao; 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 alto(a) concentrations, OXT binds V1a receptors (vasoconstricao) and V2 receptors (antidiuresis/water retention) — relevant to reported hyponatremia.[3][5]
Dose-Response
- Vascular biphasic: Low dose → vasodilatacao (PI3K/eNOS/NO); alto(a) dose → vasoconstricao (V1a cross-reactivity)[6]
- Behavioral inverted U: In behavioral studies, intermediate concentrations effective; higher concentrations ineffective or inhibitory[7]
- Uterine sensitivity: Increases from 20–30 wk gestation, plateaus at 34 wk, rises sharply at term (estrogen-induziu OXTR upregulacao)[3]
vs. Analogs
| Compound | Mecanismo | 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 |
“Resumo da Pesquisa Pre-clinica Key Preclinical Studies EstudoModeloPrincipais AchadosRef Shin et al.”
Referencias
- du Vigneaud V, Ressler C, Trippett S. The sequence of aminoacidos in oxytocin, with a proposal for a estrutura of oxytocin. Journal of Biological Chemistry. 1953;205(2):949-957.
- du Vigneaud V, Ressler C, Swan JM, Roberts CW, Katsoyannis PG, Gordon S. The synthesis of an octapeptide amide com o(a) hormonal activity of oxytocin. Journal do(a) American Chemical Society. 1953;75(19):4879-4880.
- Gimpl G, Fahrenholz F. The oxytocin receptor system: structure, function, and regulacao. Physiological Reviews. 2001;81(2):629-683.
- Salati JA, Leathersich SJ, Williams MJ, Cuthbert A, Tolosa JE. Cochrane Database of Systematic Reviews. 2019;4(4):CD001808.
- Young LJ, Wang Z. The neurobiology of pair bonding. Nature Neuroscience. 2004;7(10):1048-1054.
- Gutkowska J, Jankowski M. Oxytocin revisited: its role in cardiovascular regulacao. Journal of Neuroendocrinology. 2012;24(4):599-608.
- Zhang Y, Zhang X, Huang L. Frontiers in Psychiatry. 2025;15:1477076.
- Sikich L, Kolevzon A, King BH, et al. New England Journal of Medicine. 2021;385(16):1462-1473.
- Plessow F, Kerem L, Wronski ML, et al. NEJM Evidence. 2024;3:EVIDoa2300349.
- Espinoza SE, Lee JL, Wang CP, et al. Journal do(a) American Medical Directors Association. 2021;22(9):1877-1882.e2.
- Giannoulis E, Andreini E, Santambrogio J, et al. The interplay between borderline personality disorder and oxytocin. Brain Sciences. 2025.
- Petersson M, Alster P, Lundeberg T, Uvnäs-Moberg K. Oxytocin causes a longo prazo decrease of pressao arterial in female and male rats. Physiology & Behavior. 1996;60(5):1311-1315.
- Hollander E, Jacob S, Engel A, et al. Journal of Psychiatric Research. 2021;142:311-318.
- Elabd C, Cousin W, Upadhyayula P, et al. Oxytocin e um(a) age-specific circulating hormone que is necessario(a) para muscle maintenance and regeneration. Nature Communications. 2014;5:4082.
- Onuc ME, et al. Psychiatry International. 2025.
- Shin H, et al. Chronic periferico(a) oxytocin administration aprimora neurogenese and spatial memory in camundongos idosos. 2025.
- Chavez CM, et al. Early-life oxytocin restaura sinaptico(a) plasticity and memory in Fmr1-KO mice. 2024.
- Blevins JE, Graham JL, Morton GJ, et al. American Journal of Physiology. 2015;308(5):R431-R438.
- Marlin 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 inibicao. Nature. 2015;520(7548):499-504.
- Szeto A, Nation DA, Mendez AJ, et al. Oxytocin atenua NADPH-dependent superoxide activity and IL-6 secretion in macrofagos and vascular cells. American Journal of Physiology. 2008;295(6):E1495-E1501.
- Rajamannar P, Blechman J, Raz O, Levkowitz G. Neuropeptide oxytocin facilita its own brain-to-periphery uptake. Cell Reports. 2025;44(4):115491.
- Lawson EA. Nature Reviews Endocrinology. 2017;13(12):700-709.
- Blevins JE, Baskin DG. Physiology & Behavior. 2015;152(Pt B):438-449.
- Insel TR. Is social attachment an addictive disorder? Physiology & Behavior. 2003;79(3):351-357.
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