Oxytocin Peptide – Overview, Research, Safety Profile

Oxytocin is a naturally occurring cyclic peptide hormone composed of nine amino acids. It mainly acts as a neurotransmitter in the brain and is secreted by the pituitary gland.⁽¹⁾  The synthetic form of Oxytocin, called Recombinant Oxytocin, is also a cyclic nonapeptide analogous to the naturally occurring peptide. ⁽²⁾

Synthesized by the hypothalamus, the compound is secreted and stored in the posterior pituitary gland and is later released in the body upon hormonal stimulation.⁽³⁾

Oxytocin peptide appears to work through a positive feedback mechanism. This means that the hormone peptide’s initial secretion may further release the peptide in higher concentrations and with higher intensity. Both synthetic and natural forms of the peptide appear to work through the exact mechanism causing a similar response in the female reproductive system.

Research in the Oxytocin Peptide

Uterine contractions and Labor induction

Oxytocin is derived from a Greek word where ‘Oxus’ means swift, and ‘tokos’ means childbirth. As indicated by its name, the peptide helps make childbirth faster and smoother.

“Oxytocin is indicated and approved by the FDA for two specific time frames in the obstetric world: antepartum and postpartum. In the antepartum period, exogenous oxytocin is FDA-approved for strengthening uterine contractions with the aim of successful vaginal delivery of the fetus. There are three situations during the antepartum period, which indicate the use of oxytocin. These include mothers with preeclampsia, maternal diabetes, premature rupture of the membranes, mothers with inactive uteri that require stimulation into labor, and mothers with inevitable or incomplete abortions in their second trimester. Postpartum, oxytocin is FDA-approved when it is time to deliver the placenta during the third stage of labor and control postpartum hemorrhage.” ⁽³⁾

Once in the system, the peptide appears to bind with the G-protein coupled receptors found in the uterus membrane, potentially increasing intracellular calcium levels. This calcium secretion then causes uterine contractions. Once the uterine contractions begin, it may stimulate the release of the compound, leading to higher frequency and intensity of the contractions via a positive feedback mechanism.

A clinical study ⁽⁴⁾ was conducted to determine the rate of cesarean delivery in women after discontinuing the compound administration once active labor began (5 cm cervical dilation) compared to women where Oxytocin was administered until the maintenance level as determined in the clinical trial study protocol. The study suggested that the percentage of cesarian deliveries was much higher if Oxytocin administration was stopped partway versus those who were given the peptide until birth. This result suggests that Oxytocin positively induces labor.

Breastfeeding

The peptide can potentially cause contraction of the myoepithelial cells found in the alveolar ducts of the female breasts. These contractions stimulate milk ejection from these alveolar ducts into the larger sinuses, thereby expelling milk. The positive feedback mechanism may work here, and initial milk expulsion may stimulate further peptide release and continuous milk release. ⁽³⁾

An study was conducted⁽⁵⁾ and found that of the participants who were successfully breastfeeding, 27% were supplemented with doses of Oxytocin, whereas only 14% were not. While further research is needed, the evaluation strongly suggests that Oxytocin has the potential to positively affect lactation and help to increase breastfeeding duration.

Some additional properties under research:

• Oxytocin may possess vasodilatory properties, which can help improve cardiac function and tone in the heart muscles. A study⁽⁶⁾ suggested that Oxytocin may help regulate the blood pressure and heart rate in pregnant women upon administration.
• Oxytocin has been suggested to have a positive effect on the social behavior abilities of autistic patients.⁽⁷⁾ Autism is a psychiatric disorder related to poor brain development impacting how people socialize and communicate with others. This discovery implies that this peptide can potentially be used in psychiatric treatment.
• Another neurological ailment in which Oxytocin has shown positive effects is Schizophrenia. Schizophrenia is a chronic neurological disorder characterized by hallucinations, impaired speech, and lack of motivation. Schizophrenia is mainly caused due to an imbalance in Oxytocin levels; therefore, administering supplemental dosages of the peptide may help maintain the brain’s Oxytocin at equilibrate levels.⁽⁸⁾
• It also carries potential to treat patients suffering from obsessive-compulsive disorder (OCD). However, in research studies investigating this potential observed increased cases of memory disturbances and instances where the patients showed reduced sodium levels in blood plasma and decreased osmolality. Therefore, a clear understanding is yet to be established, and additional studies are to still in process to show if the peptide can help treat OCD patients effectively.

Oxytocin Safety Profile

The common side effects reported by researchers in studies of Oxytocin peptides are: ⁽³⁾

• Irritation and redness at the site of administration
• Nausea
• Vomiting
• Stomach ache
• Appetite loss
• Increased contractions
• Breathing difficulties
• Abnormal bleeding

Serious adverse effects of the peptide may include:

• Irregular heart rhythm
• Seizures
• Hallucinations, delusions
• Elevated blood pressure
• Blurred vision

There can be certain contradictions towards Oxytocin primarily due to hypersensitivity towards the peptide or a synthetic version of it. The following conditions may lead to contradictions in administering the peptide: ⁽³⁾

• When the fetal position is abnormal
• Cervical cancer
• Herpes
• Women with pelvises too small to handle standard delivery
• Women with a uterus that is highly active and tonic
• High blood pressure⁽⁹⁾
• Placental previa (a condition where the placenta blocks the uterine neck)⁽⁹⁾
• Uterus surgery / cervical surgery⁽⁹⁾

It is critical to monitor the fluid levels of the patients after Oxytocin administration.⁽⁷⁾ Improper dosing of Oxytocin may cause severe toxic reactions in the patients, such as arrhythmia and ischemia, and high doses can also lead to spasms and even uterine rupture.

In 2012, a retrospective study ⁽⁶⁾ was conducted where the hemoglobin levels of the women treated with this compound during labor were examined. Women treated with higher Oxytocin doses led to extremely high blood loss compared to women either treated with moderate Oxytocin levels or not treated with the peptide. This suggests that improper dosing of the peptide hormone can lead to severe adverse effects.

Conclusion

Oxytocin is a nonapeptide hormone that appears to primarily exert its facilitating potential on the female reproductive system. Available in both endogenous (natural) and exogenous (synthetic) forms, Oxytocin primarily works via a positive feedback mechanism.

The peptide’s primary properties are suggested to stimulate uterine muscle contraction (used to induce labor) and increase milk ejection (used to induce lactation). Besides, it also possesses vasodilatory potential and may play a vital role in monitoring psychiatric disorders.

Since its discovery over 100 years ago, Oxytocin has been rigorously studied for labor induction and postpartum use. However, further peptide studies are still underway, especially to explore its role in potentially treating human psychiatric disorders.

This peptide is strictly available for research and laboratory settings, not personal use.

References:

1. National Center for Biotechnology Information. “PubChem Compound Summary for CID 439302, Oxytocin” PubChem, https://pubchem.ncbi.nlm.nih.gov/compound/Oxytocin
2. Recombinant Oxytocin (Code C724). https://ncit.nci.nih.gov/ncitbrowser/ConceptReport.jsp?dictionary=NCI_Thesaurus&ns=NCI_Thesaurus&code=C724
3. Osilla EV, Sharma S. Oxytocin. [Updated 2021 Jul 27]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. https://www.ncbi.nlm.nih.gov/books/NBK507848/
4. Induction of Labor with Oxytocin: When Should Oxytocin be held? https://clinicaltrials.gov/ct2/show/results/NCT00957593
5. Gomes M, Trocadero V, Carlos-Alves M, Arteiro D, Pinheiro P. Intrapartum synthetic oxytocin and breastfeeding: a retrospective cohort study. J Obstet Gynaecol. 2018 Aug;38(6):745-749. Epub 2018 Mar 9. https://pubmed.ncbi.nlm.nih.gov/29523035/
6. Rabinow, S., Hjorth, U., Schönbeck, S. et al. Effects of Oxytocin and anesthesia on vascular tone in pregnant women: a randomized, double-blind placebo-controlled study using non-invasive pulse wave analysis. BMC Pregnancy Childbirth 18, 453 (2018). https://bmcpregnancychildbirth.biomedcentral.com/articles/10.1186
7. Cochran, D. M., Fallon, D., Hill, M., & Frazier, J. A. (2013). The role of Oxytocin in psychiatric disorders: a review of biological and therapeutic research findings. Harvard review of psychiatry, 21(5), 219–247. https://doi.org/10.1097/HRP.0b013e3182a75b7d
8. Guastella AJ, Einfeld SL, Gray KM, Rinehart NJ, Tonge BJ, Lambert TJ, Hickie IB. Intranasal Oxytocin improves emotion recognition for youth with autism spectrum disorders. Biol Psychiatry. 2010 Apr 1;67(7):692-4. https://pubmed.ncbi.nlm.nih.gov/19897177/
9. Oxytocin Injection. https://medlineplus.gov/druginfo/meds/a682685.html
10. Cochran, D. M., Fallon, D., Hill, M., & Frazier, J. A. (2013). The role of Oxytocin in psychiatric disorders: a review of biological and therapeutic research findings. Harvard review of psychiatry, 21(5), 219–247. https://doi.org/10.1097/HRP.0b013e3182a75b7d

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