In a recent systematic review published in Current Issues in Molecular Biology, researchers from Portugal examined and discussed the role of oxytocin (OT) in polycystic ovary syndrome (PCOS), its association with PCOS symptoms, and the effect of OT administration.
They found that PCOS is associated with reduced serum OT levels, and alterations in OT levels are linked to fertility issues and body weight, suggesting a potential role of OT dysfunction in the development of PCOS.
Study: The Role of Oxytocin in Polycystic Ovary Syndrome: A Systematic Review. Image Credit: MMD Creative/Shutterstock.com
Background
PCOS is a complex and prevalent endocrine disorder in women of reproductive age that affects their quality of life. It is characterized by polycystic ovaries, androgen excess, and ovulatory dysfunction, often leading to infertility and various metabolic, reproductive, and psychological issues.
PCOS is linked to high levels of androgen and abnormal LH/FSH (luteinizing hormone/ follicle-stimulating hormone) ratios, contributing to anovulatory infertility and increased risks during pregnancy.
Biochemically, OT is a nine-amino acid-long peptide involved in cognitive, emotional, and reproductive functions. While it is generated in the hypothalamus and secreted by the posterior pituitary gland, OT receptors (OXTR) are found in various body parts, including the ovaries and prostate gland.
OT is vital for various reproductive and behavioral functions in humans, including pregnancy, parturition, breastfeeding, bonding, prosocial behavior, decision-making, physical activity, and orgasm.
Previous studies suggest that OT levels are lower in women with PCOS, potentially impacting mood and weight. Animal studies indicate OT deficiency can potentially lead to obesity, and OT administration may reduce weight and enhance muscle tone.
Despite these findings, the exact role of OT in PCOS remains unclear. In the present systematic review, researchers aimed to clarify OT's role in PCOS by examining all the relevant animal and human studies.
Specifically, it focused on (i) identifying potential alterations in basal plasma OT levels in PCOS, (ii) understanding how changes in OT levels might relate to PCOS symptoms, and (iii) investigating the effects of OT administration on PCOS.
About the study
Databases, including PubMed, Scopus, and Web of Science, were thoroughly searched to identify relevant studies. The review involved eight studies, including experimental studies, randomized clinical trials, clinical pilot studies, case-control studies, and population genetics studies.
Five of the included studies were conducted on humans (n = 609 women), while three were conducted on animals. It excluded studies on other endocrine diseases, male studies, reviews, and meta-analyses.
Results and discussion
Cohen’s kappa value was found to be 0.742, indicating significant agreement between the two individual reviewers. The human studies primarily explored the relationship between OT administration and fertility.
Two clinical trials found that intranasal OT did not improve fertility in PCOS patients, possibly due to inadequate dosing or administration methods.
These studies did not measure blood or salivary OT levels. One study found lower OT levels in PCOS patients compared to non-PCOS controls and linked these lower levels to hormonal imbalances in the hypothalamic-pituitary–ovarian (HPO) axis.
A case-control study also associated higher OT levels with improved pregnancy rates in PCOS women. One genetic study examined the gene polymorphisms in OXTR in PCOS patients and found five variants linked to PCOS, suggesting a genetic influence on OXTR expression.
The animal studies used rat models to assess the effects of OT on metabolic disorders and uterine function. One study found that OT administration regulated uterine contractions in PCOS rats, while another reported that acute OT administration could reduce body weight and food intake in PCOS rats.
Chronic OT administration was found to decrease food intake and body weight in both PCOS and control rats. Another study found that OT administration reduced body weight, visceral fat, and adipocyte size in a dihydrotestosterone (DHT)-induced rat PCOS model.
Overall, these findings suggest that OT may influence the metabolic and reproductive functions in PCOS, but further research is warranted to understand its therapeutic potential.
Further, the review highlighted gaps in the current research in the field, such as the need for studies assessing the impact of OT on prosocial behavior, couple relationships, and sexual satisfaction in PCOS.
Different dosage regimens and patterns of OT administration were also found to be insufficiently studied, highlighting the need for further research.
Conclusion
In conclusion, the present review comprehensively examined the studies exploring the effect of OT levels or OT administration on PCOS. Most studies emphasized OT's role in fertility issues, with only one study linking higher OT levels to increased pregnancy rates.
Consistently, basal OT levels were found to be reduced in PCOS women, suggesting that low OT, alongside low FSH levels, contributes to anovulation in PCOS.
Additionally, potential molecular mechanisms involving altered OXTRs and genetic variants in PCOS were discussed. These insights are crucial for potentially developing targeted treatments and improving the quality of life for women with PCOS in the future.
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