Oxytocin improves cytological and histological profiles of vaginal atrophy in postmenopausal women

The physiology and pharmacology of oxytocin in labor and in the peripartum period

Oxytocin is a reproductive hormone implicated in the process of parturition and widely used during labor. Oxytocin is produced within the supraoptic nucleus and paraventricular nucleus of the hypothalamus and released from the posterior pituitary lobe into the circulation. Oxytocin is released in pulses with increasing frequency and amplitude in the first and second stages of labor, with a few pulses released in the third stage of labor. During labor, the fetus exerts pressure on the cervix of the uterus, which activates a feedforward reflex-the Ferguson reflex-which releases oxytocin. When myometrial contractions activate sympathetic nerves, it decreases oxytocin release. When oxytocin binds to specific myometrial oxytocin receptors, it induces myometrial contractions. High levels of circulating estrogen at term make the receptors more sensitive. In addition, oxytocin stimulates prostaglandin synthesis and release in the decidua and chorioamniotic membranes by activating a specific type of oxytocin receptor. Prostaglandins contribute to cervical ripening and uterine contractility in labor. The oxytocin system in the brain has been implicated in decreasing maternal levels of fear, pain, and stress, and oxytocin release and function during labor are stimulated by a social support. Moreover, studies suggest, but have not yet proven, that labor may be associated with long-term, behavioral and physiological adaptations in the mother and infant, possibly involving epigenetic modulation of oxytocin production and release and the oxytocin receptor. In addition, infusions of synthetic oxytocin are used to induce and augment labor. Oxytocin may be administered according to different dose regimens at increasing rates from 1 to 3 mIU/min to a maximal rate of 36 mIU/min at 15- to 40-minute intervals. The total amount of synthetic oxytocin given during labor can be 5 to 10 IU, but lower and higher amounts of oxytocin may also be given. High-dose infusions of oxytocin may shorten the duration of labor by up to 2 hours compared with no infusion of oxytocin; however, it does not lower the frequency of cesarean delivery. When synthetic oxytocin is administered, the plasma concentration of oxytocin increases in a dose-dependent way: at infusion rates of 20 to 30 mIU/min, plasma oxytocin concentration increases approximately 2- to 3-fold above the basal level. Synthetic oxytocin administered at recommended dose levels is not likely to cross the placenta or maternal blood-brain barrier. Synthetic oxytocin should be administered with caution as high levels may induce tachystole and uterine overstimulation, with potentially negative consequences for the fetus and possibly the mother. Of note, 5 to 10 IU of synthetic oxytocin is often routinely given as an intravenous or intramuscular bolus administration after delivery to induce uterine contractility, which, in turn, induces uterine separation of the placenta and prevents postpartum hemorrhage. Furthermore, it promotes the expulsion of the placenta.

The efficacy of oxytocin gel in postmenopausal women with vaginal atrophy: an updated systematic review and meta-analysis

BACKGROUND

Genitourinary syndrome of menopause (GSM) is a common and disturbing issue in the postmenopausal period. Unlike vasomotor symptoms, it has a progressive trend. Our study aims to evaluate the efficacy and safety of oxytocin gel versus placebo gel in postmenopausal women with GSM.

METHODS

A systematic review and meta-analysis synthesizing randomized controlled trials (RCTs) from Web of Science, SCOPUS, PubMed, and Cochrane Central Register of Controlled Trials databases on January 18, 2023. Keywords such as "oxytocin," "intravaginal," "vaginal," "atrophic," and "atrophy" were used. We used Review Manager (RevMan) version 5.4 in our analysis. We used the risk ratio (RR) for dichotomous outcomes and the mean difference (MD) for continuous outcomes; both were presented with the corresponding 95% confidence interval (CI) and were calculated with the Mantel-Haenszel or inverse variance statistical method. Cochrane's Q test and the I2 statistic were used as measures of statistical inconsistency and heterogeneity. The Cochrane Risk of Bias Tool for RCTs was used for the quality assessment of the included studies.

RESULTS

Seven studies with 631 patients were included. Regarding the maturation index, there was a statistically insignificant increase in the oxytocin arm (MD = 12.34, 95% CI (-12.52-37.19), P = 0.33). Clinically assessed vaginal atrophy showed a statistically significant reduction in the oxytocin group (RR = 0.32, 95% CI (0.23 - 0.10), P < 0.00001). For dyspareunia, vaginal pH, and histological evaluation of vaginal atrophy, there was a statistically insignificant difference between the two groups (RR = 1.02, 95% CI (0.82-1.27), P = 0.84), (MD = -0.74, 95% CI (-1.58-0.10), P = 0.08), and (MD = -0.38, 95% CI (-0.82-0.06), P = 0.09), respectively. There was no significant difference in the safety profile between the two groups as measured by endometrial thickness (MD = 0.00, 95% CI (-0.23-0.23), P = 0.99).

CONCLUSIONS

Although oxytocin has been proposed as a viable alternative to estrogen in the treatment of GSM, our findings show the opposite. Larger, high-quality RCTs are needed to confirm or refute our results.

TRIAL REGISTRATION

PROSPERO registration number CRD42022334357.

Effect of topical oxytocin gel on vaginal mucosa in postmenopausal Egyptian women: a clinical randomized trial

BACKGROUND

Vaginal atrophy is common after menopause and is often linked to sexual dysfunction, particularly dyspareunia.

AIM

The study aimed to investigate the effect of intravaginally applied oxytocin on expressions of vaginal atrophy.

METHODS

Fifty postmenopausal women aged 47 to 66 years with vaginal atrophy participated in this double-blinded placebo-controlled study. The women were randomized to intravaginal treatment with either gel with 600 IU/mL of oxytocin (oxytocin group) or gel alone (control group) once daily for 2 weeks. The gel consisted of hypromellose, pH 3.8 (Vagovital).

OUTCOMES

The color of the vaginal mucosa, the vaginal pH, and the cytology of vaginal epithelial cells were investigated before and after treatment.

RESULTS

The color of the vaginal mucosa shifted from pale to red in all 25 patients treated with oxytocin but only in 4 patients in the control group (P < .001). There was a significant decrease in intravaginal pH in the oxytocin group and the control group, with the delta value being significantly greater in the oxytocin group than in the control group (P < .001). The vaginal maturation index increased significantly (P < .001) in the oxytocin group but not in the control group.

CLINICAL IMPLICATIONS

Topical oxytocin gel offers an effective solution to the sexual dysfunction that is related to vaginal atrophy after menopause.

STRENGTHS AND LIMITATIONS

Strengths include studying different outcomes of applying the oxytocin gel for vaginal atrophy. Limitations include the small-scale population with a relatively short duration of treatment (2 weeks).

CONCLUSION

Intravaginal treatment with a gel containing 600 IU/mL of oxytocin effectively counteracts physical expressions of vaginal atrophy.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT05275270; https://clinicaltrials.gov/ct2/show/NCT05275270).

Ultrasonographic measurement of vaginal thickness: Relation to menopausal status and genitourinary syndrome of menopause

OBJECTIVE

To compare the total vaginal wall thickness (TVT) and total mucosal thickness (TMT) measurements of premenopausal and postmenopausal women measured by ultrasonography and to determine the association of these measurements to findings and symptoms of genitourinary syndrome of menopause METHODS: Healthy volunteers, 80 postmenopausal and 80 premenopausal, were included. Ultrasonographic TVT and TMT measurements, vaginal health index (VHI) scores and pH values were recorded. The daily impact of vaginal aging (DIVA) scale was administered to women in the postmenopausal group.

RESULTS

TVT measurements of the postmenopausal group (6.55 ± 2.00 mm) were lower than the premenopausal group (10.37 ± 2.11 mm) (p: 0.000). TMT measurements of the postmenopausal group (1.46 ± 0.50 mm) were lower than the premenopausal group (2.19 ± 0.60 mm) (p: 0.000). The VHI scores of the postmenopausal group were significantly lower than the premenopausal group, the pH value was higher (p < 0.05). Considering all women TVT and TMT measurements were inversely correlated with pH values and positively correlated with total VHI scores. There was no significant correlation between any component scores of the DIVA scale and TVT, TMT, pH, and VHI total (p > 0.05).

CONCLUSIONS

TVT and TMT measurements in postmenopausal women are significantly lower than premenopausal women. Examination findings and thickness measurements are correlated. Transabdominal ultrasonography is a method that can be used in the evaluation of vaginal thickness which is not painful for the patient, is easy to apply and gives results consistent with the examination findings. However, measurements and examination findings do not correlate with the DIVA scores in postmenopausal women.

The effect of intra-vaginal oxytocin on sexual function in breastfeeding mothers: a randomized triple-blind placebo-controlled trial

BACKGROUND

Considering the importance of sexual function, high prevalence of sexual dysfunction (especially dyspareunia caused by atrophic vaginitis) in breastfeeding women, and lack of effective interventions, the present research aimed to determine the effect of oxytocin (OXT) vaginal gel on sexual function (primary outcome), sexual satisfaction, and depression (secondary outcomes) in the breastfeeding women.

METHODS

This randomized triple-blind controlled trial was conducted on 64 breastfeeding women who referred to health centers in the city of Tabriz, Iran, in 2020-21. Participants were equally assigned to intervention/control groups using block randomization. 200 IU of OXT vaginal gel was given to the participants in the intervention group daily for eight week and the same protocol was carried out for the control group with placebo. Standard questionnaires of Female Sexual Function Index (FSFI), Edinburgh Postpartum Depression Scale (EPDS) and Sexual satisfaction scale for women (SSSW) were completed at baseline and 8 weeks after intervention. ANCOVA test was used to compare post-intervention mean score of the groups, adjusted for the baseline values.

RESULTS

After intervention, there was no statistically significant difference between groups in terms of mean total score of FSFI (Adjusted Mean Difference (AMD): 1.14; 95% Confidence Interval (95% CI): -1.28 to 9.16; P= 0.349) and sexual satisfaction (AMD: 5.01; 95% CI: -0.53 to 10.56; P= 0.075). However, there was statistically significant difference between the groups in terms of mean scores of sexual contentment (AMD: 1.56; 95% CI: 0.29 to 2.83; P = 0.017) and depression (AMD: -1.90; 95% CI: -1.27 to -2.54; P < 0.001). One participant in the OXT group and one participant in the placebo group reported mild uterine contraction and one person in the placebo group reported vaginal burning sensations.

CONCLUSIONS

No evidence was found for the effects of OXT gel in the improvement of FSFI, even though, OXT significantly improved sexual satisfaction in the domain of contentment, and improved the symptoms of depression in comparison to the placebo group. However, a definite conclusion requires more research in this regard.

TRIAL REGISTRATION

the Iranian Registry of Clinical Trials (IRCT), code: IRCT20120718010324N55 , Date of registration: 27/05/2020, URL: https://en.irct.ir/user/trial/44986/view .

Effects of oxytocin versus promestriene on genitourinary syndrome: a pilot, prospective, randomized, double-blind study

OBJECTIVES

In this pilot, prospective, randomized, double-blind study, the authors compared the efficacy of oxytocin with promestriene in improving vaginal atrophy of Genitourinary Syndrome of Menopause (GSM).

METHODS

A total of 51 postmenopausal women with symptoms of GSM were evaluated. They were randomized into two groups: oxytocin (25 patients) and promestriene (26 patients) and were evaluated before and after 90 days of treatment; the evaluation was based on the domains of the Female Sexual Function Index (FSFI) (lubrication, satisfaction, and pain during sexual intercourse), clinical visual examination, and vaginal wall thickness.

RESULTS

After the use of the medications, both groups showed significant improvement in the three evaluated FSFI domains (p < 0.05) and there was no significant difference between the groups (p > 0.05). On clinical examination, the medications improved all the evaluated parameters but without statistical significance (p > 0.05). The evaluation of the thickness of the vaginal epithelium showed that both treatments led to increase in the vaginal epithelium (p < 0.05); however, the efficacy of promestriene was higher than that of oxytocin (p < 0.05).

CONCLUSIONS

Both medications were effective, however, studies with larger samples and longer follow-ups are needed to confirm the clinical applicability.

Non-oestrogenic modalities to reverse urogenital aging

Urogenital aging is a common process affecting all women in the post-menopausal period of their life, and it is substantially due to oestrogen deprivation after ovarian function cessation. These changes can lead to a progressive, chronic, and complex association of symptoms identified as the genitourinary syndrome of menopause, which has a significant impact on quality of life. Genitourinary syndrome and urogenital aging do not resolve spontaneously and usually recur when treatment is stopped. Therefore, appropriate long-term management is of paramount importance, and local oestrogen is the most effective treatment to reverse urogenital aging and to improve symptoms of genitourinary syndrome as replacement therapy. In some women, topical oestrogen may be inconvenient, it may not achieve complete response, or it may be contra-indicated. Several non-hormonal therapies have been investigated, but few treatments have been reported as potentially able to reverse the urogenital aging process similarly to exogenous oestrogens. Laser seems the most promising, although further studies to define its safety and efficacy are mandatory. Vitamin D and E, and phytotherapy have returned conflicting results and require further confirmation. Lifestyle modifications, physiotherapy, and electrical stimulation represent inexpensive and applicable treatments that might slow urogenital aging. Among the hormonal non-oestrogenic therapies, the use of vaginal oxytocin and dehydroepiandrosterone have been found to be effective compared to placebo, as well as the use of oral ospemifene, which partially relieves vulvovaginal atrophy.

Variation in outcome reporting and measurement tools in clinical trials of treatments for genitourinary symptoms in peri- and postmenopausal women: a systematic review

IMPORTANCE

Genitourinary symptoms affect 40% to 60% of postmenopausal women. Evidence-based approaches to diagnosing and managing these symptoms are limited by inconsistencies in outcomes and measures used in clinical trials.

OBJECTIVE

The aim of the study was to systematically review all outcomes and measurement tools reported in randomized clinical trials of interventions for genitourinary symptoms associated with menopause.

EVIDENCE REVIEW

We searched PubMed, Scopus, and the Cochrane Central Register of Controlled Trials (CENTRAL) up to December 2018. Randomized controlled trials with a primary or secondary outcome of genitourinary symptoms associated with menopause, English language, and sample size of 20 or more women per study arm were included. Study characteristics, outcomes, and measurement methods were collected.

FINDINGS

The search yielded 3,478 articles of which 109 met inclusion criteria. Forty-eight different outcomes were reported with "atrophy" as the most common (56/109, 51%) followed by measures of sexual function (19/109, 17%). Almost all (108/109, 99%) trials included patient-reported measures, with 21 different measures and 39 symptom combinations. Clinician-reported scales of vulvovaginal appearance were used in 36 of 109 (33%) trials, with extensive variation in what was measured and reported. Cytological measures from the vaginal epithelium were the most commonly used objective tools (76/109, 70%).

CONCLUSIONS AND RELEVANCE

There is heterogeneity in reported outcomes and measures used in clinical trials of treatments for genitourinary symptoms at menopause and uncertainty as to which outcomes best reflect patient priorities and symptoms. The findings from this systematic review have informed an international survey of stakeholders to determine priorities for outcome selection and reporting. This survey will then inform the development of a Core Outcome Set for use in future clinical trials by the COMMA (Core OutcoMes in MenopAuse) consortium. : Video Summary:http://links.lww.com/MENO/A599.

Safety and Efficacy of an Oxytocin Gel and an Equivalent Gel but Without Hormonal Ingredients (Vagivital® Gel) in Postmenopausal Women with Symptoms of Vulvovaginal Atrophy: A Randomized, Double-Blind Controlled Study

Purpose

The primary objective was to compare the efficacy of 12 weeks of daily treatment with Aqueous Hypromellose-based vaginal (Vagivital^®) gel versus Aqueous Hypromellose-based vaginal gel plus 400 IU oxytocin gel in reducing the severity of the most bothersome vulvovaginal atrophy symptoms (MBS: itching, dysuria, bleeding, and pain/discomfort during vaginal sexual activity) observed at baseline. The secondary objectives were to evaluate the other vulvovaginal atrophy symptoms, vaginal pH, superficial squamous cells, and the safety and tolerability of both gels.

Patients and Methods

This double-blind, randomized study evaluated the safety and efficacy of subjects randomly assigned to 12 weeks of daily intravaginal oxytocin gel (n=79) or Aqueous Hypromellose-based vaginal gel (n=78). The efficacy evaluation was performed using data from all included subjects who fulfilled entry criteria.

Results

Both treatments induced statistically significant reductions in the severity of the MBS from baseline until 4 weeks (Vagivital mean reduction 0.90, p=0.0000; Oxytocin mean reduction 0.82, p=0.0000) and 12 weeks post baseline (Vagivital mean reduction 1.28, p=0.0000; Oxytocin mean reduction 1.16, p=0.0000), but the reduction of MBS severity was not significantly different between the treatment groups at either time point. No serious adverse events were reported in the Aqueous Hypromellose-based vaginal gel group during the treatment period, but one (breast cancer) was reported in the oxytocin gel group (assessed as unlikely related to the study compound).

Conclusion

Significant reductions in the severity of the MBS were seen in both the Aqueous Hypromellose-based vaginal gel and the oxytocin gel groups, but with no significant differences in severity reduction seen between the groups. Both gels were safe and well tolerated. Given the benefits of avoiding the use of hormones, Aqueous Hypromellose-based vaginal gel is an attractive first choice in the treatment of postmenopausal women with vulvovaginal atrophy symptoms.

The efficacy and safety of intravaginal oxytocin on vaginal atrophy: A systematic review

Genitourinary syndrome of menopause is a major issue in menopausal health. Because unlike vasomotor symptoms, it has a progressive trend. In this regard we conducted a systematic review to evaluate the efficacy of intravaginal oxytocin on postmenopausal vaginal atrophy. A search was performed for published studies in Cochrane Library, MEDLINE, Web of Science, Embase, Scopus, ProQuest, Google Scholar and Persian databases without time and language limitations. Only randomized controlled trials that compared intravaginal oxytocin with placebos were included. The outcome measures were objective and subjective assessed symptoms of vaginal atrophy. Statistical heterogeneity was evaluated using the I². The standardized mean differences were pooled the fixed effects model. Of the five included studies, four studies meta-analysed. The meta-analysis in terms of the cytological analysis (standardized mean difference: 35.13, 95% confidence interval: 32.59-37.67, n = 218, I² = 96%) was statistically significant. In terms of histological assessments (standardized mean difference: -0.38, 95% confidence interval: -0.94 to 0.17, n = 38, I² = 0%) and endometrial thickness (standardized mean difference: 0.05, 95% confidence interval: -0.20 to -0.31, n = 95, I² = 0%), there were no statistically significant differences between the groups. Three studies reported a statistically significant improvement in the subjective symptoms; however, we were unable to perform a meta-analysis. Four of the included studies assessed side effects, but only two studies reported them. Oxytocin as a nonestrogenic compound can be a suitable alternative for the treatment of vaginal atrophy, especially in women with contraindications for using estrogenic compounds. Further good quality clinical trials with long-term follow-ups are recommended to demonstrate the effects of intravaginal gel in the treatment of vaginal atrophy.

Chronic oxytocin administration as a tool for investigation and treatment: A cross-disciplinary systematic review

Oxytocin (OT) subserves various physiological, behavioral, and cognitive processes. This paired with the ability to administer OT with minimal and inconsistent side effects has spurred research to explore its therapeutic potential. Findings from single-dose studies indicate that OT administration may be beneficial, at least under certain circumstances. The state of the field, however, is less clear regarding effects from chronic OT administration, which more closely resembles long-term treatment. To address this gap, this review synthesizes existing findings on the use of chronic OT administration in animal and human work. In addition to detailing the effects of chronic OT administration across different functional domains, this review highlights factors that have contributed to mixed findings. Based on this review, a basic framework of interrelated regulatory functions sensitive to chronic OT administration is offered. The paper also identifies future research directions across different contexts, populations, and outcomes, specifically calling for more systematic and standardized research on chronic OT administration in humans to supplement and expand what is currently known from preclinical work.

Role of topical oxytocin in improving vaginal atrophy in postmenopausal women: a randomized, controlled trial

OBJECTIVE AND DESIGN

Prospective randomized controlled trial to test the effectiveness of topical oxytocin gel to improve vaginal atrophy in postmenopausal women.

PATIENTS AND METHODS

A total of 140 postmenopausal women presenting with vaginal atrophy and who satisfied the inclusion and exclusion criteria were randomized into two groups each of 70 patients; they received intravaginal oxytocin gel or placebo gel for 30 days. Serum estrogen level, visual, colposcopic and histological vaginal examination were performed before and after treatment.

RESULTS

Forty-seven out of 70 women in the oxytocin gel group improved after treatment and none in the placebo group (p = 0.001). Forty-five participants in the oxytocin group and seven in the placebo group reported relief of dyspareunia (p = 0.001). Thirty-four participants in the oxytocin group and seven in the placebo group reported relief of soreness (p = 0.001). There was no significant difference between the circulating levels of estradiol in both groups before and after treatment (p = 0.4 and 0.6 for the oxytocin group and the placebo group, respectively).

CONCLUSION

Oxytocin gel is useful in the restoration of the vaginal epithelium in cases of postmenopausal atrophic vaginitis. Further studies with a longer follow-up period are required to test the long-term effects of oxytocin as a treatment for vaginal atrophy.

Oxytocin stimulates cell proliferation in vaginal cell line Vk2E6E7

Objective During and after menopause, the symptoms of vaginal atrophy cause great discomfort and necessitate effective treatment options. Currently, vaginally applied oxytocin is being investigated as a treatment for the symptoms of vaginal atrophy in postmenopausal women. To clarify the mechanisms behind oxytocins effects on vaginal atrophy, the present study investigated the effects of oxytocin on cell proliferation in the cells of the Vk2E6E7 line, a non-tumour vaginal cell line. The study also compared the effects of oxytocin with those of estradiol (E2). Study design The effects of both oxytocin and E2 on the proliferation of Vk2E6E7 cells were investigated using Cell Proliferation ELISA BrdU Colorimetric Assay. The expression of both oxytocin and oxytocin receptor was studied in Vk2E6E7 cells using quantitative real-time polymerase chain reaction and immunofluorescent staining. Main outcome measures Cell proliferation and gene expression. Results Oxytocin increased cell proliferation both time dependently and dose dependently. This differed from the effect pattern observed in cells treated with E2. In addition, in oxytocin-treated cells, the oxytocin receptor was found to be co-localized with caveolin-1, indicating pro-proliferative signalling within the cell. Conclusions Oxytocin stimulates cell proliferation and the co-localization of oxytocin receptor with caveolin-1 in oxytocin-treated cells, supporting the role of oxytocin signalling in cell proliferation. In addition, these findings suggest that increased cell proliferation is one mechanism by which local vaginal oxytocin treatment increases vaginal thickness and relieves vaginal symptoms in postmenopausal women with vaginal atrophy.