Assessment of ovarian stromal blood flow after metformin treatment in women with polycystic ovary syndrome

Biomechanical forces and signals operating in the ovary during folliculogenesis and their dysregulation: implications for fertility

BACKGROUND

Folliculogenesis occurs in the highly dynamic environment of the ovary. Follicle cyclic recruitment, neo-angiogenesis, spatial displacement, follicle atresia and ovulation stand out as major events resulting from the interplay between mechanical forces and molecular signals. Morphological and functional changes to the growing follicle and to the surrounding tissue are required to produce oocytes capable of supporting preimplantation development to the blastocyst stage.

OBJECTIVE AND RATIONALE

This review will summarize the ovarian morphological and functional context that contributes to follicle recruitment, growth and ovulation, as well as to the acquisition of oocyte developmental competence. We will describe the changes occurring during folliculogenesis to the ovarian extracellular matrix (ECM) and to the vasculature, their influence on the mechanical properties of the ovarian tissue, and, in turn, their influence on the regulation of signal transduction. Also, we will outline how their dysregulation might be associated with pathologies such as polycystic ovary syndrome (PCOS), endometriosis or premature ovarian insufficiency (POI). Finally, for each of these three pathologies, we will highlight therapeutic strategies attempting to correct the altered biomechanical context in order to restore fertility.

SEARCH METHODS

For each area discussed, a systematic bibliographical search was performed, without temporal limits, using PubMed Central, Web of Science and Scopus search engines employing the keywords extracellular matrix, mechanobiology, biomechanics, vasculature, angiogenesis or signalling pathway in combination with: ovary, oogenesis, oocyte, folliculogenesis, ovarian follicle, theca, granulosa, cumulus, follicular fluid, corpus luteum, meiosis, oocyte developmental competence, preimplantation, polycystic ovary syndrome, premature ovarian insufficiency or endometriosis.

OUTCOMES

Through search engines queries, we yielded a total of 37 368 papers that were further selected based on our focus on mammals and, specifically, on rodents, bovine, equine, ovine, primates and human, and also were trimmed around each specific topic of the review. After the elimination of duplicates, this selection process resulted in 628 papers, of which 287 were cited in the manuscript. Among these, 89.2% were published in the past 22 years, while the remaining 8.0%, 2.4% or 0.3% were published during the 1990s, 1980s or before, respectively. During folliculogenesis, changes occur to the ovarian ECM composition and organization that, together with vasculature modelling around the growing follicle, are aimed to sustain its recruitment and growth, and the maturation of the enclosed oocyte. These events define the scenario in which mechanical forces are key to the regulation of cascades of molecular signals. Alterations to this context determine impaired folliculogenesis and decreased oocyte developmental potential, as observed in pathological conditions which are causes of infertility, such as PCOS, endometriosis or POI.

WIDER IMPLICATIONS

The knowledge of these mechanisms and the rules that govern them lay a sound basis to explain how follicles recruitment and growth are modulated, and stimulate insights to develop, in clinical practice, strategies to improve follicular recruitment and oocyte competence, particularly for pathologies like PCOS, endometriosis and POI.

The effect of melatonin on ultrasound markers of follicular development: A double-blind placebo-controlled randomised trial

BACKGROUND

Melatonin is a potent oxygen scavenger and is capable of altering blood flow in various vascular beds.

AIMS

We aimed to determine the effect of melatonin on ovarian vascular indices during ovarian stimulation for in vitro fertilisation (IVF).

MATERIALS AND METHODS

This is a pilot double-blind placebo-controlled randomised trial. Sixty-nine women (mean age 35.8 ± 4.3 years) undergoing their first cycle of IVF were randomised to receive either placebo, 2, 4 or 8 mg of melatonin, twice a day. Each participant underwent a transvaginal ultrasound at days 6-10 assessing follicular number and size. The vascularisation index (VI), flow index (FI) and vascularisation-flow index (VFI) were measured. These indices were then correlated with embryological outcomes. Informed consent was obtained from participants. This trial was registered with the Australia New Zealand Clinical Trials Registry (ACTRN12613001317785).

RESULTS

The number of follicles did not differ between groups (P = 0.4). There were no differences in the VI (P = 0.4), FI (P = 0.1) or VFI (P = 0.3) in the right ovary or the FI (P = 0.3) or VFI (P = 0.3) in the left ovary between groups. When comparing placebo to any dose of melatonin, there were no differences in any measured parameter. While there was correlation between the number of follicles on ultrasound and all measured embryological outcomes, there was no correlation between ovarian vascular indices and these important clinical outcomes.

CONCLUSIONS

Melatonin does not appear to change ovarian vascular indices during ovarian stimulation. In addition, such vascular indices cannot predict the number or quality of oocytes or embryos obtained in an IVF cycle. These findings require confirmation in future larger studies.

Metformin metabolic and vascular effects in overweight/moderately obese hyperinsulinemic PCOS patients treated with contraceptive vaginal ring: a pilot study

The aim of this pilot study was to assess how metformin, associated with a contraceptive vaginal ring, may influence lipid and carbohydrate metabolism, fat distribution, and surrogate markers of arterial function. Among 62 patients, 25 were treated with vaginal ring plus metformin and 37 women with only vaginal ring. The effects were assessed after 6 months. The patients were submitted to evaluation of lipid and carbohydrate metabolism; extended view ultrasonographic evaluation of fat distribution; Doppler analysis of ophthalmic artery; brachial artery flow-mediated vasodilatation; oral glucose tolerance test. After 6 months, the body mass index and waist/hip ratio resulted significantly better in patients who associated metformin to vaginal ring. The fasting glucose, insulin, and glucose/insulin ratio, HOMA-IR, glucose, and insulin AUC 120 were significantly improved in metformin group. The ultrasonographic fat analysis resulted significantly better after metformin. The ophthalmic artery PI significantly improved in metformin group. The brachial artery vasodilation was better in metformin treated patients. In conclusion, metformin, associated with vaginal ring, improves the insulin and carbohydrate metabolism, reduces the body weight and android fat distribution. This, associated with the significant improvements of surrogate markers of arterial function, may be responsible of possible cardiovascular and cerebrovascular protective effects.

The effect of myoinositol on ovarian blood flows in women with polycystic ovary syndrome

To evaluate whether 4 gram myoinositol and 400 mcg folic acid(MYO) therapy has any effects on ovarian stromal blood flow by using pulsed and color Doppler at 3 months follow-up period in polycystic ovary syndrome (PCOS). One-hundred eighty patients were designed into six groups; Group 1: PCOS patients that received OCP containing 30 mcg ethinyl estradiol (EE) plus 3 mg drospirenone (DRP); Group 2: PCOS patients that received MYO; Group 3: PCOS patients that received no medication. Group 4: Healthy patients that received OCP; Group 5: Healthy patients that received MYO; Group 6: Healthy patients that received no medication. Resistance index (RI) and pulsatility index (PI) of both ovaries were assessed. There was a significant increase in RI and PI of both ovarian stromal blood flow women with PCOS who received OCP (Group 1, p < .001) and MYO (Group 2, p < .001). The rate of increment in both RI and PI values were similar for OCP users (Group 1) and MYO users(Group2) in PCOS patients. MYO therapy reduced ovarian vascularization in both PCOS and healthy users after 3 months and this decrease is especially noticeable in women with PCOS compared to healthy women. OCP therapy also reduced ovarian vascularization just like MYO therapy.

Doppler analysis of ovarian stromal blood flow changes after treatment with metformin versus ethinyl estradiol-cyproterone acetate in women with polycystic ovarian syndrome: A randomized controlled trial

OBJECTIVES

To evaluate the effects of oral contraceptive pill (OCP) and metformin at the end of 6 months of treatment on ovarian stromal blood flow by using pulsed and color Doppler in women with PCOS.

METHODS

Women with PCOS (n=101) fulfilling the Rotterdam criteria were enrolled and randomized to receive either OCP or metformin. OCP was administered in cycles of 28 days (21 pills containing 35μg of ethinylestradiol plus 2mg of cyproterone acetate followed by 7 placebo pills) for six cycles and metformin 500mg was administered twice daily for 6 months. Clinical, anthropometric, hormonal and metabolic parameters and resistance index (RI) and pulsatility index (PI) of both ovarian stromal vessels were assessed before and after treatment.

RESULTS

OCP resulted in a higher reduction in serum luteinizing hormone (LH) and androgens whereas metformin resulted in significant reduction in BMI, waist circumference, and insulin resistance. There was a significant increase in RI and PI of both ovarian stromal vessels with both drugs post-treatment, however, the increase was more prominent in the OCP group. There was a significant negative correlation between changes in LH and testosterone levels with changes in PI and RI in OCP group whereas changes in serum fasting insulin levels negatively correlated with changes in PI and RI values in the Metformin group.

CONCLUSIONS

Treatment with both OCP and metformin leads to a reduction in ovarian stromal vascularization in PCOS women perhaps through different mechanisms and this reduction is more prominent with OCP.

Ovarian angiogenesis in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most prevalent endocrine pathology among women in reproductive age. Its main symptoms are oligo or amenorrhea, hyperandrogenism and the presence of ovarian cysts. It is also associated with infertility, obesity and insulin resistance. Mainly due to its heterogeneity, PCOS treatments are directed to manage its symptoms and to prevent associated diseases. The correct formation and regression of blood vessels during each ovarian cycle is indispensable for proper follicular development, ovulation and corpus luteum formation. The importance of these processes opened a new and promising field: ovarian angiogenesis. Vascular alterations characterize numerous pathologies, either with increased, decreased or abnormal angiogenesis. In the last years, several anomalies of ovarian angiogenesis have been described in women with PCOS. Therefore, it has been suggested that these alterations may be associated with the decreased - or lack of - ovulation rates and for the formation of cysts in the PCOS ovaries. Restoration of a proper vessel formation in the ovaries may lead to improved follicular development and ovulation in these patients. In the present review, we attempt to summarize the alterations in ovarian angiogenesis that have been described in women with PCOS. We also discuss the therapeutic approaches aimed to correct these alterations and their beneficial effects on the treatment of infertility in PCOS.

Impact of transvaginal hydrolaparoscopy ovarian drilling on ovarian stromal blood flow and ovarian volume in clomiphene citrate-resistant PCOS patients: a case-control study

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in gynecology. In PCOS patients vascularization parameters are altered. Transvaginal hydrolaparoscopy (THL) is a mini-invasive approach for ovarian drilling in PCOS patients. In this study, we assessed the effect of ovarian drilling using THL on ovarian volume (OV) and vascularization index (VI) using 3D power Doppler ultrasonography in CC-resistant PCOS patients. A case-control study on 123 CC-resistant PCOS women who underwent THL ovarian drilling was performed. Patients underwent 3D ultrasound and power Doppler to measure VI, flow index (FI), vascularization flow index (VFI) and to evaluate OV before and after the procedure, at six months, and on the early follicular phase of the menstrual cycle. After THL ovarian drilling, OV and power Doppler flow indices were significantly reduced compared to pre-operative values (OV: 7.85 versus 11.72 cm³, p < 0.01; VI: 2.50 versus 4.81, p < 0.01; VFI: 1.10 versus 2.16, p < 0.01; FI: 32.05 versus 35.37, p < 0.01). In conclusion, THL ovarian drilling seems to reduce OV and 3D power Doppler indices, and could therefore be a viable alternative to LOD in PCOS patients resistant to medical therapy.

Value of in situ ovarian volume measured during cesarean delivery to assess the potential of diminished ovarian reserve

OBJECTIVE

We aimed to determine the value of mean ovarian volume (OV) determined by three-dimensional in situ measurement of ovaries during cesarean delivery (CD) to assess the potential of diminished ovarian reserve (DOR) evaluated by hormonal and ultrasonographic parameters 3 months after the cesarean delivery.

METHODS

Each ovary was measured underwent CD in three dimensions, and three months after CD, the mean OV, serum AMH, FSH, LH, and estradiol levels, and antral follicle count (AFC) values were recorded as well as other demographic and obstetric parameters.

RESULTS

After categorizing the study subjects as having a potential of DOR by the criteria of serum AMH <1 pg/mL and AFC value ≤6, in patients with a potential of DOR, the mean intra-operative and post-operative OVs were significantly decreased (p < 0.05). Considering the correlation coefficients obtained by the correlations of post-operative AMH level and AFC value with the mean intra-operative and post-operative OV values, the mean intra-operative OV provided significantly higher correlation coefficients (p < 0.05).

CONCLUSIONS

These findings, overall, support the diagnostic value of mean OV determined by the in situ measurement of three dimensions of left and right ovaries during cesarean delivery for the screening of potential for the DOR.