Effect of metformin taken in the ‘fresh’in vitrofertilization/intracytoplasmic sperm injection cycle upon subsequent frozen embryo replacement in women with polycystic ovary syndrome

Molecular regulation of polycystic ovary syndrome: altered gene expression levels in mouse models pretreatment and post-treatment

Polycystic ovary syndrome (PCOS) is a complex disorder and genetic factors are believed to play a role. The main aim was to investigate expression levels of genes involved in PI3K/AKT signalling pathway pretreatment and post-treatment. Mouse models of PCOS were generated. Group one included control mice with no polycystic ovaries (n = 4), Group 2 included a PCOS mouse model (n = 8), Group 3 included PCOS mice treated with clomiphene citrate (n = 7) and Group 4 included PCOS mice treated with clomiphene citrate, metformin and pioglitazone (n = 8). Histochemical analyses were performed. Total RNA was extracted and cDNA was synthesized. Irs, Akt1 and Akt2, mTor and Pdpk1 gene expression levels were evaluated by RT-PCR amplification. In Group 1, cortex and medulla were evaluated as normal; in Group 2, ovarian cortex was composed of immature oocytes and cystic follicles with atretic follicles. In Groups 3 and 4, follicles were in the process of normal follicle differentiation. The expression levels of Akt1 and Pi3k were significantly different (P < 0.0001) between Groups 1 and 2. The significant differences in expression levels of Pi3k and Akt1 were also observed between the Group 1 and both Groups 3 and 4 (P < 0.0001). Furthermore, significant variations of the expression levels of mTor between Groups 1 and 4 were observed. The extrapolation of results of this study may imply that follicular development may be regulated by molecular pathways involving Pi3k, Akt1 and mTor expression. Therefore, genes in the PI3K/AKT pathway may have a direct regulatory role in the development of PCOS.

The function of metformin in endometrial receptivity (ER) of patients with polycyclic ovary syndrome (PCOS): a systematic review and meta-analysis

BACKGROUND

This meta-analysis summarizes evidence from studies using metformin (Met) to improve endometrial receptivity (ER) in women with PCOS.

METHODS

Following the PRISMA protocol, we conducted a comprehensive search of academic literature from various databases, including PubMed, EMbase and Cochrane libraries. Studies published in English before Jan 27, 2021, were recruited for primary screening. Data on endometrial thickness (EMT), endometrial artery resistance index (RI), clinical pregnancy rate (CPR) and miscarriage rate (MR) were extracted and analyzed.

RESULTS

Sixty-two eligible studies that included 6571 patients were evaluated in this meta-analysis. Primary indicators are EMT and endometrial aetery RI; secondary indicators include the clinical pregnancy rate and miscarriage rate. Metformin significantly increased EMT (SMD = 2.04, 95% CI (0.96,3.12),P = 0.0002) and reduced endometrial artery RI compared to the non-Met group (SMD = - 2.83, 95% CI: (- 5.06, - 0.59), P = 0.01). As expected, metformin also improved CPR and reduced MR in PCOS patients as a result, clinical pregnancy rate (risk ratio [RR] = 1.26, 95% CI: 1.11-1.43, P = 0.0003), and miscarriage rate (RR = 0.73, 95% CI:0.58-0.91, P = 0.006).

CONCLUSION

Metformin may improve endometrial receptivity (ER) in PCOS patients by increasing EMT and reducing endometrial artery RI. However, the level of most original studies was low, with small sample sizes. More large-scale, long-term RCTs with rigorous methodologies are needed.

The management of anovulatory infertility in women with polycystic ovary syndrome: an analysis of the evidence to support the development of global WHO guidance

BACKGROUND

Here we describe the consensus guideline methodology, summarise the evidence-based recommendations we provided to the World Health Organisation (WHO) for their consideration in the development of global guidance and present a narrative review on the management of anovulatory infertility in women with polycystic ovary syndrome (PCOS).

OBJECTIVE AND RATIONALE

The aim of this paper was to present an evidence base for the management of anovulatory PCOS.

SEARCH METHODS

The evidence to support providing recommendations involved a collaborative process for: (i) identification of priority questions and critical outcomes, (ii) retrieval of up-to-date evidence and exiting guidelines, (iii) assessment and synthesis of the evidence and (iv) the formulation of draft recommendations to be used for reaching consensus with a wide range of global stakeholders. For each draft recommendation, the methodologist evaluated the quality of the supporting evidence that was then graded as very low, low, moderate or high for consideration during consensus.

OUTCOMES

Evidence was synthesized and we made recommendations across the definition of PCOS including hyperandrogenism, menstrual cycle regulation and ovarian assessment. Metabolic features and the impact of ethnicity were covered. Management includes lifestyle changes, bariatric surgery, pharmacotherapy (including clomiphene citrate (CC), aromatase inhibitors, metformin and gonadotropins), as well as laparoscopic surgery. In-vitro fertilization (IVF) was considered as were the risks of ovulation induction and of pregnancy in PCOS. Approximately 80% of women who suffer from anovulatory infertility have PCOS. Lifestyle intervention is recommended first in women who are obese largely on the basis of general health benefits. Bariatric surgery can be considered where the body mass index (BMI) is ≥35 kg/m2 and lifestyle therapy has failed. Carefully conducted and monitored pharmacological ovulation induction can achieve good cumulative pregnancy rates and multiple pregnancy rates can be minimized with adherence to recommended protocols. CC should be first-line pharmacotherapy for ovulation induction and letrozole can also be used as first-line therapy. Metformin alone has limited benefits in improving live birth rates. Gonadotropins and laparoscopic surgery can be used as second-line treatment. There is no clear evidence for efficacy of acupuncture or herbal mixtures in women with PCOS. For women with PCOS who fail lifestyle and ovulation induction therapy or have additional infertility factors, IVF can be used with the safer gonadotropin releasing hormone (GnRH) antagonist protocol. If a GnRH-agonist protocol is used, metformin as an adjunct may reduce the risk of ovarian hyperstimulation syndrome. Patients should be informed of the potential side effects of ovulation induction agents and of IVF on the foetus, and of the risks of multiple pregnancy. Increased risks for the mother during pregnancy and for the child, including the exacerbating impact of obesity on adverse outcomes, should also be discussed.

WIDER IMPLICATIONS

This guidance generation and evidence-synthesis analysis has been conducted in a manner to be considered for global applicability for the safe administration of ovulation induction for anovulatory women with PCOS.

Metformin therapy in a hyperandrogenic anovulatory mutant murine model with polycystic ovarian syndrome characteristics improves oocyte maturity during superovulation

Background

Metformin, an oral biguanide traditionally used for the treatment of type 2 diabetes, is widely used for the management of polycystic ovary syndrome (PCOS)-related anovulation. Because of the significant prevalence of insulin resistance and glucose intolerance in PCOS patients, and their putative role in ovulatory dysfunction, the use of metformin was touted as a means to improve ovulatory function and reproductive outcomes in PCOS patients. To date, there has been inconsistent evidence to demonstrate a favorable effect of metformin on oocyte quality and competence in women with PCOS. Given the heterogeneous nature of this disorder, we hypothesized that metformin may be beneficial in mice with aberrant metabolic characteristics similar to a significant number of PCOS patients. The aim of this study was to gain insight into the in vitro and in vivo effects of metformin on oocyte development and ovulatory function.

Methods

We utilized metformin treatment in the transgenic ob/ob and db/db mutant murine models which demonstrate metabolic and reproductive characteristics similar to women with PCOS. Results: Metformin did not improve in vitro oocyte maturation nor did it have an appreciable effect on in vitro granulosa cell luteinization (progesterone production) in any genotype studied. Although both mutant strains have evidence of hyperandrogenemia, anovulation, and hyperinsulinemia, only db/db mice treated with metformin had a greater number of mature oocytes and total overall oocytes compared to control. There was no observed impact on body mass, or serum glucose and androgens in any genotype.

Conclusions

Our data provide evidence to suggest that metformin may optimize ovulatory performance in mice with a specific reproductive and metabolic phenotype shared by women with PCOS. The only obvious difference between the mutant murine models is that the db/db mice have elevated leptin levels raising the questions of whether their response to metformin is related to elevated leptin levels and/or if a subset of PCOS women with hyperleptinemia may be responsive to metformin therapy. Further study is needed to better define a subset of women with PCOS that may be responsive to metformin.