Uterine effects of metformin administration in anovulatory women with polycystic ovary syndrome

Metformin ameliorates endometrial thickness in a rat model of thin endometrium

Metformin, a well-established anti-diabetic drug, is also used in managing various other metabolic disorders including polycystic ovarian syndrome (PCOS). There are evidences to show that metformin improves endometrial functions in PCOS women. However, fewer studies have explored the direct effects of metformin on endometrium. Previous in vitro studies have shown that therapeutic serum concentrations of metformin enhance endometrial epithelial cell proliferation. The present study was undertaken to investigate in vivo effects of metformin on endometrial proliferation in a rat model of thin endometrium. Toward this, a rat model of thin endometrium was developed. Metformin (0.1% or 1% w/v) was administrated orally for 15 days in rats with thin endometrium. Oral metformin administration for three consecutive estrous cycles (15 days) in the thin endometrium rat model led to an increase in endometrial thickness compared to sham endometrium. Histological analysis showed a significant increase in the number of endometrial glands (P < 0.05), stromal cells (P < 0.01) and blood vessels (P < 0.01) in metformin-treated (n = 10 in each group) uterine horns compared to sham (saline-treated) uterine horns in rats. The expression of proliferating cell nuclear antigen and vascular epithelial growth factor was found to be upregulated on treatment with 1% metformin-treated group (n = 7). However, pregnancy outcomes in the rats treated with metformin remained unaltered despite the restoration of endometrial thickness. In conclusion, the study demonstrated that metformin ameliorates endometrial thickness in a rat model of thin endometrium by increasing endometrial proliferation and angiogenesis, without restoration of embryo implantation.

Effects of N-acetylcysteine and metformin treatment on the stereopathological characteristics of uterus and ovary

In this study, the stereo-pathological effect of metformin and N-acetyl cysteine is evaluated on the uterus and ovary of polycystic ovary syndrome (PCOS) mice. 96 mature females (8-weekold, weight of 20–30 gr) BALB/c mice were classified into 6 groups including the control group (n= 16), letrozole-induced PCOS group (n=16), PCOS + metformin (n=16), PCOS+NAC (n=16) and a separate control group for NAC (n=16). Another PCOS group was maintained for a month to make sure that features remain till the end of the study. Testosterone level, vaginal cytology and stereological evaluations were assessed. Vaginal cytology in letrozole-receiving mice showed a diestrus phase continuity. Testosterone level, body weight, uterine weight, endometrial volume, myometrial volume, gland volume, stromal volume, epithelial volume, vessel volume, daughter and conglomerate glands, endometrial thickness, and myometrial thickness exhibited an increasing trend in the uterus of PCOS mice. While normal gland and vessel length decreased in the PCOS group. Ovarian volume, corticomedullary volume, primary follicles, secondary follicles, and ovarian cysts were increased in PCOS ovaries. While corpus luteum, primordial, graafian, and atretic follicles showed a decline in the PCOS group. NAC and metformin, however, managed to restore the condition to normal. Given the prevalence of PCOS and its impact on fertility, the use of noninvasive methods is of crucial significance. NAC can control and treat pathological parameters and help as a harmless drug in the treatment of women with PCOS.

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.

Endometrial Glucose Transporters in Health and Disease

Pregnancy loss is a frequent occurrence during the peri-implantation period, when there is high glucose demand for embryonic development and endometrial decidualization. Glucose is among the most essential uterine fluid components required for those processes. Numerous studies associate abnormal glucose metabolism in the endometrium with a higher risk of adverse pregnancy outcomes. The endometrium is incapable of synthesizing glucose, which thus must be delivered into the uterine lumen by glucose transporters (GLUTs) and/or the sodium-dependent glucose transporter 1 (SGLT1). Among the 26 glucose transporters (14 GLUTs and 12 SGLTs) described, 10 (9 GLUTs and SGLT1) are expressed in rodents and 8 (7 GLUTs and SGLT1) in the human uterus. This review summarizes present knowledge on the most studied glucose transporters in the uterine endometrium (GLUT1, GLUT3, GLUT4, and GLUT8), whose data regarding function and regulation are still lacking. We present the recently discovered SGLT1 in the mouse and human endometrium, responsible for controlling glycogen accumulation essential for embryo implantation. Moreover, we describe the epigenetic regulation of endometrial GLUTs, as well as signaling pathways included in uterine GLUT’s expression. Further investigation of the GLUTs function in different endometrial cells is of high importance, as numerous glucose transporters are associated with infertility, polycystic ovary syndrome, and gestational diabetes.

The effects of metformin treatment on the ovaries and uterus of offspring

OBJECTIVE

The aim of this study is to investigate the effects of metformin treatment at different dosage levels on the ovaries and uteruses of rat offspring in the course of the intrauterine period.

METHODS

 Saline, metformin (100 mg/kg/day), and metformin (200 mg/kg/day) were administered via oral gavage between the 6th and 15th days of gestation to the 9 pregnant rats (n = 3/group). After birth, 5 female offspring were separated from each group and perfused on the 60th day of postnatal development. The cortex and medulla volumes of the ovaries, the thicknesses of epithelium and endometrium of the uteruses and the total oocyte number density were estimated. In addition, the estradiol levels in blood samples were measured by the ELISA method.

RESULTS

There were no statistically significant differences among the groups regarding the number of oocytes, the volumes of ovarian cortex, medulla, primary and secondary follicles (p > .05). In comparison with the control group, the volume of the tertiary follicle, the thickness of the uterus epithelium, and the estradiol level were significantly decreased in Metformin 200 group (p < .05).

CONCLUSIONS

The gestational exposure to high dose metformin may result in decreased estradiol production and subsequently decreased endometrial thickness of offspring rats.

Endometriosis and polycystic ovary syndrome are diametric disorders

Evolutionary and comparative approaches can yield novel insights into human adaptation and disease. Endometriosis and polycystic ovary syndrome (PCOS) each affect up to 10% of women and significantly reduce the health, fertility, and quality of life of those affected. PCOS and endometriosis have yet to be considered as related to one another, although both conditions involve alterations to prenatal testosterone levels and atypical functioning of the hypothalamic-pituitary-gonadal (HPG) axis. Here, we propose and evaluate the novel hypothesis that endometriosis and PCOS represent extreme and diametric (opposite) outcomes of variation in HPG axis development and activity, with endometriosis mediated in notable part by low prenatal and postnatal testosterone, while PCOS is mediated by high prenatal testosterone. This diametric disorder hypothesis predicts that, for characteristics shaped by the HPG axis, including hormonal profiles, reproductive physiology, life-history traits, and body morphology, women with PCOS and women with endometriosis will manifest opposite phenotypes. To evaluate these predictions, we review and synthesize existing evidence from developmental biology, endocrinology, physiology, life history, and epidemiology. The hypothesis of diametric phenotypes between endometriosis and PCOS is strongly supported across these diverse fields of research. Furthermore, the contrasts between endometriosis and PCOS in humans parallel differences among nonhuman animals in effects of low versus high prenatal testosterone on female reproductive traits. These findings suggest that PCOS and endometriosis represent maladaptive extremes of both female life-history variation and expression of sexually dimorphic female reproductive traits. The diametric disorder hypothesis for endometriosis and PCOS provides novel, unifying, proximate, and evolutionary explanations for endometriosis risk, synthesizes diverse lines of research concerning the two most common female reproductive disorders, and generates future avenues of research for improving the quality of life and health of women.

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.

An Update on the Progress of Endometrial Receptivity in Women with Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a significant public health issue with diverse presentations, including reproductive, metabolic, and psychological disorders. Although problems with ovulation, metabolism, and hormonal imbalance can be pharmacologically improved, even the excellent quality of transferred embryos does not necessarily increase the pregnancy rate. Poor endometrial receptivity in women with PCOS perturbs endometrial decidualization and blastocyst implantation, increasing adverse pregnancy outcomes, such as miscarriage and poor embryonic development. The etiological and pathophysiological mechanisms involved in defective endometrial receptivity in women with PCOS have not been fully elucidated to date. Various contributing factors have been reported as primary causes of defective endometrial receptivity in women with PCOS, including metabolic alterations, inflammatory events, and some abnormally expressed endometrial molecular markers. However, few studies to date have investigated in depth the complex mechanisms underlying the compromised endometrial receptivity in women with PCOS. This article reviews recent reports mainly on metabolic alterations and some new endometrial molecular markers in order to collate the existing data and improve our understanding in this field. The aim was to discuss current novel insights on defective endometrial receptivity in women with PCOS in order to provide a theoretical basis for reducing adverse pregnancy outcomes and improving the live birth rate in PCOS.

Endometrial function in women with polycystic ovary syndrome: a comprehensive review

BACKGROUND

Polycystic ovary syndrome (PCOS) is the most common cause of anovulatory infertility. An endometrial component has been suggested to contribute to subfertility and poor reproductive outcomes in affected women.

OBJECTIVE AND RATIONALE

The aim of this review was to determine whether there is sufficient evidence to support that endometrial function is altered in women with PCOS, whether clinical features of PCOS affect the endometrium, and whether there are evidence-based interventions to improve endometrial dysfunction in PCOS women.

SEARCH METHODS

An extensive literature search was performed from 1970 up to July 2020 using PubMed and Web of Science without language restriction. The search included all titles and abstracts assessing a relationship between PCOS and endometrial function, the role played by clinical and biochemical/hormonal factors related to PCOS and endometrial function, and the potential interventions aimed to improve endometrial function in women with PCOS. All published papers were included if considered relevant. Studies having a specific topic/hypothesis regarding endometrial cancer/hyperplasia in women with PCOS were excluded from the analysis.

OUTCOMES

Experimental and clinical data suggest that the endometrium differs in women with PCOS when compared to healthy controls. Clinical characteristics related to the syndrome, alone and/or in combination, may contribute to dysregulation of endometrial expression of sex hormone receptors and co-receptors, increase endometrial insulin-resistance with impaired glucose transport and utilization, and result in chronic low-grade inflammation, immune dysfunction, altered uterine vascularity, abnormal endometrial gene expression and cellular abnormalities in women with PCOS. Among several interventions to improve endometrial function in women with PCOS, to date, only lifestyle modification, metformin and bariatric surgery have the highest scientific evidence for clinical benefit.

WIDER IMPLICATIONS

Endometrial dysfunction and abnormal trophoblast invasion and placentation in PCOS women can predispose to miscarriage and pregnancy complications. Thus, patients and their health care providers should advise about these risks. Although currently no intervention can be universally recommended to reverse endometrial dysfunction in PCOS women, lifestyle modifications and metformin may improve underlying endometrial dysfunction and pregnancy outcomes in obese and/or insulin resistant patients. Bariatric surgery has shown its efficacy in severely obese PCOS patients, but a careful evaluation of the benefit/risk ratio is warranted. Large scale randomized controlled clinical trials should address these possibilities.

Differential Expression Patterns of Glycolytic Enzymes and Mitochondria-Dependent Apoptosis in PCOS Patients with Endometrial Hyperplasia, an Early Hallmark of Endometrial Cancer, In Vivo and the Impact of Metformin In Vitro

The underlying mechanisms of polycystic ovarian syndrome (PCOS)-induced endometrial dysfunction are not fully understood, and although accumulating evidence shows that the use of metformin has beneficial effects in PCOS patients, the precise regulatory mechanisms of metformin on endometrial function under PCOS conditions have only been partially explored. To address these clinical challenges, this study aimed to assess the protein expression patterns of glycolytic enzymes, estrogen receptor (ER), and androgen receptor (AR) along with differences in mitochondria-dependent apoptosis in PCOS patients with and without endometrial hyperplasia in vivo and to investigate the effects of metformin in PCOS patients with endometrial hyperplasia in vitro. Here, we showed that compared to non-PCOS patients and PCOS patients without hyperplasia, the endometria from PCOS patients with hyperplasia had a distinct protein expression pattern of glycolytic enzymes, including pyruvate kinase isozyme M2 isoform (PKM2) and pyruvate dehydrogenase (PDH), and mitochondrial transcription factor A (TFAM). In PCOS patients with endometrial hyperplasia, increased glandular epithelial cell secretion and infiltrated stromal cells in the glands were associated with decreased PDH immunoreactivity in the epithelial cells. Using endometrial tissues from PCOS patients with hyperplasia, we found that in response to metformin treatment in vitro, hexokinase 2 (HK2) expression was decreased, whereas phosphofructokinase (PFK), PKM2, and lactate dehydrogenase A (LDHA) expression was increased compared to controls. Although there was no change in PDH expression, metformin treatment increased the expression of TFAM and cleaved caspase-3. Moreover, our in vivo study showed that while endometrial ERβ expression was no different between non-PCOS and PCOS patients regardless of whether or not hyperplasia was present, ERα and AR protein expression was gradually increased in women with PCOS following the onset of endometrial hyperplasia. Our in vitro study showed that treatment with metformin inhibited ERα expression without affecting ERβ expression. Our findings suggest that decreased glycolysis and increased mitochondrial activity might contribute to the onset of ERα-dependent endometrial hyperplasia and that metformin might directly reverse impaired glycolysis and normalize mitochondrial function in PCOS patients with endometrial hyperplasia.

Metformin inhibits estradiol and progesterone-induced decidualization of endometrial stromal cells by regulating expression of progesterone receptor, cytokines and matrix metalloproteinases

BACKGROUND

Polycystic ovary syndrome (PCOS) is a serious threat for reproductive-aged women. Metformin has been used for the treatment of PCOS. However, its molecular mechanism in decidualization process of PCOS has not been well featured.

METHODS

RT-qPCR analysis was used to detect expression patterns of progesterone receptor (PGR), estradiol receptor alpha (ERα), Cytokeratin 8 and Vimentin in endometrial tissues of PCOS and non-PCOS patients. RT-qPCR assay was also employed to determine mRNA expression of prolactin, Insulin-like growth factor-binding protein 1 (IGFBP-1), matrix metalloproteinase-2 (MMP-2) and matrix metalloproteinase-9 (MMP9). Cytokine secretion were measured by matching ELISA kits. Protein expression of p-ERK1/2, ERK1/2, p-p38 MAPK, p38 MAPK, and PGR (PGRA and PGRB) was tested by western blot assay.

RESULTS

PGR expression was upregulated in PCOS patients. Metformin alleviated estradiol (E2) and progesterone (P4) (EP)-induced decidualization of endometrial stromal cells. Abnormal cytokine secretion was observed in EP-stimulated endometrial stromal cells in the absence or presence of metfromin. Metformin suppressed EP-induced MMP-2 and MMP-9 upregulation. Metformin alleviated EP-triggered p38 MAPK inactivation and PGR (PGRA and PGRB) expression. Metfromin had no effect on ERK1/2 signaling in EP-stimulated endometrial stromal cells.

CONCLUSION

Metformin alleviated EP-induced decidualization of endometrial stromal cells by modulating secretion of multiple cytokines, inhibiting expression of MMP-2 and MMP-9, activating p38-MAPK signaling and reducing PGR expression, providing a deep insight into the molecular basis of metfromin therapy for PCOS patients.

Uterine progesterone signaling is a target for metformin therapy in PCOS-like rats

Impaired progesterone (P4) signaling is linked to endometrial dysfunction and infertility in women with polycystic ovary syndrome (PCOS). Here, we report for the first time that elevated expression of progesterone receptor (PGR) isoforms A and B parallels increased estrogen receptor (ER) expression in PCOS-like rat uteri. The aberrant PGR-targeted gene expression in PCOS-like rats before and after implantation overlaps with dysregulated expression of Fkbp52 and Ncoa2, two genes that contribute to the development of uterine P4 resistance. In vivo and in vitro studies of the effects of metformin on the regulation of the uterine P4 signaling pathway under PCOS conditions showed that metformin directly inhibits the expression of PGR and ER along with the regulation of several genes that are targeted dependently or independently of PGR-mediated uterine implantation. Functionally, metformin treatment corrected the abnormal expression of cell-specific PGR and ER and some PGR-target genes in PCOS-like rats with implantation. Additionally, we documented how metformin contributes to the regulation of the PGR-associated MAPK/ERK/p38 signaling pathway in the PCOS-like rat uterus. Our data provide novel insights into how metformin therapy regulates uterine P4 signaling molecules under PCOS conditions.

Metformin Ameliorates Uterine Defects in a Rat Model of Polycystic Ovary Syndrome

Adult rats treated concomitantly with insulin and human chorionic gonadotropin exhibit endocrine, metabolic, and reproductive abnormalities that are very similar to those observed in polycystic ovary syndrome (PCOS) patients. In this study, we used this rat model to assess the effects of metformin on PCOS-related uterine dysfunction. In addition to reducing androgen levels, improving insulin sensitivity, and correcting the reproductive cycle, metformin treatment induced morphological changes in the PCOS-like uterus. At the molecular and cellular levels, metformin normalized the androgen receptor-mediated transcriptional program and restored epithelial–stromal interactions. In contrast to glucose transport, uterine inflammatory gene expression was suppressed through the PI3K–Akt–NFκB network, but without affecting apoptosis. These effects appeared to be independent of AMPK subunit and autophagy-related protein regulation. We found that when metformin treatment partially restored implantation, several implantation-related genes were normalized in the PCOS-like rat uterus. These results improve our understanding of how metformin rescues the disruption of the implantation process due to the uterine defects that result from hyperandrogenism and insulin resistance. Our data provide insights into the molecular and functional clues that might help explain, at least in part, the potential therapeutic options of metformin in PCOS patients with uterine dysfunction.

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The therapeutic dose of metformin sufficiently suppresses hyperandrogenism and insulin resistance.

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Metformin inhibits uterine androgen receptor (AR)-dependent gene expression to restore epithelial–stromal interactions.

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Metformin reduces uterine inflammation through the PI3K–Akt–NFκB pathway.

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Metformin partially restores implantation in PCOS-like rats.

The systemic benefits of metformin therapy for women with polycystic ovary syndrome (PCOS) are widely appreciated, but knowledge of the molecular mechanisms of its action and to what extent it beneficially affects uterine function is limited. Using a PCOS-like rat model, we show that treatment with metformin can reverse the negative effects of androgenic and inflammatory conditions in the rat uterus. Importantly, we find that the sustained benefit of metformin is to rescue implantation failure in some PCOS-like rats. Thus, our data will be of translational value in the clinical management of metformin treatment in PCOS patients with uterine dysfunction.

Effect of maternal PCOS and PCOS-like phenotype on the offspring's health

Polycystic ovary syndrome (PCOS) is a heterogeneous endocrine disorder with both reproductive and metabolic abnormalities affecting women of reproductive age. While the exact origin of PCOS is unknown, observations from clinical and animal studies suggest that maternal hyperandrogenism may be a contributing factor. Because women with PCOS manifest hyperandrogenism during pregnancy, changes in the gestational endocrine milieu may play a role in the vertical transmission of this syndrome. This review discusses the potential developmental origins of PCOS, the impact of maternal PCOS on the offspring's health and contributions of the postnatal environment, capitalizing on findings from animal models that exhibit a PCOS-like phenotype. In addition, this review highlights the scarcity of data at early gestational stages in humans and the importance of animal experimentation to better understand the cellular and molecular mechanisms involved in the programming of adult diseases, therefore, helping identify therapeutic targets for preventive and treatment strategies.

Fertile ground: human endometrial programming and lessons in health and disease

The human endometrium is a highly dynamic tissue that is cyclically shed, repaired, regenerated and remodelled, primarily under the orchestration of oestrogen and progesterone, in preparation for embryo implantation. Humans are among the very few species that menstruate and that, consequently, are equipped with unique cellular and molecular mechanisms controlling these cyclic processes. Many reproductive pathologies are specific to menstruating species, and studies in animal models rarely translate to humans. Abnormal remodelling and regeneration of the human endometrium leads to a range of reproductive complications. Furthermore, the processes regulating endometrial remodelling and implantation, including those controlling hormonal impact, breakdown and repair, stem/progenitor cell activation, inflammation and cell invasion have broad applications to other fields. This Review presents current knowledge regarding the normal and abnormal function of the human endometrium. The development of biomarkers for prediction of uterine diseases and pregnancy disorders and future avenues of investigation to improve fertility and enhance endometrial function are also discussed.

Effects of metformin on endocrine, metabolic milieus and endometrial expression of androgen receptor in patients with polycystic ovary syndrome

OBJECTIVE

To evaluate effects of metformin on endocrine, metabolic parameters and endometrial androgen receptor (AR) expression in polycystic ovary syndrome (PCOS).

DESIGN

Prospective observational study.

METHODS

We analyzed blood samples from 10 PCOS patients, of whom endometrium was also analyzed in five patients. Before and after three months of metformin treatment, endocrine, glucose metabolic parameters and the endometrial AR expressions were assessed. The relative expression levels of AR were examined by immunohistochemistry.

MAIN OUTCOME MEASURES

The group post-treatment mean of homeostasis model assessment insulin resistance (HOMA-IR) for all patients was significantly lower than the pretreatment. Ovulation was restored in five out of 10 patients. The group post-treatment means of luteinizing hormone (LH) and HOMA-IR for the five ovulatory patients were significantly lower. The relative expression levels of endometrial AR were decreased in four out of the five patients as compared with pretreatment. In the four patients, one or more of the parameters, HOMA-IR, LH or free testosterone, decreased compared with pretreatment.

CONCLUSION

Metformin was effective in decreasing HOMA-IR, LH, free testosterone and the relative expression levels of AR. Furthermore, metformin might improve the systemic and local environment of the uterus caused by hyperandrogenemia in PCOS patients with insulin resistance.

First-trimester exposure to metformin and risk of birth defects: a systematic review and meta-analysis

BACKGROUND

Metformin is generally considered a non-teratogenic drug; however, only a few studies specifically designed to assess the rate of congenital anomalies after metformin use have been published in the literature. The objects of the present study were to review all of the prospective and retrospective studies reporting on women treated with metformin at least during the first trimester of their pregnancy and to estimate the overall rate of major birth defects.

METHODS

Databases were searched for English language articles until December 2013. Inclusion criteria for the meta-analysis were: a case group of women with PCOS or pre-pregnancy type 2 diabetes and first-trimester exposure to metformin; a disease-matched control group which was not exposed to metformin or other oral anti-diabetic agents; and a list of the major anomalies in both the study and the control groups. A random effects model was used for the meta-analysis of data, using odds ratios. Studies not fulfilling the inclusion criteria for the meta-analysis but reporting relevant data on major malformations in women diagnosed with PCOS were then used to estimate the overall birth defects rate.

RESULTS

Meta-analysis of nine controlled studies with women affected by PCOS detected that the rate of major birth defects in the metformin-exposed group was not statistically increased compared with the disease-matched control group and that there was no significant heterogeneity among the studies. The metformin-exposed sample was composed of 351 pregnancies and the OR of major birth defects was 0.86 (95% confidence interval: 0.18-4.08; Pheterogeneity = 0.71). By evaluating all of the non-overlapping PCOS studies reported in the literature, even those without an appropriate control group, the overall rate of major anomalies was 0.6% in the sample of 517 women who discontinued the therapy upon conception or confirmation of pregnancy and 0.5% in the sample of 634 women who were treated with metformin throughout the first trimester of their pregnancy. Regarding type 2 diabetic women, we did not identify a sufficient number of studies with metformin exposure during the first trimester to proceed with the meta-analysis.

CONCLUSIONS

There is currently no evidence that metformin is associated with an increased risk of major birth defects in women affected by PCOS and treated during the first trimester. However larger ad hoc studies are warranted in order to definitely confirm the safety and efficacy of this drug in pregnancy.

Direct effects of metformin in the endometrium: a hypothetical mechanism for the treatment of women with PCOS and endometrial carcinoma

Although a number of in vitro studies have demonstrated the antiproliferative, anti-invasive, and antimetastatic effects of metformin in multiple cancer cell types, its cellular and molecular mechanisms of anti-cancer action in the endometrium of women with polycystic ovary syndrome (PCOS) have not yet been fully elucidated. Organic cation transporters (OCTs) and multidrug and toxin extrusion proteins (MATEs) are known to be involved in metformin uptake and excretion in cells. In this article, we discuss the novel therapeutic possibilities for early-stage endometrial carcinoma (EC) in women with PCOS focusing on metformin, which might have a direct effect in the endometrium through the OCTs and MATEs. We then review the molecular mechanism(s) of the action of metformin in the endometrium and highlight possible mechanistic insights into the inhibition of cell proliferation and tumor growth and, ultimately, the reversal of early-stage EC into normal endometria in women with PCOS.

Metformin and gonadotropins for ovulation induction in patients with polycystic ovary syndrome: a systematic review with meta-analysis of randomized controlled trials

The current systematic review with meta-analysis of randomized controlled trials (RCTs) was aimed to evaluate the effects of metformin on reproductive outcomes in patients with polycystic ovary syndrome (PCOS) who receive gonadotropins for ovulation induction. After systematic review of electronic databases and websites for registration of RCTs, a total of 7 RCTs reporting data on 1023 cycles were included in the final analysis. Descriptive data showed an overall low studies' quality due to unclear sequence generation and allocation concealment, lack of blinding procedure, incomplete outcome data and several biases and/or confounders. Data synthesis showed that metformin improved live-birth (odds ratio [OR] = 1.94, 95% confidence interval [CI] 1.10 to 3.44; P = 0.020) and pregnancy (OR = 2.25, 95% CI 1.50 to 3.38; P < 0.0001) rates, without significant heterogeneity across the studies (P = 0.230, estimation of inconsistency = 30%; and P = 0.710, estimation of inconsistency = 0%, respectively, for live-birth and pregnancy rates). A significant reduction of cancellation rate was observed after metformin administration (OR = 0.41, 95% CI 0.24 to 0.72, P = 0.002) without significant heterogeneity across the studies (P = 0.500, estimation of inconsistency = 0%). Metformin administration influenced or did not influence other secondary endpoints assessed with a significant heterogeneity. In conclusion, metformin administration increases the live-birth and pregnancy rate in PCOS patients who receive gonadotropins for ovulation induction. Further well designed, blinded, placebo-controlled, and adequately powered RCTs are need to confirm that metanalytic results.

The efficacy of metformin in pregnant women with polycystic ovary syndrome: a meta-analysis of clinical trials

OBJECTIVES

The role of metformin in the treatment of pregnant women with polycystic ovary syndrome (PCOS) is controversial. Therefore, we evaluated whether the use of metformin during pregnancy in women with PCOS could reduce pregnancy-related complications.

RESEARCH DESIGN AND METHODS

MEDLINE was searched to retrieve relevant trials. In addition, reviews and reference lists of the retrieved articles were scanned for further appropriate studies. The primary outcome measure was the incidence of complications of pregnancy, which included early pregnancy loss (EPL), gestational diabetes (GDM), pre-eclampsia (PE), and pre-term delivery (PD).

RESULTS

In total, eight studies with 1106 patients were included. The pooled odds ratio (OR) (95% confidence interval) of outcome for pregnant women with PCOS prescribed metformin were 0.32 (0.19-0.55) for EPL, 0.37 (0.25-0.56) for GDM, 0.53 (0.30-0.95) for PE and 0.30 (0.13-0.68) for PD.

CONCLUSIONS

Metformin therapy throughout pregnancy decreased the OR of EPL, GDM, PE, and PD in pregnant PCOS women with no serious detrimental side effects.

Metformin reduces the expression of corticotropin-releasing hormone and urocortin in the endometrium of healthy women

OBJECTIVE

To investigate the effect of metformin administration on the expression of endometrial corticotrophin-releasing hormone (CRH) and urocortin (UCN) in the midluteal phase of the cycle.

DESIGN

Experimental study, performed in 2010-2011.

SETTING

University hospital.

PATIENT(S)

Eight healthy, normally cycling and parous women volunteered for the study.

INTERVENTION(S)

All women were investigated in two nonconsecutive cycles (control cycle, untreated and after one cycle break; trial cycle, oral administration of metformin [850 mg × 2]). Endometrial pipelle biopsies were obtained on day LH+7.

MAIN OUTCOME MEASURE(S)

The endometrial biopsies were immunohistochemically assessed for CRH and UCN expression. Evaluation of positivity was performed by applying the immunoreactive score.

RESULT(S)

Compared with samples from control cycles, CRH and UCN were significantly reduced in endometrial samples obtained during metformin treatment. This down-regulation was significant both in the endometrial cells and in the endometrial stroma.

CONCLUSION(S)

This is the first study showing that during the midluteal phase of the cycle, metformin may decrease the production of CRH and UCN in the endometrium. Metformin interference to decidualization could happen by CRH/UCN modification.

Birth weight and childhood growth in daughters of women with irregular menstrual cycles

Menstrual irregularity has been associated with insulin resistance, type 2 diabetes mellitus and markers of metabolic dysfunction. This study aimed to determine whether irregular menstrual cycles (MCs) in reproductive-age women are associated with the weight of their daughters at birth and growth up to age five. We studied 4863 pregnant women with menstrual history data in a prospective cohort, recruited from the Kaiser Health Plan (1959-1966). Serial measures of their daughters' weight and height were abstracted from medical records. We used analysis of covariance, stratified by maternal body mass index, to explore the association between maternal MC and infant birth weight (BW). We included 4774 daughters in a repeated measures analysis to compare the effect of maternal MC on childhood weight through age five. Daughters of non-obese women with irregular MC had a statistically significant lower BW compared to daughters of women with regular MC; this difference was notably amplified among obese women. The daughters' weights were not statistically different when growth was assessed from birth to five years. We conclude that daughters of obese women with irregular MC, in particular, had significantly lower BW compared to daughters of women with regular MC, which did not persist over five years of follow-up.

Effect of metformin treatment on endometrial vascular indices in anovulatory obese/overweight women with polycystic ovarian syndrome using three-dimensional power doppler ultrasonography

PURPOSE

Metformin has been shown to be an effective treatment for anovulatory polycystic ovary syndrome (PCOS) patients in terms of menstrual cyclicity, ovulation, and pregnancy, as well as reduction of early miscarriage rate. The aim of the study is to assess the effect of metformin on the endometrial vascular indices in anovulatory obese PCOS women using three-dimensional power Doppler sonography (3DPDUS).

METHODS

A prospective study was set to determine the beneficial effects of metformin on PCOS patients. Fifty anovulatory obese PCOS patients were compared with another 50 healthy volunteers who were age- and body mass index-matched (control group). PCOS patients were treated with metformin (Glucophage; MerckSerono) 850 mg 3 times a day for 6 months. Assessment of the endometrial thickness and volume, uterine Doppler indices, and Doppler vascular indices of the endometrium and subendometrium in the periovulatory and midluteal phases were performed with 3DPDUS.

RESULTS

There was a significant increase in the endometrial thickness, endometrial volume, and endometrial and subendometrial vascularity indices (vascularization index, flow index, vascularization flow index) after 6 months of metformin treatment in PCOS women, whereas there was no change in the resistance index and the pulsatility index of the uterine artery in both periovulatory and midluteal phases.

CONCLUSIONS

Metformin, owing to its metabolic, endocrine, vascular, and anti-inflammatory effects, improves markers of endometrial receptivity.

Metformin augments the levels of molecules that regulate the expression of the insulin-dependent glucose transporter GLUT4 in the endometria of hyperinsulinemic PCOS patients

STUDY QUESTION

Does treatment with the insulin sensitizer metformin modify the levels and activation of proteins related to the expression of the insulin-dependent glucose transporter (GLUT4), such as adenosine monophosphate-activated protein kinase (AMPK) and myocyte enhancer factor 2A (MEF2A), in endometria from hyperinsulinemic hyperandrogenemic polycystic ovary syndrome (PCOS h-Ins) patients?

SUMMARY ANSWER

In PCOS h-Ins patients, metformin increases endometrial levels of GLUT4 mRNA and protein levels by normalizing the quantity and activation of molecules that regulate GLUT4 expression to healthy values. These changes could improve endometrial metabolic function.

WHAT IS ALREADY KNOWN

PCOS is an endocrine-metabolic disorders closely associated with insulin resistance. In particular, the insulin signaling pathway is impaired in endometria from these patients and the concentration of GLUT4, as well as the molecules involved in its translocation to the cell surface, is decreased. However, there are limited data about the mechanisms that regulate the GLUT4 expression in the endometria and the effect of metformin on them.

STUDY DESIGN, SIZE AND DURATION

This is a case-control study in the setting of a research unit, approved by the Ethical Committees of our institution. The groups whose endometria were studied were PCOS h-Ins (n = 8); PCOS patients with hyperandrogenemia hyperinsulinemia taking only metformin for at least 3 months (PCOS-MTF, n = 8) and healthy fertile women at the time of hysterectomy because of benign pathology as controls (CE, n = 8).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Steroids and sex hormone-binding globulin were measured and glucose and insulin levels were evaluated during an oral glucose tolerance test. Protein levels for αAMPK (catalytic subunit of AMPK), phosphorylated (p)-AMPKαThr(172) (activating phosphorylation site), MEF2A, p-MEF2AThr312 (activating phosphorylation site) and GLUT4 were assessed by western blot and immunohistochemistry. In addition, GLUT4 gene expression was evaluated by RT-PCR.

MAIN RESULTS AND THE ROLE OF CHANCE

We found significantly lower levels of MEF2A and p-MEF2AThr312 in PCOS h-Ins compared with CE endometria (P < 0.05). Also, we detected lower levels of p-AMPKαThr(172) in PCOS h-Ins endometria compared with the PCOS-MTF group (P < 0.05). The ratios of phospho-AMPK/total AMPK and phospho-MEF2A/total MEF2A were significantly increased in the PCOS-MTF compared with the PCOS h-Ins group (P < 0.05). The RT-PCR experiments showed lower levels of GLUT4 mRNA transcripts in PCOS h-Ins compared with PCOS-MTF-treated group (P < 0.05), the protein levels of GLUT4 were decreased in a similar way.

LIMITATIONS, REASONS FOR CAUTION

The limited number of patients included in this study who presented large clinical variability. Therefore, it would be necessary to recruit a greater number of patients to minimize our data dispersion in order to prove the clinical benefits of metformin described by others.

WIDER IMPLICATIONS OF THE FINDINGS

Since the insulin sensitizer metformin increases the expression of the GLUT4, it may improve endometrial physiology in PCOS patients and, therefore, promote better reproductive outcomes. These results suggest that in PCOS patients, metformin may act directly at the endometrial level and decrease insulin resistance condition by increasing the expression of GLUT4 and, in this way, indirectly restore endometrial function.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by Fondo Nacional de Desarrollo Científico y Tecnológico (grant number 1095127 to M.V.). None of the authors has any conflict of interest to declare.

Metformin modulates IL-8, IL-1β, ICAM and IGFBP-1 expression in human endometrial stromal cells

To evaluate the effects of metformin on endometrial stromal cell gene expression and on the decidualization process, endometrial biopsies were collected from five healthy, regularly cycling women. Stromal cell culture was performed and decidualized with oestrogen/progesterone in the presence or absence of metformin and thereafter stimulated with insulin. The effect of metformin on decidualization was analysed by prolactin determination in the cell culture supernatant. Gene expression of insulin-like growth factor binding protein 1 (IGFBP-1), interleukin (IL) 8 and 1β and intercellular adhesion molecule (ICAM) was analysed by real-time PCR. Decidualization was significantly diminished in cells incubated with metformin (P<0.05) accompanied by a significant reduction of prolactin secretion in the supernatant (day 10: 2.2 fold, P<0.05; day 15: 3.1 fold, P<0.05). IGFBP-1 gene expression was reduced after long-term metformin exposure (7.7 fold, P<0.05). The negative effect of insulin on IL-8 (4.8 fold) and IL-1β (9.3 fold) gene expression was similarly found in cells incubated with metformin. As far as is known, this is the first demonstration of a change in endometrial gene and protein expression after in-vitro stimulation with metformin, including a diminished decidualization process and changes in genes relevant to implantation.

Use of metformin in the treatment of polycystic ovary syndrome

Metformin is quite an old drug, but it is optimal for the control of glycemia in Type 2 diabetes. It was reported, 15 years ago, that insulin resistance was abnormally high in most polycystic ovary syndrome (PCOS) patients. Starting from that moment, increasing numbers of studies were performed to demonstrate the efficacy of metformin in controlling and/or modulating several aspects of PCOS, which is the most common cause of menstrual irregularity, inesthetisms and infertility. Metformin induces higher glucose uptake, thus inducing a lower synthesis/secretion of insulin. Such an effect permits the possible restoration of the normal biological functions that are severely affected by the compensatory hyperinsulinemia reactive to the increased peripheral insulin resistance. These are the basis of the many positive effects of this drug, such as the restoration of menstrual cyclicity, ovulatory cycles and fertility, because abnormal insulin levels affect the hypothalamus-pituitary-ovarian function, as well as the use of glucose in peripheral tissues. Metformin improves the impairments typically observed in hyperinsulinemic PCOS patients, reducing the possible evolution towards metabolic syndrome and Type 2 diabetes; and when pregnancy occurs, it consistently reduces the risk of gestational diabetes, eclampsia and hypertension. PCOS seems to be the perfect physiopathological condition that might have higher benefits from metformin administration, obviously after Type 2 diabetes. This review focuses on the many aspects of PCOS and on the possible issues of this disease for which metformin might be a putative optimal treatment.

Report of the international symposium: polycystic ovary syndrome: first Latin-American consensus

During the last years, numerous consensuses have been held in different countries in order to review the data concerning diagnosis and treatment and their relationship with the ethnic origin, social status and lifestyle of women with Polycystic Ovary Syndrome (PCOS). This study describes the conclusions concerning diagnostic criteria and the appropriate treatment of women with PCOS reached during the International Symposium Polycystic Ovary Syndrome, First Latin-American Consensus held in Buenos Aires, Argentina on 4th and 5th May 2009 to be applied in South American.

Polycystic Ovary Syndrome: Update on Treatment Options and Treatment Considerations for the Future

Polycystic ovary syndrome is an endocrine disorder characterized by insulin resistance, hyperandrogenemia, obesity, and inflammation, and is the most common cause of infertility. Women with PCOS are at higher risk than non-PCOS women for diabetes, cardiovascular disease, endometrial cancer, and psychiatric disorders. Because many abnormalities present in PCOS and symptoms vary considerably among PCOS women, treatment is guided by presentation and does not consist of simply one modality. Often, however, one type of medication can ameliorate more than one abnormality in PCOS. This review summarizes current research on several treatment modalities for PCOS, including drugs that are fairly well-established as efficacious and other agents that may prove efficacious in the future, with particular emphasis on the benefits and barriers of lifestyle change.

Role of metformin in the management of polycystic ovary syndrome

Polycystic ovary syndrome is the most common endocrinological disorder affecting 4-12% of women and also the most controversial. Metformin was logically introduced to establish the extent to which hyperinsulinaemia influences the pathogenesis of the condition. Early studies were very encouraging. Randomized controlled studies and several metaanalyses have changed the picture and put the drug that was once heralded as magic in a much contracted place. More work is needed to establish its right place in particular with regards to the prevention of many gestational and long-term complications.

Laparoscopic ovarian diathermy vs clomiphene citrate plus metformin as second-line strategy for infertile anovulatory patients with polycystic ovary syndrome: a randomized controlled trial

OBJECTIVE

The purpose of this study was to compare the effectiveness of laparoscopic ovarian diathermy (LOD) vs clomiphene citrate (CC) plus metformin in infertile patients with CC-resistant polycystic ovary syndrome (PCOS).

STUDY DESIGN

Fifty primary infertile patients with CC-resistant PCOS were assigned randomly to receive LOD followed by a 6-month observation (group A) or 6-cycle course of CC plus metformin (group B). Reproductive and safety outcomes were analyzed.

RESULTS

No significant difference between 2 groups in pregnancy (15/92 women [16.3%] vs 14/107 women [13.1%]; P = .521) and live-birth (13/92 women [14.1%] vs 12/107 women [11.2%]; P = .536) rates per cycle was observed. With the use of a Cox regression analysis, patients under medical treatment, compared with patients who received surgical treatment, had a relative risk of pregnancy of 1.2 (95% confidence interval, 0.61-2.44; P = .582) and a relative risk of live-birth of 1.4 (95% confidence interval, 0.63-2.96; P = .425).

CONCLUSION

LOD and CC plus metformin seem to be 2 effective approaches to treat infertility in patients with CC-resistant PCOS.

Uterine blood flow in pregnant patients with polycystic ovary syndrome: relationships with clinical outcomes

OBJECTIVE

To study the impedance to blood flow through the uterine artery in pregnant women with polycystic ovary syndrome (PCOS), and to evaluate its predictive value for adverse pregnancy and perinatal outcomes in this population.

DESIGN

Prospective case-control study.

SETTING

Academic Departments of Obstetrics and Gynaecology in Italy.

POPULATION

Seventy-three pregnant women with ovulatory PCOS (PCOS group) and 73 age- and body mass index-matched healthy pregnant controls (control group).

METHODS

Serial Doppler velocimetry measurements of the uterine artery.

MAIN OUTCOME MEASURES

Blood flow impedance indices and pregnancy/perinatal outcomes.

RESULTS

A significantly (P < 0.05) higher rate of subjects with abnormal velocimetry findings was observed in the PCOS group than in the control group. In the PCOS group, the pulsatility index (PI) at first (P = 0.042) and mid-second (P = 0.039) trimesters of pregnancy, and bilateral notch at first (P = 0.025) and mid-second (P = 0.007) trimesters of pregnancy, were the strongest independent predictors of adverse outcomes. Conversely, in the control group, PI at the first trimester of pregnancy was a predictor of adverse outcomes only when combined with bilateral notch (P = 0.042), whereas at mid-second trimester of pregnancy PI (P = 0.033) and bilateral notch (P = 0.048) were independent predictors of adverse outcomes.

CONCLUSIONS

Uterine artery Doppler indices are more commonly altered in pregnant patients with PCOS than in controls, showing a high predictive value for abnormal pregnancy/perinatal outcomes.

Effect of DHEA and metformin on corpus luteum in mice

We evaluated the effect of hyperandrogenism in ovaries with functional and regressing corpora lutea (CL) and the action of metformin in preventing these possible alterations using a mouse model. To obtain a CL functional for 9+/-1 days, immature female mice of the BALB/c strain were injected i.p. with 10 IU/mouse of pregnant mare's serum gonadotropin (PMSG). DHEA (60 mg/kg body weight s.c., 24 and 48 h prior to kill) decreased both serum progesterone (P) and estradiol (E(2)) levels and increased the activity of superoxide dismutase (SOD) from ovaries with functional CL (on day 5 after PMSG). It increased P and E(2) and the activities of SOD and catalase (CAT) and decreased lipoperoxidation of ovaries with regressing CL (on day 9 after PMSG). Treatment with DHEA did not affect the production of prostaglandin F(2alpha) (PGF(2alpha)) or PGE by ovaries with functional CL, whereas DHEA decreased PGF(2alpha) and increased PGE production by ovaries with regressing CL. Metformin (50 mg/kg body weight, orally) given together with DHEA restored E(2) levels from mice with ovaries with functional CL and serum P, PGF(2alpha) and PGE levels, and oxidative balance in mice with ovaries with regressing CL. Metformin alone was able to modulate serum P and E(2) levels, lipoperoxidation, SOD and CAT, and the 5,5-dimethyl-1-pyrroline N-oxide/(*)OH signal. These findings suggest that hyperandrogenism is able to induce or to rescue CL from luteolysis and metformin treatment is able to prevent these effects.

Effects of metformin on mammalian target of rapamycin in a mouse model of endometrial hyperplasia

OBJECTIVE

The effects of metformin on S6K1, which is a crucial effector of mTOR signaling, and on endometrium were studied in a mouse model of endometrial hyperplasia induced by unopposed estradiol or tamoxifen.

STUDY DESIGN

Forty-eight oophorectomized Balb/c mice were randomly assigned to receive saline, tamoxifen citrate (4 mg/kg), 17-beta estradiol hemihydrate (4 mg/kg), metformin (50 mg/kg), tamoxifen citrate (4 mg/kg) with metformin (50 mg/kg), or estradiol (4 mg/kg) with metformin (50 mg/kg) for 3 days. Histological markers of uterotrophy, including luminal epithelial cell height and density of endometrial glands were quantified for each slide. Immunohistochemical expression of PCNA and S6K1 was evaluated. H-score was used for S6K1 expression. Statistical analysis was performed using Student's t-test for comparison of two continous variables and one-way ANOVA for comparison of multiple variables.

RESULTS

Mice treated either with tamoxifen or estradiol had significantly increased density of endometrial glands and epithelial heights compared to vehicle-only or metformin-only group (p<0.001). Addition of metformin to tamoxifen or estradiol treated mice significantly decreased the density of endometrial glands and epithelial cell heights (p<0.05). Addition of metformin to tamoxifen significantly decreased the H-score of S6K1 (p<0.05) and the immunohistochemical expression of PCNA (p<0.05) in uterine lining epithelium, glandular and stromal cells. Addition of metformin to estradiol significantly decreased the H-score of S6K1 (p<0.05) and the immunohistochemical expression of PCNA (p<0.05) in uterine lining epithelium, glandular and stromal cells.

CONCLUSION

Metformin seems to have possible antiproliferative effects on the endometrium of estradiol or tamoxifen treated mice via inhibiting the mTOR mediated S6K1 activation.

A role for menstruation in preconditioning the uterus for successful pregnancy

Menstruation is widely viewed as serving no purpose other than to reinitiate the endometrial cycle in the absence of pregnancy. Yet, it is striking that cyclic endometrial decidualization followed by menstrual shedding is confined to the few species, including human beings, where placenta formation entails deep trophoblast invasion of maternal tissues and its vasculature. Both menstruation and pregnancy are inflammatory conditions that cause a degree of physiological ischemia-reperfusion tissue injury, albeit much more so in pregnancy. Thus, the emergence of cyclic menstruation may not have been an evolutionary coincidence but serves to protect uterine tissues from the profound hyperinflammation and oxidative stress associated with deep placentation, a process known as preconditioning. The concept of menstrual preconditioning provides a novel paradigm for understanding how reproductive disorders impact on pregnancy outcome. For example, endometriosis could be viewed as a disorder of exaggerated menstrual preconditioning that confers protection against placentation-related disorders, such as preeclampsia.

The effects of metformin on uterine tissue of hyperandrogenized BALB/c mice

The present study investigated the role of the N, N'-dimethylbiguanide metformin (50 mg/kg body weight in 0.05 ml water, given orally with a canulla) in preventing the adverse effects generated by hyperandrogenism on uterine function. Daily injection of dehydroepiandrosterone (DHEA: 6 mg/100 g body weight in 0.1 ml oil) for 20 consecutive days induces polycystic ovaries in BALB/c mice. In this model we found that DHEA produced alterations on uterine histology closely related to the development of pre-cancerous structures concomitantly with increased incidence of uterine apoptosis. The injection of DHEA induced a pro-inflammatory status since uterine prostaglandin (PG) F2 alpha levels and cyclooxygenase 2 were increased although PGE levels were decreased. Furthermore, DHEA promoted a pro-oxidant status since it increased nitric oxide synthase (NOS) activity and decreased superoxide dismutase and catalase activities and the antioxidant metabolite glutathione levels. DHEA also regulated the percentages of CD4+ and CD8+ T lymphocyte that infiltrate uterine tissue. When metformin was administered together with DHEA uterine histology and apoptosis did not differ when compared with controls. Therefore, metformin prevented the pro-inflammatory and pro-oxidative status generated by DHEA and restores the ratios of CD4+ and CD8+ T cells to those observed in controls. We conclude that metformin is able to restore either directly or indirectly uterine function by preventing some inflammatory and oxidative alterations produced by hyperandrogenism.

Effects of testosterone and metformin on glucose metabolism in endometrium

OBJECTIVE

To investigate the effects of testosterone and metformin on glucose metabolism in endometrium.

DESIGN

In vitro experiment.

SETTING

Reproductive and Genetic Center, Obstetrics and Gynecology, The First Hospital of Peking University, Beijing, China.

PATIENT(S)

Premenopausal women undergoing total abdominal hysterectomy for uterine myoma or adenomyosis.

INTERVENTION(S)

Endometrial glandular epithelial cell culture.

MAIN OUTCOME MEASURE(S)

Insulin receptor substrate-1 (IRS-1) and glucose transporter 4 (GLUT-4) expression in endometrial glandular epithelial cell.

RESULT(S)

After the action of testosterone solution, the protein expressions of IRS-1mRNA, IRS-1, and GLUT-4 in endometrial glandular epithelial cells all decreased significantly. Metformin may reverse this effect.

CONCLUSION(S)

The high androgen levels in patients with polycystic ovary syndrome could induce insulin resistance in endometrial glandular epithelial cell, whereas metformin has an antagonizing effect.

Clomiphene citrate, metformin or both as first-step approach in treating anovulatory infertility in patients with polycystic ovary syndrome (PCOS): a systematic review of head-to-head randomized controlled studies and meta-analysis

BACKGROUND

To date, no systematic review or meta-analysis has been published of direct head-to-head studies comparing clomiphene citrate (CC) vs. metformin, or the combination of both drugs as first-line therapy in anovulatory polycystic ovary syndrome (PCOS) patients seeking pregnancy. The aim of the current paper was to define, if possible, the best evidence-based recommendations regarding the use of CC and/or metformin as the initial treatment of PCOS women with anovulatory infertility.

DESIGN

Systematic review and meta-analysis of the head-to-head randomized controlled trials (RCTs) available in the literature.

METHODS

A bibliographic search was performed using the following bibliographic databases: Medline, EMBASE, Biological Abstracts, Cochrane Controlled Trials Register and Cochrane Database of Systematic Reviews. Reference lists of included studies, other relevant review articles and textbooks were checked for additional citations of interest.

RESULTS

Four head-to-head RCTs were identified and qualified for inclusion in the analysis. No difference in fertility improvement was observed comparing CC with metformin (OR = 1.22, 95% CI 0.23-6.55, P = 0.815), whereas a significant (P < 0.0001) heterogeneity was observed. Homogeneous data showed no difference in fertility improvement between the combination treatment and CC monotherapy (OR = 0.99, 95% CI 0.70-1.40, P = 0.982), but a significant difference in comparison with metformin monotherapy (OR = 0.23, 95% CI 0.14-0.37, P < 0.0001).

CONCLUSIONS

In PCOS patients with anovulatory infertility and not previously treated, the administration of metformin plus CC is not better than monotherapy (metformin alone or CC alone), whereas to date no specific recommendation can be given regarding the use of CC or metformin as first-step drug.

Evidence-based and potential benefits of metformin in the polycystic ovary syndrome: a comprehensive review

Metformin is an insulin sensitizer widely used for the treatment of patients affected by type 2 diabetes mellitus. Because many women with polycystic ovary syndrome (PCOS) are insulin resistant, metformin was introduced in clinical practice to treat these patients also. Moreover, metformin's effect has other targets beside its insulin-sensitizing action. The present review was aimed at describing all evidence-based and potential uses of metformin in PCOS patients. In particular, we will analyze the uses of metformin not only for the treatment of all PCOS-related disturbances such as menstrual disorders, anovulatory infertility, increased abortion, or complicated pregnancy risk, hyperandrogenism, endometrial, metabolic and cardiovascular abnormalities, but also for the prevention of the syndrome.

Use of metformin in polycystic ovary syndrome

Women with polycystic ovary syndrome (PCOS) have a myriad of phenotypic and clinical features that may guide therapeutic options for metabolic protection and ovulation induction. The use of metformin may prove beneficial in a subset of the population of women with PCOS. Hyperinsulinemia, as demonstrated by elevated insulin levels on a 2-hour 75-g load glucose tolerance test, is an important parameter in deciding whether or not to initiate metformin therapy to women with PCOS with the hope of preventing or delaying the onset of type 2 diabetes mellitus (DM). Cardiovascular risk factors including markers of subclinical inflammation, and dyslipidemia may also be improved by metformin therapy. For ovulation induction, metformin is not as effective as clomiphene citrate as first-line therapy for women with PCOS. There are no clear data to suggest that metformin reduces pregnancy loss or improves pregnancy outcome in PCOS, and it is currently recommended that metformin be discontinued with the first positive pregnancy test result, unless there are other medical indications (eg, type 2 DM). This review addresses practical management guidelines for the uses of metformin in women with PCOS.

[Color Doppler imaging and measurements of intraovarian and intrauterine vascularization on basal ultrasound examination in spontaneous ovulatory and anovulatory cycles]

BACKGROUND/AIM

Any organs functioning directly depends on vascularization. It applies also to the uterus and ovary which go through changes of vascularization during a menstruation cycle. The aim of this investigation was to determine differences in intrauterine and ovarian stromal arterioral blood flow on basal ultrasound examination (day 2-4) between spontaneous ovulatory and anovulatory cycles.

METHODS

This prospective clinical investigation included 205 patients divided into two groups: with ovulatory and with anovulatory cycles.

RESULTS

Resistance to ovarian arterioral stromal blood flow was significantly lower in the patients with ovulatory cycles (pulsatile index--PI 0.97 +/- 0.4 vs 1.93 +/- 1.37; p = 0.001737; and (resistance index - RI 0.55 +/- 0.12 vs 0.68 +/- 0.14; p = 0.040033). There. were no statistically significant differences in arcuate arterioral blood flow in the pateints with ovulatory and anovulatory cycles (PI 1.21 +/- 0.34 vs 61 +/- 0,61 p = 0.136161 and RI 0.64 +/- 0.11 vs 0.74 +/- 0.07; p = 0.136649). The patients with ovulatory cycles had lower uterine radial arterioral blood flow than the patients with anovulatory cycles (PI 1.001 +/- 0.22 vs 1.61 +/- 0.23 p = 0.007501 and RI 0.55 +/- 0.08 vs 0.71 +/- 0.12; p = 0,0460113). The patients with ovulatory cycles had lower subendometrial arterioral blood flow resistance (PI 0.69 0.19 vs 1.385 +/- 0.09; p = 0.00622 and RI 0.44 +/- 0.09 vs 0.65 +/- 0.02; p = 0.027458).

CONCLUSION

Color Doppler ultrasuond imaging and measurements of intrauterine and ovarian stromal arterioral blood flow on basal ultrasound examination (day 2-4), showed lower resistance to blood flow in ovulatory than in anovulatory cycles.

Effect of preconceptional metformin on abortion risk in polycystic ovary syndrome: a systematic review and meta-analysis of randomized controlled trials

OBJECTIVE

To evaluate the effect of pregestational metformin administration on abortion risk in polycystic ovary syndrome (PCOS) patients.

DESIGN

Systematic review and meta-analysis.

SETTING

Academic Department of Obstetrics and Gynecology in Italy.

PATIENT(S)

Women affected by PCOS receiving pregestational metformin.

INTERVENTION(S)

Systematic review of randomized controlled trials (RCTs) published up to June 2008 and subsequent meta-analysis.

MAIN OUTCOME MEASURE(S)

Abortion rate.

RESULT(S)

Seventeen RCTs were included in the final analysis. Overall, no effect of the metformin administration was detected on the abortion risk. No statistically significant effect of metformin on the abortion risk was observed in any comparison when subgrouping the RCTs according to received treatment.

CONCLUSION(S)

Metformin has no effect on the abortion risk in PCOS patients when administered before pregnancy.

Polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is the most common female endocrinopathy, affecting 5-10% of the female population. It involves overproduction of ovarian androgens leading to a heterogeneous range of symptoms including hirsutism, acne, anovulation and infertility. Hyperinsulinaemia, exacerbated by obesity, is often a key feature. Treatment depends on the presenting symptoms, which may often be ameliorated by weight loss where relevant. Anti-androgen preparations are used for hyperandrogenic symptoms, and clomiphene citrate (CC) is the first-line treatment for anovulation and infertility. Aromatase inhibitors are being investigated as an alternative to CC. Failure to conceive with CC can be treated in a number of ways, including the addition of insulin-lowering agents (mainly metformin), low-dose gonadotrophin therapy or surgically by laparoscopic ovarian drilling. Although the exact aetiology of PCOS is not known, the therapeutic alternatives provide reasonably successful symptomatic treatment.

Clomiphene citrate versus metformin as first-line approach for the treatment of anovulation in infertile patients with polycystic ovary syndrome

CONTEXT

Clomiphene citrate (CC) and metformin are two effective drugs used to induce ovulation in patients with polycystic ovary syndrome (PCOS), even if it is still unclear which compound between them should be initially administered.

OBJECTIVE

The aim of the study was to compare in a clinical setting the efficacy of CC and metformin as first-line approaches for treating anovulation in infertile PCOS patients.

DESIGN

This study was a multicenter, nonrandomized, prospective, controlled study.

SETTING

The study was conducted at the Department of Obstetrics and Gynecology, Universities "Magna Graecia" of Catanzaro and "Federico II" of Naples, Italy.

PATIENTS

Patients included 80 infertile anovulatory patients with PCOS allocated in two body mass index- and age-matched groups (experimental and control groups).

INTERVENTIONS

Six months of 1700 mg/d metformin treatment (experimental group) or CC was administered using a traditional incremental-dose protocol (control group). In both groups, patients who ovulated under treatment continued the therapy for a total of 6 months.

MAIN OUTCOME MEASURES

Reproductive outcomes were measured.

RESULTS

Experimental and control groups were studied for a total of 204 and 169 cycles, respectively. No difference between the two groups was observed in ovulation (55.4 vs. 59.8%, respectively; P = 0.396), pregnancy (10.8 vs. 11.2%, respectively; P = 0.888), and abortion (19.5 vs. 26.3%, respectively; P = 0.530) rates. The cumulative pregnancy rate was not different between groups (62.9 vs. 48.6%, respectively; P = 0.225).

CONCLUSION

A 6-month course of 1700 mg/d metformin treatment and CC administered in an escalation protocol are two effective first-line approaches for improving fertility in anovulatory PCOS women.

Le syndrome des ovaires polykystiques (SOPK)

Polycystic ovaries syndrome (PCOS) is one of the most common female hormonal disorders. Its multiple components--reproductive, metabolic, neoplasic and cardiovascular--have a major impact on the public health. Androgen excess and resistance to insulin, probably from genetic origin, are responsible for most of the clinical symptomatology. Resistance to insulin seems to be accompanied by a greater risk of glucose intolerance, type 2 diabetes, lipidic anomalies and can involve the development of cardiovascular diseases. In addition, sleep apnea syndrome is more progressively described in PCOS. Infertility, menses disorders and hirsutism often push these patients to consult their physician. A better understanding of the physiopathological mechanisms led to the emergence of new therapeutic options increasing the sensitivity to insulin. Besides the pregnancy wishes, cares aim to attenuate the marks of the hyper-androgenism (hormonal treatment and cosmetic) and to correct cardiovascular, respiratory and gynaecological risk factors. In case of infertility by anovulation, cares must be performed by trained experts to minimize the risk of ovarian hyper-stimulation syndrome and multiple pregnancies. A gradation from loose weight to clomiphene citrate ovulation induction, ovarian drilling, low dose gonadotropin, in vitro fertilisation, or in vitro maturation of oocytes should bring back good reproduction potential.