Thiazolidinediones and Fertility in Polycystic Ovary Syndrome (PCOS)

The Pathophysiological Mechanism and Clinical Treatment of Polycystic Ovary Syndrome: A Molecular and Cellular Review of the Literature

Polycystic ovary syndrome (PCOS) is a prevalent metabolic disorder among women of reproductive age, characterized by hyperandrogenism, ovulatory dysfunction, and polycystic ovaries. The pathogenesis of PCOS involves a complex interplay of genetic and environmental factors, including insulin resistance (IR) and resultant hyperinsulinemia. Insulin receptors, primarily in skeletal muscle, liver, and adipose tissue, activate downstream signaling pathways like PI3K-AKT and MAPK-ERK upon binding. These pathways regulate glucose uptake, storage, and lipid metabolism. Genome-wide association studies (GWASs) have identified several candidate genes related to steroidogenesis and insulin signaling. Environmental factors such as endocrine-disrupting chemicals and lifestyle choices also exacerbate PCOS traits. Other than lifestyle modification and surgical intervention, management strategies for PCOS can be achieved by using pharmacological treatments like antiandrogens, metformin, thiazolidinediones, aromatase inhibitor, and ovulation drugs to improve insulin sensitivity and ovulatory function, as well as combined oral contraceptives with or without cyproterone to resume menstrual regularity. Despite the complex pathophysiology and significant economic burden of PCOS, a comprehensive understanding of its molecular and cellular mechanisms is crucial for developing effective public health policies and treatment strategies. Nevertheless, many unknown aspects of PCOS, including detailed mechanisms of actions, along with the safety and effectiveness for the treatment, warrant further investigation.

Comparative efficacy of exercise, diet and/or pharmacological interventions on BMI, ovulation, and hormonal profile in reproductive-aged women with overweight or obesity: a systematic review and network meta-analysis

BACKGROUND

The increasing prevalence of obesity worldwide poses a significant threat to reproductive function owing, in part, to hormonal disturbances caused by negative feedback between excess adiposity and the hypothalamic-pituitary-ovarian axis. Consequently, finding the most appropriate strategies to lose weight and improve ovulation in women with overweight or obesity is a clinically relevant matter that needs to be investigated. A comprehensive comparison of the independent and combined efficacy of lifestyle and/or pharmacological interventions on BMI, ovulation, and hormonal profile in women with overweight or obesity at risk of anovulatory infertility would facilitate improving fertility strategies in this population.

OBJECTIVE AND RATIONALE

This study aimed to evaluate the comparative efficacy of exercise, diet, and pharmacological interventions on BMI, ovulation, and hormonal profile in reproductive-aged women with overweight or obesity.

SEARCH METHODS

A systematic review was performed by searching PubMed, Scopus, Web of Science, PsycINFO, and Cochrane Library up to 14 December 2023, for randomized controlled trials assessing the effects of exercise, diet and/or pharmacological interventions (i.e. weight-lowering drugs or ovulation inducers) on BMI, ovulation, and/or hormonal profile in reproductive-aged women with overweight or obesity. We performed frequentist random-effect network meta-analyses and rated the certainty of the evidence. The primary outcomes were BMI and ovulation rate, and the secondary outcomes were serum reproductive hormone levels (gonadotrophins, androgens, or oestrogens). We performed sensitivity analyses, including the studies that only involved women with PCOS.

OUTCOMES

Among 1190 records screened, 148 full texts were assessed for eligibility resulting in 95 trials (9910 women), of which 53% presented a high or unclear risk of bias. The network meta-analyses revealed that, compared to control: diet combined with weight-lowering drugs (mean difference (MD) -2.61 kg/m2; 95% CI -3.04 to -2.19; τ2 = 0.22) and adding exercise (MD -2.35 kg/m2; 95% CI -2.81 to -1.89; τ2 = 0.22) led to the greatest decrease in BMI; exercise combined with diet and ovulation inducers (risk ratio (RR) 7.15; 95% CI 1.94-26.40; τ2 = 0.07) and exercise combined with diet and weight-lowering drugs (RR 4.80; 95% CI 1.67-13.84; τ2 = 0.07) produced the highest increase in ovulation rate; and exercise combined with diet and weight-lowering drugs was the most effective strategy in reducing testosterone levels (standardized mean difference (SMD) -2.91; 95% CI -4.07 to -1.74; τ2 = 2.25), the third most effective strategy in increasing sex hormone-binding globulin levels (SMD 2.37; 95% CI 0.99-3.76; τ2 = 2.48), and it was coupled with being ranked first in terms of free androgen index reduction (SMD -1.59; 95% CI -3.18 to 0.01; τ2 = 1.91). The surface under the cumulative ranking curve scores suggested that: diet combined with weight-lowering drugs is the strategy most likely (94%) to produce the highest BMI reduction; and exercise combined with diet and ovulation inducers is the strategy most likely (89%) to produce the highest ovulation rate improvement. The sensitivity analyses, which exclusively included studies involving women diagnosed with PCOS, were consistent with the results presented above.

WIDER IMPLICATIONS

Overall, the findings of this network meta-analysis indicate that the combination of exercise, diet, and pharmacological interventions is effective for weight loss, improving ovulation, and normalizing the androgen levels of women with overweight or obesity. Although higher quality studies are needed, these results support that the optimal treatment strategy for women with overweight or obesity wishing to conceive must consider exercise, diet, and pharmacological interventions during the shared decision-making process.

The Effect of Thiazolidinediones in Polycystic Ovary Syndrome: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

INTRODUCTION

Polycystic ovary syndrome (PCOS) is a complex endocrine condition affecting women of reproductive age. It is characterised by insulin resistance and is a risk for type 2 diabetes mellitus (T2DM). The aim of this study was to review the literature on the effect of pioglitazone and rosiglitazone in women with PCOS.

METHODS

We searched PubMed, MEDLINE, Scopus, Embase, Cochrane Library and the Web of Science in April 2020 and updated in March 2023. Studies were deemed eligible if they were randomised controlled trials (RCTs) reporting the effect of pioglitazone and rosiglitazone in PCOS. The study follows the 2020 Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Two reviewers independently extracted data and assessed the risk of bias using the Cochrane risk of bias tool.

RESULTS

Out of 814 initially retrieved citations, 24 randomised clinical trials (RCTs) involving 976 participants were deemed eligible. Among women with PCOS, treatment with rosiglitazone compared to metformin resulted in a significant increase in the mean body weight (mean difference (MD) 1.95 kg; 95% CI 0.03-3.87, p = 0.05). Metformin treatment was associated with a reduction in mean body mass index (BMI) compared to pioglitazone (MD 0.85 kg/m2; 95% CI 0.13-1.57, p = 0.02). Both pioglitazone compared to placebo (MD 2.56 kg/m2; 95% CI 1.77-3.34, p < 0.00001) and rosiglitazone compared to metformin (MD 0.74 kg/m2; 95% CI 0.07-1.41, p = 0.03) were associated with a significant increase in BMI. Treatment with pioglitazone compared to placebo showed a significant reduction in triglycerides (MD - 0.20 mmol/L; 95% CI - 0.38 to - 0.03, p = 0.02) and fasting insulin levels (MD - 11.47 mmol/L; 95% CI - 20.20, - 2.27, p = 0.01). Rosiglitazone compared to metformin was marginally significantly associated with a reduction in the luteinising hormone (LH) (MD - 0.62; 95% CI - 1.25-0.00, p = 0.05).

CONCLUSION

Both pioglitazone and rosiglitazone were associated with significant increases in body weight and BMI when compared with metformin or placebo. Pioglitazone significantly reduced triglycerides and fasting insulin when compared with placebo while rosiglitazone showed a modest reduction of LH when compared with metformin.

PROSPERO REGISTRATION NO

CRD42020178783.

Emerging Perspectives on the Impact of Diabetes Mellitus and Anti-Diabetic Drugs on Premenstrual Syndrome. A Narrative Review

Diabetes mellitus (DM) and premenstrual syndrome (PMS) are global health challenges. Both disorders are often linked to a range of physical and psychological symptoms that significantly impact the quality of life of many women. Yet, the exact relation between DM and PMS is not clear, and the management of both conditions poses a considerable challenge. In this review, we aimed to investigate the interplay between DM, anti-diabetic drugs, and the different theories and symptoms of PMS. Female sex hormones are implicated in the pathophysiology of PMS and can also impair blood glucose control. In addition, patients with diabetes face a higher susceptibility to anxiety and depression disorders, with a significant number of patients experiencing symptoms such as fatigue and difficulty concentrating, which are reported in patients with PMS as well. Complications related to diabetic medications, such as hypoglycemia (with sulfonylurea) and fluid retention (with thiazolidinediones) may also mediate PMS-like symptoms. DM can, in addition, disturb the normal gut microbiota (GM), with a consequent loss of beneficial GM metabolites that guard against PMS, particularly the short-chain fatty acids and serotonin. Among the several available anti-diabetic drugs, those (1) with an anti-inflammatory potential, (2) that can preserve the beneficial GM, and (3) possessing a lower risk for hypoglycemia, might have a favorable outcome in PMS women. Yet, well-designed clinical trials are needed to investigate the anti-diabetic drug(s) of choice for patients with diabetes and PMS.

Preoperative Patient Evaluation: Newer Hypoglycemic Agents

New medications in the treatment of diabetes are an active area of research and drug development. Although many hypoglycemic therapies have been in use for decades, new evidence continues to emerge highlighting benefits of these medications for other indications. In this article, the authors review the classes of newer hypoglycemic agents and summarize medications currently in phase 2 and 3 clinical trials. The literature to support specific recommendations for perioperative management is scant, however, where it exists, we have included it. In other instances, the authors have noted a reasonable approach based on pharmacokinetics and principles of perioperative medication management.

Effects of different insulin sensitisers in the management of polycystic ovary syndrome: A systematic review and meta-analysis

OBJECTIVE

Characteristic features of polycystic ovary syndrome (PCOS) include insulin resistance and an increased risk for type 2 diabetes. To promote improved insulin sensitivity, insulin sensitisers have been used in PCOS. However, direct comparisons across these agents are limited. This study compared the effects of metformin, rosiglitazone and pioglitazone in the management of PCOS to inform the 2023 International Evidence-based PCOS Guideline.

DESIGN

Systematic review and meta-analysis of the literature.

PATIENTS

Women with PCOS and treatment with insulin sensitisers.

MEASUREMENTS

Hormonal and clinical outcomes, as well as side effects.

RESULTS

Of 1660 publications identified, 13 randomised controlled trials were included. Metformin was superior in lowering weight (mean difference [MD]: -4.39, 95% confidence interval [CI]: -7.69 to -1.08 kg), body mass index (MD: -0.95, 95% CI: -1.41 to -0.49 kg/m2 ) and testosterone (MD: -0.10, 95% CI: -0.18 to -0.03 nmol/L) versus rosiglitazone, whereas there was no difference when comparing metformin to pioglitazone. Adding rosiglitazone or pioglitazone to metformin did not improve metabolic outcomes. However, rosiglitazone seemed superior to metformin in lowering lipid concentrations.

CONCLUSIONS

Metformin should remain the first-line insulin sensitising treatment in adults with PCOS for the prevention and management of weight and metabolic features. The addition of thiazolidinediones appears to offer little benefit.

Adipose Tissue Dysfunction in Polycystic Ovary Syndrome

PURPOSE

Polycystic ovary syndrome (PCOS) is a complex genetic trait and the most common endocrine disorder of women, clinically evident in 5% to 15% of reproductive-aged women globally, with associated cardiometabolic dysfunction. Adipose tissue (AT) dysfunction appears to play an important role in the pathophysiology of PCOS even in patients who do not have excess adiposity.

METHODS

We undertook a systematic review concerning AT dysfunction in PCOS, and prioritized studies that assessed AT function directly. We also explored therapies that targeted AT dysfunction for the treatment of PCOS.

RESULTS

Various mechanisms of AT dysfunction in PCOS were identified including dysregulation in storage capacity, hypoxia, and hyperplasia; impaired adipogenesis; impaired insulin signaling and glucose transport; dysregulated lipolysis and nonesterified free fatty acids (NEFAs) kinetics; adipokine and cytokine dysregulation and subacute inflammation; epigenetic dysregulation; and mitochondrial dysfunction and endoplasmic reticulum and oxidative stress. Decreased glucose transporter-4 expression and content in adipocytes, leading to decreased insulin-mediated glucose transport in AT, was a consistent abnormality despite no alterations in insulin binding or in IRS/PI3K/Akt signaling. Adiponectin secretion in response to cytokines/chemokines is affected in PCOS compared to controls. Interestingly, epigenetic modulation via DNA methylation and microRNA regulation appears to be important mechanisms underlying AT dysfunction in PCOS.

CONCLUSION

AT dysfunction, more than AT distribution and excess adiposity, contributes to the metabolic and inflammation abnormalities of PCOS. Nonetheless, many studies provided contradictory, unclear, or limited data, highlighting the urgent need for additional research in this important field.

Combination therapy of curcumin and fecal microbiota transplant: Potential treatment of polycystic ovarian syndrome

Polycystic ovarian syndrome (PCOS) is a combination of various symptoms like anovulation, hirsutism, chronic amenorrhea, infertility, obesity and polycystic ovaries. It affects over 7 million women worldwide. The current strategy to treat this disorder is based on the use of drugs that provide symptomatic relief. Most of these, however, exhibit numerous side effects and are not able to ameliorate all the signs and symptoms of PCOS. As dysbiosis is considered as one of the prime underlying causes of PCOS, restoration of eubiosis was considered as a plausible way to treat it. Bacteriotherpeutics like probiotics, synbiotics and even fecal microbiota transplant (FMT) have shown considerable effectiveness in PCOS. Of these baceteriotherapeutic options, FMT is considered to be the most holistic as it encompasses the bacteriome, virome, fungome, archaeome and even parasitome while both probiotics as well as synbiotics mainly comprise bacteria. Repeated FMT, however, is not a pragmatic option because of its inconvenience, lack of standardization, involved risk and scepticism amongst patients and physicians. If the eubiosis ushered by FMT is sustained for a long time, the repeated administrations of FMT can be avoided and maintenance therapy with any agent that can maintain the eubiotic condition can be adopted. Role of curcumin on gut microbiota is widely known. It is largely attributed to the ability of certain microbes to consume polyphenols as substrates and its positive effect on bacterial consumption of nutrients such as sugars. Based on various mechanisms and studies, a new hypothesis is being proposed wherein FMT and curcumin combination is predicted to be an effective and sustained treatment of PCOS with much lower rates of remission.

Prospective associations between physical activity and BMI with irregular periods and heavy menstrual bleeding in a large cohort of Australian women

STUDY QUESTION

Are physical activity (PA) and body mass index (BMI) associated with irregular periods and heavy menstrual bleeding (HMB) in Australian women?

SUMMARY ANSWER

Overweight and obese women have higher odds of both irregular periods and HMB than underweight/normal-weight women, but high levels of PA reduce the odds of HMB.

WHAT IS KNOWN ALREADY

Most studies on relationships between PA and menstrual problems have focused on female athletes, but there have been few population-based studies.

STUDY DESIGN, SIZE, DURATION

Prospective cohort study, 10618 participants in the Australian Longitudinal Study of Women's Health (ALSWH) who completed mailed surveys in 1996, with follow-ups in 2000, 2003, 2006, 2009, 2012, and 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were aged 22 to 27 in 2000. They were asked to report their PA levels and the frequency of irregular periods and HMB in each survey. BMI was calculated at every survey from self-reported weight and height. Generalised estimating equation population-averaged model analyses were conducted to calculate odds ratios (OR) and 95% confidence intervals (95% CIs).

MAIN RESULTS AND THE ROLE OF CHANCE

At age 22 to 27 years, the prevalence of irregular periods was 19.4%. This remained stable over 15 years. There were no associations between PA and irregular periods. Overweight and obese women had higher odds of irregular periods [overweight: OR 1.08, (95% CI 1.00-1.17); obese: OR 1.29, (95%CI 1.18-1.41)] than women who were underweight/normal weight.The prevalence of HMB at age 22-27 years was 15.9%; this doubled over 15 years. Women who were highly active had 10% lower odds of HMB than women who reported no PA [OR 0.90, (95%CI 0.82-0.98)]. Overweight and obese women had higher odds of HMB [overweight: OR 1.15, (95%CI 1.07-1.23); obese: OR 1.37, (95%CI 1.26-1.49)] than women who were underweight/normal weight. Among obese women, high levels of PA were associated with 19% [OR 0.81, (95%CI 0.68-0.97)] reduction in the odds of HMB.

LIMITATIONS, REASONS FOR CAUTION

Data collected in the ALSWH are self-reported, which may be subject to recall bias. Reverse causation, due to menstrual problems impacting PA, is possible although sensitivity analyses suggest this is unlikely to have affected the results. Other conditions, e.g., polycystic ovary syndrome, for which no or incomplete data were available, could have affected the results.

WIDER IMPLICATIONS OF THE FINDINGS

Intervention studies are needed to assess the effect of increasing PA in women with HMB, but these preliminary findings suggest that promoting PA could be an affordable and feasible strategy for reducing HMB in young adult women.

STUDY FUNDING/COMPETING INTEREST(S)

The ALSWH is funded by the Australian Government. Funding for these analyses was provided by a University of Queensland (UQ) International Postgraduate Research Scholarship and a UQ International Development Fellowship. The authors declare no conflicts of interest.

TRIAL REGISTRATION NUMBER

N/A.

[Role of leptin and nuclear receptor PPARγ in PCOS pathogenesis]

Polycystic ovary syndrome (PCOS) is the most common cause of female endocrine infertility. Insulin resistanсе is supposed to be one of the essential factors of this disease pathways. At the same time, the mechanisms of PCOS development in insulin-resistant patients have not been completely established. Leptin and Peroxisome Proliferator-Activated Receptor γ(PPARγ) are involved in carbohydrate metabolism and reproduction function regulation. It indicates that leptin and PPARγ possibly play a role in the pathways of PCOS. This article is a review of publications on this issue. The purpose of this review was to systematize the available information on the molecular mechanisms that determine the role of leptin and PPARγ in the development of PCOS. The literature search was carried out from 04/05/2020 to 05/17/2020 using the scientific literature databases: NCBI PubMed (foreign sources) and Cyberleninka (domestic sources). We analyzed publications for the period 1990-2020.The review presents the current understanding of the possible role of leptin and PPARγ in the regulation of endocrine, immune systems, and reproductive function, as well as in the development of PCOS. Currently, no studies cover the mechanisms of interaction between leptin and PPARγ in the pathways of this syndrome. The available studies indicating the individual contribution and association of leptin and PPARγ with PCOS are conflicting and have many limitations. Therefore, more studies of direct and indirect interaction of leptin and PPARγ, as well as their role in PCOS pathways, are needed.

The effect of physical activity on reproductive health outcomes in young women: a systematic review and meta-analysis

BACKGROUND

In the context of increasing rates of overweight and obesity in young adult women, and the increasing numbers of women seeking help for fertility problems, it is important to understand whether physical activity (PA) could help with management of reproductive health problems, with or without weight loss.

OBJECTIVE AND RATIONALE

The primary aim of this systematic review and meta-analysis was to assess the effects of PA on selected reproductive health outcomes in young adult women, in order to inform best practice advice for women in terms of promoting fertility and reproductive health in young adulthood.

SEARCH METHODS

An electronic search of PubMed, EMBASE, MEDLINE, Cumulative Index to Nursing and Allied Health Literature, PsycINFO, Web of Science, SportDiscus, and Cochrane was performed for studies published between January 2000 and May 2018. Keywords and Medical Subject Headings terms related to PA, reproductive health, and weight gain were used. Studies were selected if they were intervention studies, if PA was delivered as part of an intervention to pre-menopausal women, and if any reproductive health outcome was reported. Quality analysis was performed using the Tool for the assEssment of Study qualiTy and reporting in EXercise.

OUTCOMES

Eighteen studies, with a mix of four types of study design (4 randomized controlled trials (RCTs), 11 randomized comparison trials, 2 non-randomized comparison trials, and 1 single-arm clinical trial), were identified. Comparisons included fertility treatment (four studies) and common treatments for women with polycystic ovary syndrome (PCOS) symptoms (nine studies). Pooled analysis of data from three of the four studies with a control group showed higher pregnancy [risk ratio (RR) 2.10, 95% CI (1.32, 3.35); three studies] and live birth [RR 2.11, 95% CI (1.02, 4.39); two studies] rates in the intervention groups compared with non-therapy controls. Aggregated data from the fertility treatment comparative studies (i.e. those that compared PA with standard fertility treatment such as clomiphene, gonadotrophins, and/or IVF) showed no significant intervention differences: RR 1.46, 95% CI (0.87, 2.45) for clinical pregnancy (four studies) and RR 1.09, 95% CI (0.56, 2.12) for live births (two studies). Pooled analysis from the comparison trials that used pharmaceutical or dietary treatment for PCOS as comparison showed higher pregnancy rates [RR 1.59, 95% CI (1.06, 2.38); five studies] and live birth rates [RR 2.45, 95% CI (1.24, 4.83); two observations] in the PA intervention groups than in the comparison groups. Analysis of other outcomes, such as ovulation rates, menstrual regularity, and conception rates, showed no differences between the PA intervention and comparison groups.

WIDER IMPLICATIONS

There is emerging evidence from RCT that PA may improve pregnancy rates in women with reproductive health problems. Comparative studies indicate that PA intervention may be as effective as other commonly used clinical intervention strategies for improving reproductive health outcomes. While the type, intensity, frequency, and duration of optimal PA intervention, and the role of PA independent of weight loss, remain unclear, these preliminary findings suggest that PA may be an affordable and feasible alternative or complementary therapy to fertility treatments.

Metabolic dysfunction in polycystic ovary syndrome: Pathogenic role of androgen excess and potential therapeutic strategies

Background

Polycystic ovary syndrome (PCOS) is the most common endocrinopathy among reproductive age women. Although its cardinal manifestations include hyperandrogenism, oligo/anovulation, and/or polycystic ovarian morphology, PCOS women often display also notable metabolic comorbidities. An array of pathogenic mechanisms have been implicated in the etiology of this heterogeneous endocrine disorder; hyperandrogenism at various developmental periods is proposed as a major driver of the metabolic and reproductive perturbations associated with PCOS. However, the current understanding of the pathophysiology of PCOS-associated metabolic disease is incomplete, and therapeutic strategies used to manage this syndrome's metabolic complications remain limited.

Scope of review

This study is a systematic review of the potential etiopathogenic mechanisms of metabolic dysfunction frequently associated with PCOS, with special emphasis on the metabolic impact of androgen excess on different metabolic tissues and the brain. We also briefly summarize the therapeutic approaches currently available to manage metabolic perturbations linked to PCOS, highlighting current weaknesses and future directions.

Major conclusions

Androgen excess plays a prominent role in the development of metabolic disturbances associated with PCOS, with a discernible impact on key peripheral metabolic tissues, including the adipose, liver, pancreas, and muscle, and very prominently the brain, contributing to the constellation of metabolic complications of PCOS, from obesity to insulin resistance. However, the current understanding of the pathogenic roles of hyperandrogenism in metabolic dysfunction of PCOS and the underlying mechanisms remain largely incomplete. In addition, the development of more efficient, even personalized therapeutic strategies for the metabolic management of PCOS patients persists as an unmet need that will certainly benefit from a better comprehension of the molecular basis of this heterogeneous syndrome.

Peroxisome proliferator-activated receptor gamma blunts endothelin-1-mediated contraction of the uterine artery in a murine model of high-altitude pregnancy

The environmental hypoxia of high altitude (HA) increases the incidence of intrauterine growth restriction (IUGR) approximately threefold. The peroxisome proliferator-activated receptor γ (PPAR-γ), a ligand-activated nuclear receptor that promotes vasorelaxation by increasing nitric oxide and downregulating endothelin-1 (ET-1) production, has been implicated in IUGR. Based on our prior work indicating that pharmacologic activation of the PPARγ pathway protects against hypoxia-associated IUGR, we used an experimental murine model to determine whether such effects may be attributed to vasodilatory effects in the uteroplacental circulation. Using wire myography, ex vivo vasoreactivity studies were conducted in uterine arteries (UtA) isolated from pregnant mice exposed to hypoxia or normoxia from gestational day 14.5 to 18.5. Exposure to troglitazone, a high-affinity PPARγ agonist-induced vasorelaxation in UtA preconstricted with phenylephrine, with HA-UtA showing increased sensitivity. Troglitazone blunted ET-1-induced contraction of UtA in hypoxic and normoxic dams equivalently. Immunohistological analysis revealed enhanced staining for ET-1 receptors in the placental labyrinthine zone in hypoxic compared to normoxic dams. Our results suggest that pharmacologic PPAR-γ activation, via its vasoactive properties, may protect the fetal growth under hypoxic conditions by improving uteroplacental perfusion and thereby justify further investigation into PPARγ as a therapeutic target for IUGR in pregnancies complicated by hypoxia.

Lifestyle and Food Habits Impact on Chronic Diseases: Roles of PPARs

Peroxisome proliferator-activated receptors (PPARs) are nuclear receptors that exert important functions in mediating the pleiotropic effects of diverse exogenous factors such as physical exercise and food components. Particularly, PPARs act as transcription factors that control the expression of genes implicated in lipid and glucose metabolism, and cellular proliferation and differentiation. In this review, we aim to summarize the recent advancements reported on the effects of lifestyle and food habits on PPAR transcriptional activity in chronic disease.

Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction

The hypoxia of high-altitude (HA) residence increases the risk of intrauterine growth restriction (IUGR) and preeclampsia 3-fold, augmenting perinatal morbidity and mortality and the risk for childhood and adult disease. Currently, no effective therapies exist to prevent these vascular disorders of pregnancy. The peroxisome proliferator-activated receptor γ (PPAR-γ) is an important regulator of uteroplacental vascular development and function and has been implicated in the pathogenesis of IUGR and preeclampsia. Here, we used a model of HA pregnancy in mice to determine whether hypoxia-induced fetal growth restriction reduces placental PPAR-γ protein expression and placental vascularization and, if so, to evaluate the effectiveness of the selective PPAR-γ agonist pioglitazone (PIO) for preventing hypoxia-induced IUGR. Hypoxia resulted in asymmetric IUGR, placental insufficiency, and reduced placental PPAR-γ expression; PIO prevented approximately half of the fetal growth restriction and attenuated placental insufficiency. PIO did not affect fetal growth under normoxia. Although PIO was beneficial for fetal growth, PIO treatment reduced placental vascular density of the labrynthine zone in normoxic and hypoxic (Hx) conditions, and mean vascular area was reduced in the Hx group. Our results suggest that pharmacological PPAR-γ activation is a potential strategy for preventing IUGR in pregnancies complicated by hypoxia, although further studies are needed to identify its likely metabolic or vascular mechanisms.-Lane, S. L., Dodson, R. B., Doyle, A. S., Park, H., Rathi, H., Matarrazo, C. J., Moore, L. G., Lorca, R. A., Wolfson, G. H., Julian, C. G. Pharmacological activation of peroxisome proliferator-activated receptor γ (PPAR-γ) protects against hypoxia-associated fetal growth restriction.

Effect of Exercise on Ovulation: A Systematic Review

BACKGROUND

Infertility has been described as a devastating life crisis for couples, and has a particularly severe effect on women, in terms of anxiety and depression. Anovulation accounts for around 30% of female infertility, and while lifestyle factors such as physical activity are known to be important, the relationship between exercise and ovulation is multi-factorial and complex, and to date there are no clear recommendations concerning exercise regimes.

OBJECTIVES

The objective of this review was to systematically assess the effect of physical activity on ovulation and to discuss the possible mechanisms by which exercise acts to modulate ovulation in reproductive-age women. This was done with a view to improve existing guidelines for women wishing to conceive, as well as women suffering from anovulatory infertility.

SEARCH METHODS

The published literature was searched up to April 2016 using the search terms ovulation, anovulatory, fertility, sport, physical activity and exercise. Both observational and interventional studies were considered, as well as studies that combined exercise with diet. Case studies and articles that did not report anovulation/ovulation or ovarian morphology as outcomes were excluded. Studies involving administered drugs in addition to exercise were excluded.

RESULTS

In total, ten interventions and four observational cohort studies were deemed relevant. Cohort studies showed that there is an increased risk of anovulation in extremely heavy exercisers (>60 min/day), but vigorous exercise of 30-60 min/day was associated with reduced risk of anovulatory infertility. Ten interventions were identified, and of these three have studied the effect of vigorous exercise on ovulation in healthy, ovulating women, but only one showed a significant disruption of ovulation as a result. Seven studies have investigated the effect of exercise on overweight/obese women suffering from polycystic ovary syndrome (PCOS) or anovulatory infertility, showing that exercise, with or without diet, can lead to resumption of ovulation. The mechanism by which exercise affects ovulation is most probably via modulation of the hypothalamic-pituitary-gonadal (HPG) axis due to increased activity of the hypothalamic-pituitary-adrenal (HPA) axis. In heavy exercisers and/or underweight women, an energy drain, low leptin and fluctuating opioids caused by excess exercise have been implicated in HPA dysfunction. In overweight and obese women (with or without PCOS), exercise contributed to lower insulin and free androgen levels, leading to the restoration of HPA regulation of ovulation.

CONCLUSIONS

Several clear gaps have been identified in the existing literature. Short-term studies of over-training have not always produced the disturbance to ovulation identified in the observational studies, bringing up the question of the roles of longer term training and chronic energy deficit. We believe this merits further investigation in specific cohorts, such as professional athletes. Another gap is the complete absence of exercise-based interventions in anovulatory women with a normal body mass index (BMI). The possibly unjustified focus on weight loss rather than the exercise programme means there is also a lack of studies comparing types of physical activity, intensity and settings. We believe that these gaps are delaying an efficient and effective use of exercise as a therapeutic modality to treat anovulatory infertility.

Lower Levels of Serum Adiponectin and the T Allele of rs1501299 of the ADIPOQ Gene Are Protective against Polycystic Ovarian Syndrome in Jordan

Background

Polycystic ovary syndrome (PCOS) is a common reproductive disorder. Obesity, which is linked with lower adiponectin levels, increases a woman's risk of developing PCOS; however, the association between adiponectin and PCOS is controversial. Adiponectin levels could be affected by single nucleotide polymorphisms (SNPs) in the ADIPOQ gene. This study aimed to test the relationship between serum adiponectin and PCOS in Jordan and the association between the rs2241766, rs1501299, and rs266729 SNPs in the ADIPOQ gene and PCOS.

Methods

One hundred and fifty-four women with PCOS and 149 age- and body mass index-matched normally menstruating controls were recruited. Serum adiponectin levels were measured using enzyme-linked immunosorbent assay. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis.

Results

Serum adiponectin levels were significantly lower (P=0.0064) in PCOS women and rs1501299 (+276 G/T) genotype distributions were significantly different (P=0.01) between them and normally menstruating women. Multivariate analysis revealed that adiponectin levels remained significantly lower in PCOS women (P=0.001; odds ratio [OR], 0.9; 95% confidence interval [CI], 0.84-0.96). The GT genotype of rs1501299 increased the risk of PCOS (P<0.001; OR, 5.46; 95% CI, 2.42-12.33) and increased the risk of PCOS by three-fold (P<0.001; OR, 3.00; 95% CI, 1.36-6.60) relative to the TT genotype. The GG genotype increased the risk of PCOS as well (P<0.001; OR, 3:00; 95% CI, 1.36-6.60).

Conclusion

PCOS is associated with lower serum adiponectin levels independent of age and body mass index. The T allele of the rs1501299 (+276 G/T) SNP of the ADIPOQ gene protects against PCOS.

Insulin-Sensitizers, Polycystic Ovary Syndrome and Gynaecological Cancer Risk

Preclinical, early phase clinical trials and epidemiological evidence support the potential role of insulin-sensitizers in cancer prevention and treatment. Insulin-sensitizers improve the metabolic and hormonal profile in PCOS patients and may also act as anticancer agents, especially in cancers associated with hyperinsulinemia and oestrogen dependent cancers. Several lines of evidence support the protection against cancer exerted by dietary inositol, in particular inositol hexaphosphate. Metformin, thiazolidinediones, and myoinositol postreceptor signaling may exhibit direct inhibitory effects on cancer cell growth. AMPK, the main molecular target of metformin, is emerging as a target for cancer prevention and treatment. PCOS may be correlated to an increased risk for developing ovarian and endometrial cancer (up to threefold). Several studies have demonstrated an increase in mortality rate from ovarian cancer among overweight/obese PCOS women compared with normal weight women. Long-term use of metformin has been associated with lower rates of ovarian cancer. Considering the evidence supporting a higher risk of gynaecological cancer in PCOS women, we discuss the potential use of insulin-sensitizers as a potential tool for chemoprevention, hypothesizing a possible rationale through which insulin-sensitizers may inhibit tumourigenesis.

Targets to treat metabolic syndrome in polycystic ovary syndrome

INTRODUCTION

Metabolic syndrome is comprised of a combination of the following states: increased insulin resistance, dyslipidemia, cardiovascular disease, and increased abdominal obesity. Women with polycystic ovary syndrome (PCOS) have an increased risk of developing metabolic syndrome over the course of their lives. Metabolic syndrome increases risk of major cardiovascular events, morbidity, quality of life, and overall health care costs. Though metabolic syndrome in women with PCOS is an area of great concern, there is no effective individual medical therapeutic to adequately treat this issue.

AREAS COVERED

This article will review key aspects of metabolic syndrome in PCOS. We will discuss classic and novel therapeutics to address metabolic syndrome in women with PCOS. We will conclude with the importance of developing strategic interventions to increase the compliance to lifestyle and dietary modification, in addition to appreciation of the emerging pharmaceutical therapeutics available.

EXPERT OPINION

Innovation in lifestyle modification, including diet, exercise, with and without dedicated stress reduction techniques is the future in treatment of metabolic syndrome in PCOS. Application of novel interventions, such as group medical care, may improve future adherence to lifestyle modification recommendations, in addition to or in combination with pharmaceutical therapeutics.

Modulating Intrafollicular Hormonal Milieu in Controlled Ovarian Stimulation: Insights From PPAR Expression in Human Granulosa Cells

Controlled ovarian stimulation (COS) leading to ovulation of multiple follicles is a crucial aspect of biomedical infertility care. Nevertheless, biomarkers useful for COS management are still lacking. Peroxisome proliferator-activated receptors (PPARs) are nuclear hormone receptors relevant to steroid metabolism in granulosa cells (GCs). We investigated whether PPARs and their steroidogenic targets were differentially expressed in GCs differentiated under different recombinant or urinary gonadotropin preparations. GCs from women subjected to COS with r-hFSH, r-hFSH/r-hLH, or hMG-HP were processed to assess expression of PPARα, PPARβ/δ, PPARγ, and steroidogenic enzymes under PPAR modulation. As an evidence of their activation, all PPAR isotypes with their coactivators, the retinoic-X-receptors (RXRs), localized in the nucleus. When GCs from r-hFSH/r-hLH group were compared with r-hFSH, a significant reduction of PPARα protein was observed. By contrast, an increase of PPARβ/δ at both protein and mRNA levels along with that of PPARγ protein were detected. The steroidogenic enzymes 17βHSD IV, 3βHSD II, and HMG-CoA red were downregulated in the r-hFSH/r-hLH group in comparison to r-hFSH unlike CYP19A1 that remained unchanged. In GCs from urinary FSH-LH stimulation (hMG-HP), PPARα was more expressed in comparison with r-hFSH/r-hLH group. Likewise, 3βHSD II and 17βHSD IV were increased suggesting that hMG-HP partially mimicked r-hFSH/r-hLH effects. In summary, transcript analysis associated to protein investigation revealed differential effects of COS protocols on PPARs and their steroidogenic targets in relation to LH and gonadotropin source. These observations candidate PPARs as new biomarkers of follicle competence opening new hypotheses on COS effects on ovarian physiology. J. Cell. Physiol. 231: 908-914, 2016. © 2015 Wiley Periodicals, Inc.

Paracrine Regulation of Steroidogenesis in Theca Cells by Granulosa Cells Derived from Mouse Preantral Follicles

Interaction partners of follicular cells play a significant role in steroidogenesis, follicular formation, and development. Androgen secreted by theca cells (TCs) can initiate follicle development and ovulation and provide precursor materials for estrogen synthesis. Therefore, studies on ovarian microenvironment will not only lead to better understanding of the steroidogenesis but also have clinical significance for ovarian endocrine abnormalities such as hyperandrogenism in polycystic ovary syndrome (PCOS). This study applied the Transwell coculture model to investigate if the interaction between granulosa and theca cells may affect androgen production in theca cells. Concentrations of testosterone and androstenedione in the spent medium were measured by radioimmunoassay and enzyme linked immunosorbent assay, respectively. The results show that the coculture with granulosa cells (GCs) increases steroidogenesis in TCs. In addition, testosterone and androstenedione productions in response to LH stimulation were also increased in the coculture model. Significantly increased mRNA expressions of steroidogenic enzymes (Star, Cyp11a1, Cyp17a1, and Hsd3b2) were observed in the cocultured TCs. Thus, GCs were capable of promoting steroidogenesis and LH responsiveness in TCs. This study provided a basis for further exploration of ovarian endocrine mechanism and pathologies.

Regulator of G protein signaling 5 is a determinant of gestational hypertension and preeclampsia

Preeclampsia is a systemic vascular disorder of pregnancy and is associated with increased sensitivity to angiotensin II (AngII) and hypertension. The cause of preeclampsia remains unknown. We identified the role of regulator of G protein (heterotrimeric guanine nucleotide–binding protein) signaling 5 (RGS5) in blood pressure regulation during pregnancy and preeclampsia. RGS5 expression in human myometrial vessels is markedly suppressed in gestational hypertension and/or preeclampsia. In pregnant RGS5-deficient mice, reduced vascular RGS5 expression causes gestational hypertension by enhancing vascular sensitivity to AngII. Further challenge by increasing AngII results in preeclampsia-like symptoms, namely, more severe hypertension, proteinuria, placental pathology, and reduced birth weight. In pregnant heterozygote null mice, treatment with peroxisome proliferator–activated receptor (PPAR) agonists normalizes vascular function and blood pressure through effects on RGS5. These findings highlight a key role of RGS5 at the interface between AngII and PPAR signaling. Because preeclampsia is refractory to current standard therapies, our study opens an unrecognized and urgently needed opportunity for treatment of gestational hypertension and preeclampsia.

The Role of Metformin in Metabolic Disturbances during Pregnancy: Polycystic Ovary Syndrome and Gestational Diabetes Mellitus

Maintenance of gestation implicates complex function of multiple endocrine mechanisms, and disruptions of the global metabolic environment prompt profound consequences on fetomaternal well-being during pregnancy and postpartum. Polycystic Ovary Syndrome (PCOS) and gestational diabetes mellitus (GDM) are very frequent conditions which increase risk for pregnancy complications, including early pregnancy loss, pregnancy-induced hypertensive disorders, and preterm labor, among many others. Insulin resistance (IR) plays a pivotal role in the pathogenesis of both PCOS and GDM, representing an important therapeutic target, with metformin being the most widely prescribed insulin-sensitizing antidiabetic drug. Although traditional views neglect use of oral antidiabetic agents during pregnancy, increasing evidence of safety during gestation has led to metformin now being recognized as a valuable tool in prevention of IR-related pregnancy complications and management of GDM. Metformin has been demonstrated to reduce rates of early pregnancy loss and onset of GDM in women with PCOS, and it appears to offer better metabolic control than insulin and other oral antidiabetic drugs during pregnancy. This review aims to summarize key aspects of current evidence concerning molecular and epidemiological knowledge on metformin use during pregnancy in the setting of PCOS and GDM.

Cholesterol and male fertility: what about orphans and adopted?

The link between cholesterol homeostasis and male fertility has been clearly suggested in patients who suffer from hyperlipidemia and metabolic syndrome. This has been confirmed by the generation of several transgenic mouse models or in animals fed with high cholesterol diet. Next to the alteration of the endocrine signaling pathways through steroid receptors (androgen and estrogen receptors); "orphan" and "adopted" nuclear receptors, such as the Liver X Receptors (LXRs), the Proliferating Peroxisomal Activated Receptors (PPARs) or the Liver Receptor Homolog-1 (LRH-1), have been involved in this cross-talk. These transcription factors show distinct expression patterns in the male genital tract, explaining the large panel of phenotypes observed in transgenic male mice and highlighting the importance of lipid homesostasis and the complexity of the molecular pathways involved. Increasing our knowledge of the roles of these nuclear receptors in male germ cell differentiation could help in proposing new approaches to either treat infertile men or define new strategies for contraception.

The expression of sex steroid synthesis and inactivation enzymes in subcutaneous adipose tissue of PCOS patients

Modulation of sex steroid pre-receptor in adipose tissue is important for the development of metabolic diseases, but its roles in the pathogenesis of polycystic ovary syndrome (PCOS) has not been fully characterized. Herein we compared the expression of key sex steroid converting enzymes in the subcutaneous adipose tissue (SAT) between patients with PCOS and the matched controls. Most of the sex steroid converting enzymes were highly expressed in the SAT, except 17α-hydroxylase (CYP17A1). Compared with the controls, PCOS patients showed significantly higher levels of 3β-hydroxysteroid dehydrogenase1-2 (3β-HSD1-2), aldo-keto reductase 1C 1-3 (AKR1C1-3) and leptin, but lower level of P450 aromatase and 5α-reductase 1. Interestingly, leptin was positively correlated to AKR1C2 expression and negatively to 5α-reductase1 as well as peroxisome proliferator-activated receptor γ (PPARγ). In summary, the expression of enzymes synthesizing testosterone and enzymes inactivating DHT and progesterone was higher in SAT of PCOS patients compared to controls. Correlation analysis indicated that increased leptin expression may be negatively related to local DHT level. These data suggested that sex steroid converting enzymes expression was different in SAT of PCOS patients that might contribute to abnormal testosterone and leptin level of PCOS patients.

Metformin and pioglitazone in polycystic ovarian syndrome: a comparative study

OBJECTIVES

To evaluate the effect of metformin and pioglitazone on insulin resistance, ovulation and hyperandrogenism in women with PCOS.

METHODS

100 patients of age 18-30 years were included in this randomised double blind trial for treatment with either metformin or pioglitazone for a period of 6 months.

RESULTS

Administration of metformin and pioglitazone for 6 months revealed that 50 % of the patients achieved menstrual cyclicity. A decline in F-G grading for hirsutism within the both the groups was observed. The lipid profile also showed a decrease in total cholesterol, an increase in HDL-C, a decrease in VLDL-C levels but more so in the pioglitazone group. HOMA-IR declined more than 50-55 % with pioglitazone and 15 % with metformin. Thus, pioglitazone may be a better treatment option as far as protection from tendency to development of diabetes is conscerned. The rise in serum SHBG levels and decline in free androgen index and L/H ratio are more remarkable with pioglitazone (P < 0.05). Ovulation was restored in 44.2 and 56 % of patients on metformin and pioglitazone, respectively.

CONCLUSION

Pioglitazone may be a new alternative for use in women with PCOS, providing more metabolic and reproductive benefits and possibly protection from developing diabetes and cardiovascular problem.

Interventional studies for polycystic ovarian syndrome in children and adolescents

Polycystic ovarian syndrome (PCOS) is characterized by chronic anovulation, clinical and/or biochemical hyperandrogenism, which can be associated with altered insulin action. Symptoms usually begin around menarche, but onset after puberty may also occur as a result of environmental modifiers such as weight gain. The consequences of PCOS extend beyond the reproductive axis; there is a substantial risk for development of metabolic and cardiovascular abnormalities similar to the metabolic syndrome. Currently, the treatment is targeted to the patient's primary complaint such as hirsutism, restoration of regular menses or pregnancy. Pharmacological agents available for the treatment of hirsutism include androgen suppressors and peripheral androgen blockers. Recently, our understanding of the role of insulin resistance has led to the use of insulin-sensitizing medications as first-choice therapy. In conjunction with weight reduction and exercise, a pharmacologic reduction in insulin levels by either metformin or thiazolidinediones ameliorates both hyperinsulinemia and hyperandrogenism.

Direct rosiglitazone action on steroidogenesis and proinflammatory factor production in human granulosa-lutein cells

BACKGROUND

Ovarian granulosa cells are the predominant source of estradiol and progesterone biosynthesis in vivo. Rosiglitazone, a synthetic agonist of the peroxisome proliferator-activated receptor gamma (PPAR gamma), is applied as the treatment of insulin resistance including women with PCOS. The aim of the study was to investigate the direct effects of rosiglitazone on steroidogenesis and proinflammatory factor production in human granulosa-lutein cells (GLCs).

METHODS

Primary human GLCs were separated during in vitro fertilization and cultured in the presence of rosiglitazone, GW9662 (an antagonist of PPAR gamma) and hCG. The mRNA expression of key steroidogenic factors including 3beta- hydroxysteriod dehydrogenase (3beta-HSD), cytochrome P-450 scc (CYP11A1), cytochrome P-450 aromatase (CYP19A1), and steroidogenic acute regulatory protein (StAR) were detected by quantitative real-time PCR. Estradiol and progesterone levels in GLCs cultures were measured by chemiluminescence immunoassay, and the proinflammtory factors (TNFalpha and IL-6) in conditioned culture media were measured by ELISA.

RESULTS

PPAR gamma mRNA levels increased up to 3.24 fold by rosiglitazone at the concentration of 30 microM compared to control (P<0.05). hCG alone or hCG with rosiglitazone had no significant effects on PPAR gamma mRNA levels. The CYP19A1 mRNA level at exposure to rosiglitazone alone showed a drop, but was not significantly reduced comparing to control. The expression levels of enzymes 3beta-HSD and CYP11A1 in all treatments did not alter significantly. The StAR mRNA expression at exposure to rosiglitazone was significantly increased comparing to control (P<0.05). The media concentrations of E2 and progesterone by rosiglitazone treatment showed a declining trend comparing to control or cotreatment with hCG, which did not reach significance. Most importantly, treatment with rosiglitazone decreased TNFalpha secretion in a statistically significant manner compared with control (P<0.05). The concentration of IL-6 following rosiglitazone exposure did not significantly decrease comparing to control.

CONCLUSION

In cultured GLCs, rosiglitazone stimulated StAR expression, but did not significantly affect steroidogenic enzymes, as well as E2 and progesterone production. Moreover, rosiglitazone significantly decreased the production of TNFalpha in human GLCs, suggesting that PPAR gamma may play a role in the regulation of GLCs functions through inhibiting proinflammatory factors.

Initiation of the expression of peroxisome proliferator-activated receptor gamma (PPAR gamma) in the rat ovary and the role of FSH

PPARgamma is highly expressed in granulosa cells by 23 days post-partum (pp) and is down-regulated in response to the LH surge. We tested the hypothesis that high levels of FSH during the neonatal period trigger the expression of PPARgamma. To determine when PPARgamma expression is initiated, ovaries were collected from neonatal rats. Messenger RNA for PPARgamma was undetectable on day 1, low from days 5-14, and increased by day 19 pp (p < 0.05). PPARgamma was detected in select granulosa cells in primary/early secondary follicles. Messenger RNA for the FSH receptor was detected as early as day 1 and remained steady throughout day 19 pp. The FSH receptor was detected by immunoblot analysis in ovaries collected 1, 2, and 5-9 days pp. In a subsequent experiment, neonatal rats were treated with acyline (GnRH antagonist) which significantly reduced FSH (p < 0.05) but not levels of mRNA for PPARgamma. The role of FSH in the induction of PPARgamma expression was further assessed in ovarian tissue from FORKO mice. Both mRNA and protein for PPARgamma were identified in ovarian tissue from FORKO mice. In summary, the FSH/FSH receptor system is present in granulosa cells prior to the onset of expression of PPARgamma. Reducing FSH during the neonatal period, or the ability to respond to FSH, did not decrease expression of mRNA for PPARgamma. These data indicate that FSH is not a primary factor initiating the expression of PPARgamma and that other agents play a role in activating its expression in the ovary.

Effects of rosiglitazone on ovarian function and fertility in animals with reduced fertility following fetal and neonatal exposure to nicotine

We have previously shown that in utero nicotine exposure causes impaired fertility, follicle immaturity, and ovarian dysfunction in adult female rat offspring. These characteristics overtly resemble the clinical profile of polycystic ovarian syndrome (PCOS) and recent studies have shown that thiazolidinediones such as rosiglitazone improve fertility in women with PCOS but the mechanism is not well defined. Our goal was to examine whether rosiglitazone would (1) ameliorate the altered ovarian physiology that occurs following fetal and neonatal exposure to nicotine and (2) to examine whether this could be due to normalization of ovarian vascularization. At weaning, offspring of nicotine-exposed dams were given either vehicle (NV) or rosiglitazone (3 mg kg(-1) day(-1); NR). Offspring of saline-exposed dams received vehicle (SV). Tissues were collected when the female offspring reached 26 weeks of age. NV animals had reduced granulosa cell proliferation and increased ovarian cell apoptosis. Treatment with rosiglitazone increased proliferation, and decreased apoptosis, compared NV animals. NV animals had decreased ovarian vascularity relative to controls, whereas NR animals had an intermediate level of ovarian vessel density. Moreover, ovaries from NV animals had decreased levels of the pro-angiogenic growth factors vascular endothelial growth factor (VEGF) and endocrine gland-derived VEGF both of which were increased with rosiglitazone treatment. Rosiglitazone reversed some of the nicotine effects in the ovary and increased ovarian vascularization, follicle maturation and improved oocyte competence. Rosiglitazone may be an important treatment option for PCOS and the present study provides a potential mechanism by which rosiglitazone may have beneficial effects on fertility in these patients.

The effect of thiazolidinediones on BMD and osteoporosis

Thiazolidinediones, also known as glitazones, are insulin-sensitizing medications that account for approximately 21% of oral antihyperglycemic drugs used in the US. Although the main therapeutic effects occur in adipose tissue, muscles and the liver, studies suggest effects in bone as well. Currently, two thiazolidinediones are marketed in the US-rosiglitazone and pioglitazone-and several others are under investigation. This Review examines the evidence regarding the effects of thiazolidinediones on skeletal health. These drugs appear to trigger preferential differentiation of mesenchymal stem cells into adipocytes rather than osteoblasts, leading to decreased bone formation and increased adipogenesis. Although only a few small, randomized studies have examined the effects of thiazolidinediones on bone in humans, the available data suggest that these agents contribute to bone loss in postmenopausal women; the relationship is less clear in men. On the basis of this limited evidence, the absolute increase in fracture risk associated with thiazolidinediones seems to be small. Pending data from future randomized, controlled trials of the association between thiazolidinediones and low bone mass, prescribers should consider use of these drugs as a risk factor for the development of osteoporosis in postmenopausal women.

Hepatic dysfunction and insulin insensitivity in type 2 diabetes mellitus: a critical target for insulin-sensitizing agents

The liver plays an essential role in maintaining glucose homeostasis, which includes insulin-mediated processes such as hepatic glucose output (HGO) and uptake, as well as in clearance of insulin itself. In type 2 diabetes, the onset of hyperglycaemia [itself a potent inhibitor of hepatic glucose output (HGO)], alongside hyperinsulinaemia, indicates the presence of hepatic insulin insensitivity. Increased HGO is central to the onset of hyperglycaemia and highlights the need to target hepatic insulin insensitivity as a central component of glucose-lowering therapy. The mechanisms underlying the development of hepatic insulin insensitivity are not well understood, but may be influenced by factors such as fatty acid oversupply and altered adipocytokine release from dysfunctional adipose tissue and increased liver fat content. Furthermore, although the impact of insulin insensitivity as a marker of cardiovascular disease is well known, the specific role of hepatic insulin insensitivity is less clear. The pharmacological tools available to improve insulin sensitivity include the biguanides (metformin) and thiazolidinediones (rosiglitazone and pioglitazone). Data from a number of sources indicate that thiazolidinediones, in particular, can improve multiple aspects of hepatic dysfunction, including reducing HGO, insulin insensitivity and liver fat content, as well as improving other markers of liver function and the levels of mediators with potential involvement in hepatic function, including fatty acids and adipocytokines. The current review addresses this topic from the perspective of the role of the liver in maintaining glucose homeostasis, its key involvement in the pathogenesis of type 2 diabetes and the tools currently available to reduce hepatic insulin insensitivity.