Insulin-lowering medications in polycystic ovary syndrome

Chronic hyperinsulinemia promotes meta-inflammation and extracellular matrix deposition in adipose tissue: Implications of nitric oxide

Various imperative studies support the notion that hyperinsulinemia (HI) itself serves as the common link between adipose tissue inflammation (ATI) and metabolic syndrome. However, the contribution of HI mediated ATI and its metabolic consequences are yet to be explored. We induced chronic HI per se in mice by administration of exogenous insulin for 8 weeks through mini-osmotic pumps. For the reduction of circulating insulin in response to excess calorie intake, we have partially ablated β-cells by using streptozotocin (STZ) in the diet-induced obesity (DIO) and genetic mice models (db/db). Flow cytometry analysis was performed for the quantification of immune cells in stromal vascular fraction (SVF) isolated from epididymal white adipose tissue (eWAT). Our studies demonstrated that chronic HI augmented ATI in terms of elevated pro-inflammatory cells (M1 macrophages and NK-cells) and suppressed anti-inflammatory cells (M2 macrophages, eosinophils and regulatory T-cells). These results were correlated with altered obesity-associated metabolic phenotype. Partial reduction of circulating insulin level attenuated excess calorie-induced ATI and improved insulin sensitivity. Mechanistically, an imbalance in M1 and M2 macrophage proportions in eWAT promoted iNOS (inducible nitric oxide synthase): arginase-1 imbalance that resulted into extracellular matrix (ECM) deposition and insulin resistance (IR) development. However, iNOS^-/- mice were protected from HI-induced M1:M2 macrophage imbalance, ECM deposition and IR in adipose tissue. Overall, we conclude that chronic HI per se contributed in ATI and iNOS corroborated ECM deposition.

ROLE OF INSULIN SENSITIZERS ON CARDIOVASCULAR RISK FACTORS IN POLYCYSTIC OVARIAN SYNDROME: A META-ANALYSIS

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is associated with an increase in cardiovascular (CV) risk factors such as insulin resistance, with accompanying hyperinsulinemia and hyperlipidemia, which are predisposing factors for type 2 diabetes mellitus and CV disease. The aim of this meta-analysis is to examine the effect of insulin sensitizers on clinical and biochemical features of PCOS and risk factors for CV disease.

METHODS

A systematic literature review was conducted, and randomized controlled clinical trials were identified by a search of bibliographic databases: Medline database (from 1966 forward), EMBASE (January 1985 forward), and Cochrane Central Register of Controlled Trials. Reviews of reference lists further identified candidate trials. Data was independently abstracted in duplicate by 2 investigators using a standardized data-collection form. Articles without a comparison group and randomization allocation were excluded. Reviewers worked independently and in duplicate to determine the methodological quality of trials, then collected data on patient characteristics, interventions, and outcomes.

RESULTS

Of 455 studies, 44 trials were eligible. A random effects model was used. Significant unadjusted results favoring treatment with insulin sensitizers were obtained for body mass index (BMI) (effect size [ES] of 0.58), waist to hip ratio (WHR) (ES of 0.02), low-density-lipoprotein cholesterol (LDL-C) (ES of 0.11), fasting insulin (ES of 2.82), fasting glucose (ES of 0.10), free testosterone (ES of 1.88), and androstenedione level (ES of 0.76).

CONCLUSION

Treatment with insulin sensitizers in women with PCOS results in improvement in CV factors such as BMI, WHR, LDL-C, fasting insulin, glucose, free testosterone, and androstenedione.

Implantation failure: molecular mechanisms and clinical treatment

BACKGROUND

Implantation is a complex initial step in the establishment of a successful pregnancy. Although embryo quality is an important determinant of implantation, temporally coordinated differentiation of endometrial cells to attain uterine receptivity and a synchronized dialog between maternal and embryonic tissues are crucial. The exact mechanism of implantation failure is still poorly understood.

METHODS

This review summarizes the current knowledge about the proposed mechanisms of implantation failure in gynecological diseases, the evaluation of endometrial receptivity and the treatment methods to improve implantation.

RESULTS

The absence or suppression of molecules essential for endometrial receptivity results in decreased implantation rates in animal models and gynecological diseases, including endometriosis, hydrosalpinx, leiomyoma and polycystic ovarian syndrome. The mechanisms are diverse and include abnormal cytokine and hormonal signaling as well as epigenetic alterations.

CONCLUSIONS

Optimizing endometrial receptivity in fertility treatment will improve success rates. Evaluation of implantation markers may help to predict pregnancy outcome and detect occult implantation deficiency. Treating the underlying gynecological disease with medical or surgical interventions is the optimal current therapy. Manipulating the expression of key endometrial genes with gene or stem cell-based therapies may some day be used to further improve implantation rates.

Beneficial effects of K-ATP channel openers in diabetes: an update on mechanisms and clinical experiences

Stresses associated with the diabetic state participate in the demise of beta-cells and therapies that eliminate or reduce such stresses are much needed. K-ATP channel openers, of which diazoxide is the most studied, are potentially useful because experimental studies show that they can counteract chronic over-stimulation of beta-cells and protect against toxic conditions, including relative hypoxia. Several mechanisms may underlie the beneficial effects of diazoxide; these may include both indirect (counteracting over-stimulation) and direct mitochondrial effects. Side effects of diazoxide have limited its use in human trials. We have tested lower doses than previously of diazoxide and thereby largely eliminated side effects. In this setting, we demonstrate positive effects on beta-cell function in type 2 diabetic patients who were simultaneously treated with bedtime insulin. However, such effects were absent in insulin-naïve patients. In newly diagnosed type 1 diabetic patients, a 6-month intervention with diazoxide failed to result in better preservation of beta-cell function. K-ATP channel openers have a potential to improve beta-cell function in subgroups of type 2 diabetes patients. Analogues of diazoxide with more potency in relation to side effects would heighten the possibilities for K-ATP channel openers to be of therapeutic use in type 1 diabetes.

The effects of Diane-35 and metformin in treatment of polycystic ovary syndrome: an updated systematic review

OBJECTIVES

To systematically evaluate the efficacy and safety of Diane-35 for treating polycystic ovary syndrome (PCOS) and compare it with metformin, either in combination or alone.

STUDY DESIGN

A systematic review and meta-analysis were conducted. Randomized controlled studies applying Diane-35 and metformin for treating PCOS were included. The primary outcome was hirsutism. Authors of primary articles were contacted and methodological quality was evaluated. Subgroups were drawn based on treatment duration and sensitivity analysis was conducted; heterogeneity and bias are discussed.

RESULTS

Twelve studies were included. The effect on improving hirsutism was not different between Diane-35 and metformin. Compared with Diane-35, metformin appeared to protect patients against glucose metabolic abnormality with treatment of at least 6 months. Except for triglycerides, no difference in lipid profile existed between Diane-35 and metformin. The evidence that Diane-35 deteriorates lipid and glucose metabolism was insufficient. Diane-35 could result in hypertension and headache. Methodological quality was still the key problem for studies.

CONCLUSIONS

Diane-35 is superior to metformin in reducing androgens, but inferior to metformin in reducing insulin. Whether Diane-35 deteriorates lipid metabolism and insulin resistance is still unclear.

Effects of metformin and ethinyl estradiol-cyproterone acetate on clinical, endocrine and metabolic factors in women with polycystic ovary syndrome

BACKGROUND

Polycystic ovary syndrome (PCOS) is a major endocrine abnormality that affects women of reproductive age. Oral contraceptive pills are usually the first choice of treatment for PCOS when fertility is not desired. Metformin, an insulin-sensitizing drug, has been shown to improve such metabolic abnormality. Aim. To compare the effects of a contraceptive pill in combination with metformin on the clinical, endocrine and metabolic parameters in obese and non-obese patients with PCOS.

METHODS

Sixty PCOS patients (25 obese, 35 non-obese) were enrolled in this prospective clinical study. PCOS was defined according to the Rotterdam criteria. Patients were randomized to oral treatment with Diane35 (35 microg ethinyl estradiol plus 2 mg cyproterone acetate), metformin or a combination of Diane35/metformin for 3 months. Body mass index (BMI), waist-to-hip ratio (WHR), Ferriman-Gallwey (FG) score, leuteinizing hormone (LH), follicle-stimulating hormone (FSH), testosterone, fasting insulin and glucose/insulin ratio were measured at baseline and at the end of treatment.

RESULTS

Diane35 resulted in a higher reduction of FG score in both obese and non-obese PCOS patients compared with metformin. Menstrual regularity was restored in all PCOS patients treated with Diane35 compared with only 28% of those receiving metformin. Metformin significantly decreased BMI and WHR in obese patients (p < 0.05). Testosterone levels decreased in all three groups. LH levels and LH/FSH ratio decreased with Diane35 and Diane35/metformin in both obese and non-obese patients. Metformin significantly decreased fasting insulin concentrations (p < 0.05 and p < 0.01) and increased the insulin sensitivity (p < 0.05) in both obese and non-obese PCOS patients, while no significant changes were observed in the Diane35 group. In addition, insulin levels also decreased (p < 0.05) in the Diane35/metformin group.

CONCLUSIONS

Our data show that a combination of metformin and contraceptive pill may be more effective in suppressing the hyperandrogenemia of obese and non-obese PCOS patients than metformin alone and may reduce insulin levels more than contraceptive pill alone. Hence, combined treatment may become a more effective therapeutic option for PCOS.

Endometrium in PCOS: Implantation and predisposition to endocrine CA

Polycystic ovarian syndrome (PCOS) is a common endocrinopathy characterized by oligo/anovulatiaon and elevated circulating androgens or evidence of hyperandrogenism after all known potential causes have been excluded. In addition, insulin resistance and accompanying hyperinsulinemia commonly occur in women with PCOS. There is increasing evidence that the endocrinologic and metabolic abnormalities in PCOS may have complex effects on the endometrium, contributing to the infertility and endometrial disorders observed in women with this syndrome. Androgen receptors and steroid receptor co-activators are over-expressed in the endometrium of women with PCOS. Also, biomarkers of endometrial receptivity to embryonic implantation-such as alpha(v)beta3-integrin and glycodelin-are decreased, and epithelial expression of estrogen receptor alpha (ERalpha) abnormally persists in the window of implantation in endometrium in women with PCOS. In addition to being responsive to the steroid hormones estradiol, progesterone, and androgens, the endometrium is also a target for insulin, the receptor for which is cyclically regulated in normo-ovulatory women. In vitro, insulin inhibits the normal process of endometrial stromal differentiation (decidualization). In addition, insulin-like growth factors (IGFs) and their binding proteins are regulated in and act on endometrial cellular constituents, and hyperinsulinemia down-regulates hepatic IGFBP-1, resulting in elevated free IGF-I in the circulation. Thus, elevated estrogen (without the opposing effects of progesterone in the absence of ovulation), hyperinsulinemia, elevated free IGF-I and androgens, and obesity all likely contribute to endometrial dysfunction, infertility, increased miscarriage rate, endometrial hyperplasia, and endometrial cancer common in women with PCOS. The potential mechanisms underlying these disorders, specifically in women with PCOS, are complex and await additional transdisciplinary research for their complete elucidation.

Evidence for metabolic and reproductive phenotypes in mothers of women with polycystic ovary syndrome

Dyslipidemia is a feature of polycystic ovary syndrome (PCOS), but its pathogenesis remains controversial. We performed this study of mothers of women with PCOS to test the hypothesis that dyslipidemia is a heritable trait in families of women with PCOS and to investigate the impact of age on reproductive and metabolic phenotypes. Fasting blood was obtained in 215 non-Hispanic white mothers of women with PCOS and 62 control women. The prevalence of metabolic syndrome was compared with that in non-Hispanic white women of comparable age from the National Health and Nutrition Examination Survey III. Mothers had higher total (P < 0.001) and low-density lipoprotein (LDL) cholesterol levels (P = 0.007), whereas high-density lipoprotein and triglyceride levels did not differ compared with control women. The only predictors of LDL levels in mothers were their daughters' LDL levels (r2 = 0.11, P < 0.001) and their own unbound testosterone levels (r2 = 0.04, P = 0.03). The prevalence of metabolic syndrome was increased in obese (body mass index > or = 30 kg/m2) mothers compared with obese non-Hispanic white women from the National Health and Nutrition Examination Survey III (P = 0.04). Thirty-one percent of mothers reported a history of menstrual irregularity. These mothers had higher androgen levels, markers of insulin resistance, and LDL levels than mothers with regular menses. LDL levels are increased in mothers of women with PCOS, suggestive of a heritable trait. A history of menstrual irregularity identifies mothers with features of PCOS. Obese mothers have a very high prevalence of metabolic syndrome. These findings suggest that both the reproductive and metabolic abnormalities persist with age in PCOS.

Thiazolidinediones for the Therapeutic Management of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a diagnosis made between late adolescence and the menopause in 5-10% of women. PCOS is a heterogeneous disorder of unknown etiology characterized by hyperandrogenic chronic anovulation. This syndrome consists of a diverse constellation of signs and symptoms, such as hirsutism, acne, acanthosis nigricans, obesity, menstrual irregularities, anovulation, and/or infertility. Features of the metabolic syndrome, including obesity, insulin resistance, and dyslipidemia, are common in this patient population. Recent insights into the pathophysiology of PCOS have shown insulin resistance and hyperinsulinemia to play a substantial role. Insulin resistance is increasingly recognized as a chronic, low-level, inflammatory state. Recent studies show that serum levels of inflammatory mediators, such as tumor necrosis factor-alpha and interleukin-6, are increased in the insulin-resistant conditions of obesity and PCOS. The optimal modality for long-term treatment should have positive effects on androgen synthesis, sex hormone-binding globulin production, the lipid profile, insulin sensitivity, inflammatory mediators, and clinical symptoms including acne, hirsutism, and irregular menstrual cycles. Treatment with insulin-sensitizing agents is a relatively new therapeutic strategy in women with PCOS. Current research has shown that the use of diabetes mellitus management practices aimed at reducing insulin resistance and hyperinsulinemia (such as weight reduction and the administration of oral antidiabetic drugs) can not only reverse testosterone and luteinizing hormone abnormalities and restore menstrual cycles, but can also improve glucose, insulin, proinflammatory cytokine, and lipid profiles.Clinical treatment with troglitazone, a member of the thiazolidinedione family, for the management of PCOS complications such as insulin resistance, hyperandrogenism, and anovulation was found to have beneficial effects; however, it was taken off the market over concerns of hepatotoxicity. Although troglitazone is no longer available in the US, numerous clinical trials have established the role of thiazolidinediones in the treatment of women with PCOS. Clinical data emerging regarding the utility of two of the newer, safer thiazolidinediones, pioglitazone and rosiglitazone, for this patient population, consistently demonstrate effective improvements of endocrine and ovulatory performance in women with PCOS. The benefit and importance of lifestyle modification and weight reduction, when it can be achieved, is still an important component in the long-term treatment of PCOS. Pharmacologic reduction in insulin levels using thiazolidinediones appears to offer another therapeutic modality for PCOS, which may ameliorate the progress of both hyperinsulinemia and hyperandrogenism. However, additional studies of patients so treated are necessary before these agents can be considered first-line treatment for PCOS. Convincing data from randomized controlled trials with sufficient power to detect both the benefits and risks of long-term treatment with thiazolidinediones in women with PCOS remain to be obtained.

Insulin-sensitizing agents: use in pregnancy and as therapy in polycystic ovary syndrome

Treatment with insulin-sensitizing agents is a relatively recent therapeutic strategy in women with polycystic ovary syndrome (PCOS) and insulin resistance. The key areas addressed in this review include PCOS and the development of type 2 diabetes mellitus and gestational diabetes, as well as the use of insulin-sensitizing agents, particularly metformin, in the management of infertility in obese and non-obese PCOS women. Treatment with metformin in PCOS women undergoing IVF and the use of metformin during gestation will be discussed. The challenge for the health care professional should be the appropriate utilization of pharmacotherapies to improve insulin sensitivity and lower circulating insulin levels resulting in beneficial changes in PCOS phenotype. Further research into the potential role of other insulin-sensitizing agents, such as pioglitazone and rosiglitazone, in the treatment of infertile women with PCOS is needed.

Acne and diet

Forbidden foods? "The first law of dietetics seems to be: If it tastes good, it's bad for you" (Isaac Asimov, Russian-born biochemist and science fiction writer). This was essentially the Magna Carta for dermatologists of the 1950s: anything coveted by the teenage palate was suspect for morning after acne. Today, half a century later, although the slant has shifted away for this line of thinking in our dermatologic textbooks, several articles on the beliefs and perceptions of acne patients showed that nothing much has changed and that they expect us to give them detailed instructions of what "acne-related" foods they should avoid. In one such study(1), diet was the third most frequently implicated factor (after hormones and genetics) as the cause of the disease, with 32% of the respondents selecting diet as the main cause, and 44% thinking that foods aggravate acne. In another study that analyzed knowledge about causes of acne among English teenagers, 11% of the responders blamed greasy food as the main cause of the disease(2), whereas in another study found that 41% of final-year medical students of the University of Melbourne chose diet as an important factor of acne exacerbation on a final examination.(3)

Screening for insulin resistance in women with polycystic ovarian syndrome

INTRODUCTION

Insulin resistance is implicated in the pathogenesis of polycystic ovarian syndrome (PCOS). Insulin-sensitizing agents are increasingly used in the treatment of infertility and hirsutism in PCOS. However, not all women with PCOS are insulin-resistant.

OBJECTIVE

To assess the degree of insulin resistance within a clinic population of women referred for treatment of oligomenorrhoea or infertility.

DESIGN

We evaluated 25 consecutive PCOS outpatients referred for treatment of menstrual dysfunction/infertility and a matched control group. All underwent a standard oral glucose tolerance test (OGTT) with serial insulin measurements. Insulin sensitivity was calculated using homeostasis model assessment (HOMA).

RESULTS

Five of the 25 clinic patients had abnormal glucose handling (two had previously unknown type 2 diabetes and three had impaired glucose tolerance). Fasting and 2-h insulin levels were significantly higher in the PCOS women. Mean HOMA-S (insulin sensitivity) was even lower for PCOS women with normal GTT status (mean (95% confidence interval): 0.53 (0.34-0.72)) than for controls (0.94 (0.84-1.04)) (F = 4.2, p < 0.001). HOMA-B (pancreatic beta-cell function) was nearly tripled for normal GTT status PCOS women at 273 (205-342) versus 105 (70-139) for controls (F = 6.8, p < 0.001).

CONCLUSIONS

The results suggest a role for routine measurement of HOMA-S in identifying women with PCOS with insulin resistance with a view to targeting them with insulin-sensitizing agents.

Effects of metformin combined with cyproterone acetate on clinical features, endocrine and metabolism of non-obese women with polycystic ovarian syndrome

In order to explore the effects of metformin combined with cyproterone acetate (CPA) on the clinical features, endocrine and metabolism of the patients with polycystic ovarian syndrome (PCOS), 50 cases of non-obese PCOS were randomly subjected to CPA (CPA treatment group, n = 25) and CPA+ metformin (n = 25) treatment for 6 months. Before and after treatment the body mass index (BMI), waist : hip ratio (WHR), ovarian volume, serum gonadotrophin, androgen and sex hormone-binding globulin (SHBG) levels, and fasting lipid, glucose and insulin levels were measured. The results showed that all of the parameters in two groups were similar before treatment. After treatment for 6 months in the CPA+ metformin group, BMI and WHR were significantly decreased, while insulin sensitivity was significantly decreased as Compared with those before treatment. In CPA group, no significant changes were found before and after treatment. Combined use of CPA and metformin could result in the reduction of serum androstenedione and increases of serum SHBG levels as compared with the CPA treatment alone. It was concluded that combined use of CPA and metformin could improve the insulin sensitivity, and further suppress the hyperandrogenism in non-obese women with PCOS.

Increased insulin-like growth factor-I levels in women with polycystic ovary syndrome, and beneficial effects of metformin therapy

We aimed to investigate whether metformin would reverse the endocrinopathy of polycystic ovary syndrome (PCOS), allowing resumption of cyclic ovulation and regular menses, and whether metformin causes any change in the serum concentration of insulin-like growth factor-I (IGF-I) in patients with PCOS. Fifty-eight women with PCOS participated in the study and received metformin at a dose of 850 mg three times a day (total 2550 mg) for 16 weeks. Serum concentrations of luteinizing hormone, follicle stimulating hormone, estradiol, free testosterone, total testosterone, 17-hydroxyprogesterone, dehydroepiandrosterone sulfate, fasting insulin, IGF-I, sex hormone binding globulin and insulin-like growth factor binding protein-1 (IGFBP-1) were evaluated before and after metformin treatment. Patients were divided into two groups as responders and non-responders according to the achievement of regular menstrual periods. The mean IGF-I levels decreased significantly on metformin therapy. After 16 weeks of metformin treatment, 55.17% of PCOS patients achieved regular menses. Only the change in serum levels of progesterone and IGF-I on metformin were statistically significant between responders and non-responders; metformin-induced decremental change in IGF-I levels were greater in responders. In conclusion, we observed that elevated IGF-I levels may have a crucial role in many consequences of PCOS in addition to hyperinsulinemia. By decreasing insulin and IGF-I levels, metformin therapy offers additional beneficial effects in resumption of regular menses. Thus, in PCOS patients with elevated levels of IGF-I, metformin may be considered as an appropriate agent to be used for the regulation of menstrual cycles.

Polycystic ovary syndrome: a review for primary providers

PCOS is a metabolic syndrome that exists throughout the world with much clinical heterogeneity. PCOS is now appreciated as encompassing two interrelated metabolic phenomena--insulin resistance and hyperandrogenism. Patients present with oligo-amenorrhea and clinical hyperandrogenism, and the diagnosis is based on clinical grounds with few laboratory tests necessary. Because patients are at higher than normal risk for diabetes, glucose intolerance, and hyperlipidemia, and perhaps at higher risk for coronary heart disease, newly diagnosed patients with PCOS should be evaluated for glucose intolerance and hyperlipidemia. The cornerstone of therapy today includes weight management, and further therapeutic intervention is focused on reproductive and cardiovascular health and treatment of insulin resistance. Clinical case continued The 17-year-old mentioned in the beginning of this article probably does have PCOS. She fits the clinical criteria: oligo-ovulation and hyper-androgenism (the acne and hirsutism). In addition, she is obese, which is also associated with PCOS. Her TSH and prolactin were normal, and as her presentation was not suggestive of an adrenal tumor or congenital adrenal hyperplasia (she had mild hirsutism, and those diagnoses are associated with more severe hyperandrogenism), no further laboratory evaluation was deemed necessary. Once the diagnosis was made, she was screened for lipid abnormalities and for glucose intolerance. Her LDL was 150, HDL 35; oral glucose tolerance test (OGTT) was normal. A pregnancy test was negative, and she was started on OCPs. Devoting herself to exercise and dietary change, she lost 10 pounds in her first 3 months after diagnosis. Her hirsutism and acne have improved with the OCPs and weight loss, and her menses are regular. She has elected to defer oral insulin sensitizers until her weight loss has stabilized. Findings PCOS is common in reproductive-aged women. Diagnosis is clinical and is supported by lab findings; there is significant clinical heterogeneity. Insulin resistance is likely central to the pathophysiology along with androgen excess. Health implications include infertility, diabetes, endometrial cancer, hyperlipidemia, and possibly coronary heart disease. Treatment is evolving and includes weight loss, OCPs, and insulin sensitizers.

Assessment and management of anovulatory infertility in polycystic ovary syndrome

PCOS is the most common cause of anovulatory infertility. Anovulation in PCOS is exacerbated by weight gain and improved by calorie restriction in overweight subjects. Fertility can usually be restored by appropriate choice of induction of ovulation, but careful monitoring is required, even when using clomiphene alone.

Laparoscopic treatment of polycystic ovaries: is it time to relinquish the procedure?

OBJECTIVE

To evaluate the role of laparoscopic ovarian drilling and treatment with metformin in the management of the polycystic ovary syndrome (PCOS).

DESIGN

A literature search was conducted using the keywords laparoscopy, laparoscopic ovarian drilling, laparoscopic ovarian diathermy, PCOS, metformin, and ovulation. The MEDLINE and EMBASE databases and the Cochrane Database of Systematic Reviews were searched.

RESULTS

No randomized comparisons have been done between laparoscopic ovarian drilling and metformin therapy. However, the ovulation and pregnancy rates appear to be similar for both techniques. Both treatments decrease the incidence of ovarian hyperstimulation and the cancellation rate of IVF cycles. However, unlike laparoscopic ovarian drilling, metformin may decrease the incidence of type 2 diabetes and coronary heart disease.

CONCLUSION(S)

Given the similar magnitude of the results without the potential risks and complication of surgery, we propose that laparoscopic ovarian drilling should be used sparingly in favor of less invasive treatment with metformin.

Voltage-dependent K(+) channels in pancreatic beta cells: role, regulation and potential as therapeutic targets

Insulin secretion from pancreatic islet beta cells is acutely regulated by a complex interplay of metabolic and electrogenic events. The electrogenic mechanism regulating insulin secretion from beta cells is commonly referred to as the ATP-sensitive K(+) (K(ATP)) channel dependent pathway. Briefly, an increase in ATP and, perhaps more importantly, a decrease in ADP stimulated by glucose metabolism depolarises the beta cell by closing K(ATP) channels. Membrane depolarisation results in the opening of voltage-dependent Ca(2+) channels, and influx of Ca(2+) is the main trigger for insulin secretion. Repolarisation of pancreatic beta cell action potential is mediated by the activation of voltage-dependent K(+) (Kv) channels. Various Kv channel homologues have been detected in insulin secreting cells, and recent studies have shown a role for specific Kv channels as modulators of insulin secretion. Here we review the evidence supporting a role for Kv channels in the regulation of insulin secretion and discuss the potential and the limitations for beta-cell Kv channels as therapeutic targets. Furthermore, we review recent investigations of mechanisms regulating Kv channels in beta cells, which suggest that Kv channels are active participants in the regulation of beta-cell electrical activity and insulin secretion.

Metformin has direct effects on human ovarian steroidogenesis

OBJECTIVE

To investigate the possibility of direct effects of metformin on ovarian steroidogenesis.

DESIGN

Cultured ovarian cells.

SETTING

Academic research environment.

PATIENT(S)

Women undergoing bilateral salpingoophorectomy for benign gynecological disease.

MAIN OUTCOME MEASURE(S)

Estradiol and P were measured in granulosa cell (GC) conditioned medium and androstenedione (A) and P in theca conditioned medium.

RESULT(S)

The effect of addition of metformin alone to GCs was variable, but significant inhibition of both P and E2 was seen (range 0%-30%). Metformin dose-dependently inhibited gonadotrophin and insulin-stimulated P and E2 production (range 25%-50%). In theca, metformin inhibited A production (0%-40%) with no effect on P. In the presence of insulin, A was inhibited dose-dependently and P increased by a similar magnitude.

CONCLUSION(S)

These results demonstrate a direct effect of metformin on ovarian steroidogenesis. The inhibitory effects on androgen production in particular would be beneficial in polycystic ovary syndrome (PCOS).

Clinical, endocrine and metabolic effects of metformin added to ethinyl estradiol-cyproterone acetate in non-obese women with polycystic ovarian syndrome: a randomized controlled study

BACKGROUND

Oral contraceptive pills (OC) are usually the first choice of treatment for polycystic ovarian syndrome (PCOS), when fertility is not desired. However, they do not improve, or may even further induce impairment of insulin sensitivity, which is already impaired in women with PCOS. In this prospective, randomized study, we analysed the additional benefits of adding metformin to the OC treatment in non-obese women with PCOS.

METHODS

After a baseline work-up including body mass index (BMI), waist:hip ratio (WHR), Ferriman-Gallwey score, ovarian volume, serum gonadotrophin, androgen and sex hormone-binding globulin (SHBG) levels, and fasting lipid, glucose and insulin levels, 40 non-obese women with PCOS were assigned either to the OC or to the OC + metformin treatment by computer-assisted randomization. At the end of the 4 month follow-up period, subjects were re-evaluated.

RESULTS

The two groups were similar at baseline. After treatment, women in the OC + metformin group had significant decreases in BMI and WHR, and a significant increase in insulin sensitivity, in contrast to those in the OC group, who had insignificant changes in these parameters. Adding metformin also caused significant improvements in serum androstenedione and SHBG levels compared with the OC treatment alone.

CONCLUSIONS

Adding metformin to the OC treatment may improve the insulin sensitivity, and may further suppress the hyperandrogenaemia in non-obese women with PCOS.

Adult polycystic ovary syndrome begins in childhood

Polycystic ovary syndrome (PCOS) frequently presents during adolescence and is the commonest cause of menstrual irregularity and hirsutism. The characteristic endocrine abnormalities include hypersecretion of androgens and LH. Metabolic dysfunction is also a feature of many young women with PCOS. Hyperinsulinaemia and insulin resistance, which can be regarded as an exaggeration of the normal metabolic changes that occur during puberty, are further amplified by obesity. The aetiology of PCOS is uncertain but there is evidence for a primary abnormality of ovarian androgen production which is manifest at puberty but may have its origins in childhood or even during fetal development.

Weight Loss and Medication in Polycystic Ovary Syndrome Therapy

Polycystic ovary syndrome, which is a complex syndrome, affects approximately 6% of reproductive-age women. Many abnormalities are associated with polycystic ovary syndrome, but confusion still exists about their causation. Diagnosis of polycystic ovary syndrome is by exclusion. Management of the metabolic aspects of polycystic ovary syndrome focuses on minimizing insulin resistance and hyperinsulinemia with diet therapy or insulin-lowering drugs.