Troglitazone, an insulin-sensitizing thiazolidinedione, represses combined stimulation by LH and insulin of de novo androgen biosynthesis by thecal cells in vitro

Cannabinoids and PPAR Ligands: The Future in Treatment of Polycystic Ovary Syndrome Women with Obesity and Reduced Fertility

Cannabinoids (CBs) are used to treat chronic pain, chemotherapy-induced nausea and vomiting, and multiple sclerosis spasticity. Recently, the medicinal use of CBs has attracted increasing interest as a new therapeutic in many diseases. Data indicate a correlation between CBs and PPARs via diverse mechanisms. Both the endocannabinoid system (ECS) and peroxisome proliferator-activated receptors (PPARs) may play a significant role in PCOS and PCOS related disorders, especially in disturbances of glucose-lipid metabolism as well as in obesity and fertility. Taking into consideration the ubiquity of PCOS in the human population, it seems indispensable to search for new potential therapeutic targets for this condition. The aim of this review is to examine the relationship between metabolic disturbances and obesity in PCOS pathology. We discuss current and future therapeutic interventions for PCOS and related disorders, with emphasis on the metabolic pathways related to PCOS pathophysiology. The link between the ECS and PPARs is a promising new target for PCOS, and we examine this relationship in depth.

Resistance to the Insulin and Elevated Level of Androgen: A Major Cause of Polycystic Ovary Syndrome

PCOS has a wide range of negative impacts on women's health and is one of the most frequent reproductive systemic endocrine disorders. PCOS has complex characteristics and symptom heterogeneity due to the several pathways that are involved in the infection and the absence of a comm14on cause. A recent study has shown that the main etiology and endocrine aspects of PCOS are the increased level of androgen, which is also known as "hyperandrogenemia (HA)" and secondly the "insulin resistance (IR)". The major underlying cause of the polycystic ovary is these two IR and HA, by initiating the disease and its severity or duration. As a consequence, study on Pathogenesis is crucial to understand the effect of "HA" and "IR" on the pathophysiology of numerous symptoms linked to PCOS. A deep understanding of the pattern of the growth in PCOS for HA and IR can help ameliorate the condition, along with adjustments in nutrition and life, as well as the discovery of new medicinal products. However, further research is required to clarify the mutual role of IR and HA on PCOS development.

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.

Fetal programming by androgen excess in rats affects ovarian fuel sensors and steroidogenesis

Fetal programming by androgen excess is hypothesized as one of the main factors contributing to the development of polycystic ovary syndrome (PCOS). PCOS is more than a reproductive disorder, as women with PCOS also show metabolic and other endocrine alterations. Since both ovarian and reproductive functions depend on energy balance, the alterations in metabolism may be related to reproductive alterations. The present study aimed to evaluate the effect of androgen excess during prenatal life on ovarian fuel sensors and its consequences on steroidogenesis. To this end, pregnant rats were hyperandrogenized with testosterone and the following parameters were evaluated in their female offspring: follicular development, PPARG levels, adipokines (including leptin, adiponectin, and chemerin as ovarian fuel sensors), serum gonadotropins (LH and FSH), the mRNA of their ovarian receptors, and the expression of steroidogenic mediators. At 60 days of age, the prenatally hyperandrogenized (PH) female offspring displayed both an irregular ovulatory phenotype and an anovulatory phenotype with altered follicular development and the presence of cysts. Both PH groups showed altered levels of both proteins and mRNA of PPARG and a different expression pattern of the adipokines studied. Although serum gonadotropins were not impaired, there were alterations in the mRNA levels of their ovarian receptors. The steroidogenic mediators Star, Cyp11a1, Cyp17a1, and Cyp19a1 were altered differently in each of the PH groups. We concluded that androgen excess during prenatal life leads to developmental programming effects that affect ovarian fuel sensors and steroidogenesis in a phenotype-specific way.

Role of Lipotoxicity and Contribution of the Renin-Angiotensin System in the Development of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is a common and significant condition associated with hyperandrogenism, infertility, low quality of life, and metabolic comorbidities. One possible explanation of PCOS development is cellular dysfunction induced by nonesterified fatty acids (NEFAs), that is, lipotoxicity, which could explain both the hyperandrogenemia and insulin resistance that characterize women with PCOS. The literature suggests that androgen biosynthesis may be induced by overexposure of androgen-secreting tissues to NEFA and/or defective NEFA metabolism, leading to lipotoxic effects. Indeed, lipotoxicity could trigger androgenic hyperresponsiveness to insulin, LH, and ACTH. In most PCOS women, lipotoxicity also causes insulin resistance, inducing compensatory hyperinsulinemia, and may thus further increase hyperandrogenemia. Many approaches aimed at insulin sensitization also reduce lipotoxicity and have been shown to treat PCOS hyperandrogenemia. Furthermore, our group and others found that angiotensin II type 2 receptor (AT2R) activation is able to improve lipotoxicity. We provided evidence, using C21/M24, that AT2R activation improves adipocytes' size and insulin sensitivity in an insulin-resistant rat model, as well as androgen levels in a PCOS obese rat model. Taken together, these findings point toward the important role of lipotoxicity in PCOS development and of the RAS system as a new target for the treatment of PCOS.

Peroxisome Proliferator-Activated Receptors in Female Reproduction and Fertility

Reproductive functions may be altered by the exposure to a multitude of endogenous and exogenous agents, drug or environmental pollutants, which are known to affect gene transcription through the peroxisome proliferator-activated receptors (PPARs) activation. PPARs act as ligand activated transcription factors and regulate metabolic processes such as lipid and glucose metabolism, energy homeostasis, inflammation, and cell proliferation and differentiation. All PPARs isotypes are expressed along the hypothalamic-pituitary-gonadal axis and are strictly involved in reproductive functions. Since female fertility and energy metabolism are tightly interconnected, the research on female infertility points towards the exploration of potential PPARs activating/antagonizing compounds, mainly belonging to the class of thiazolidinediones (TZDs) and fibrates, as useful agents for the maintenance of metabolic homeostasis in women with ovarian dysfunctions. In the present review, we discuss the recent evidence about PPARs expression in the hypothalamic-pituitary-gonadal axis and their involvement in female reproduction. Finally, the therapeutic potential of their manipulation through several drugs is also discussed.

Leuprolide acetate-stimulated androgen response during female puberty

BACKGROUND

A physiological increase in androgen levels occurs during adolescence. Measuring androgen concentrations is the best method to distinguish normal evolution processes from hyperandrogenic disorders.

HYPOTHESIS

The increase in circulating androgens during puberty is inversely associated with insulin sensitivity in normal weight girls.

OBJECTIVE

To assess circulating levels of ovarian androgens and anti-Müllerian hormone (AMH) at baseline and after GnRH analogue (GnRH-a) stimulation in normal pubertal girls across different Tanner stages. We also studied the association between this response and insulin sensitivity.

DESIGN

Prospective study of healthy girls (6-12 years) from the local community (n = 63).

METHODS

Tanner I (n = 23) subjects were assessed cross-sectionally, and Tanner II girls (n = 40) were evaluated every 6 months until they reached Tanner V. Early morning dehydroepiandrosterone sulphate (DHEA-S), AMH, sex hormone-binding globulin (SHBG), androstenedione, glucose and insulin levels were measured. A GnRH-a test (500 μg/m(2) ; sc) and oral glucose intolerance test (OGTT) were performed. Differences throughout puberty were evaluated.

RESULTS

Basal and/or stimulated Testosterone DHEA-S and 17-hydroxyprogesterone (17OHP) were inversely associated with insulin sensitivity (WIBSI) from the beginning of puberty, whereas androstenedione was directly associated with gonadotrophins. AMH was inversely associated with basal and stimulated gonadotrophins and directly with insulin area under the curve (AUC) only in the early stages of puberty. 17OHP and testosterone responsiveness increased significantly during puberty in all subjects, whereas testosterone levels changed less consistently. This pattern of ovarian-steroidogenic response was most evident during mid- and late puberty. Moreover, during late puberty only, basal 17OHP, testosterone and DHEA-S were positively associated with gonadotrophins.

CONCLUSION

In normal nonobese girls born appropriate for gestational age, androgen synthesis was associated with insulin sensitivity in early puberty and with LH only in late puberty.

Rosiglitazone stimulates peroxisome proliferator-activated receptor gamma expression and directly affects in vitro steroidogenesis in porcine ovarian follicles

Rosiglitazone is a peroxisome proliferator-activated receptor gamma (PPARγ) synthetic activator from the group of thiazolidinediones often used in the treatment of chronic diseases such as type 2 diabetes and other forms of insulin resistance. The present in vitro study assessed the direct effects of rosiglitazone at 25 and 50 μM doses on PPARγ gene expression, steroid secretion (progesterone [P4], androstenedione [A4], testosterone [T], and estradiol), and protein expression of PPARγ, 3βHSD, CYP17, 17βHSD, CYP19 by porcine ovarian follicles from prepubertal and cycling animals. We analyzed also steroid enzymatic activity by conversion of pregnen-3β-ol-20-one to P4, P4 to A4, and A4 to T. Our results indicated that rosiglitazone increased significantly PPARγ expression, P4 secretion, 3βHSD activity, and protein expression. Rosiglitazone decreased A4 and T secretion by reducing the expression and activity of CYP17 and 17βHSD and did not change estradiol secretion and CYP19. Similarly results was observed both in prepubertal and cycling pigs. Our results indicate that these direct effects of rosiglitazone on ovarian steroidogenesis provide a framework for testing several potential new mechanisms of PPAR-γ actions on porcine ovarian function.

Altered multihormone synchrony in obese patients with polycystic ovary syndrome

Luteinizing hormone (LH) concentrations and pulsatility are increased in obese women with polycystic ovary syndrome (PCOS). In addition, patients have hyperandrogenemia and insulin resistance. The mechanisms involved in aberrant hormone regulation in PCOS are still unclear. We investigated 15 obese PCOS women with a body mass index between 30 and 54 kg/m(2) and 9 healthy obese controls (body mass index, 31-60 kg/m(2)) with regular menstrual cycles. Subjects underwent 24-hour blood sampling at 10-minute intervals for later measurements of LH, leptin, testosterone, and insulin concentrations. Data were analyzed with a new deconvolution program, approximate entropy (and bivariate approximate entropy), and a cross-correlation network. Patients had increased LH pulse frequency and more than 2-fold greater daily LH secretion, with diminished pattern regularity. Testosterone secretion was increased 2-fold, but pattern regularity was similar to that in controls. In the network construct, insulin was correlated positively with LH, whereas leptin and testosterone were correlated negatively with LH. Bivariate synchrony of LH with insulin was decreased. Short-term caloric restriction paradoxically increased LH secretion by 1.5-fold and pattern irregularity, and reduced interpulse variability. Testosterone secretion and fasting concentrations of estradiol and sex hormone-binding globulin levels remained unchanged. Correlations between LH and insulin, leptin, and calculated free testosterone decreased. This study demonstrates marked alterations in the control of LH secretion in PCOS in the fed and calorie-restricted states. The ensemble results point to abnormal feedback control of not only the GnRH-gonadotrope complex, but also LH's relationships with leptin, insulin, and testosterone.

PPAR Gamma: Coordinating Metabolic and Immune Contributions to Female Fertility

Peroxisome proliferator-activated receptor gamma (PPARG) regulates cellular functions such as adipogenesis and immune cell activation. However, new information has indicated additional roles of PPARG directing the cyclic changes that occur within ovarian tissue of female mammals, including those that facilitate the release of oocytes each estrous cycle. In addition to ovarian PPARG expression and function, many PPARG actions within adipocytes and macrophages have additional direct and indirect implications for ovarian function and female fertility. This encompasses the regulation of lipid uptake and transport, insulin sensitivity, glucose metabolism, and the regulation of inflammatory mediator synthesis and release. This review discusses the developing links between PPARG activity and female reproductive function, and highlights several mechanisms that may facilitate such a relationship.

Thiazolidinediones and Fertility in Polycystic Ovary Syndrome (PCOS)

Polycystic ovary syndrome (PCOS) is the most frequent cause of female infertility. The treatment of PCOS patients with insulin sensitizers, such as metformin or thiazolidinediones, increases the ovulation rate and the number of successful pregnancies. The positive action of the insulin-sensitizing treatments could be explained by a decrease in the peripheral insulin resistance but also by a direct action at the ovarian level. We report in this review different hypotheses of thiazolidinediones actions to improve PCOS (steroid secretion by ovarian cells ; insulin sensitivity in muscle and adipocyte and fat redistribution).

Insulin and hyperandrogenism in women with polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a very common endocrine disorder characterized by chronic anovulation, clinical and/or biochemical hyperandrogenism, and/or polycystic ovaries. But most experts consider that hyperandrogenism is the main characteristic of PCOS. Several theories propose different mechanisms to explain PCOS manifestations: (1) a primary enzymatic default in the ovarian and/or adrenal steroidogenesis; (2) an impairment in gonadotropin releasing hormone (GnRH) secretion that promotes luteal hormone (LH) secretion; or (3) alterations in insulin actions that lead to insulin resistance with compensatory hyperinsulinemia. However, in the past 20 years there has been growing evidence supporting that defects in insulin actions or in the insulin signalling pathways are central in the pathogenesis of the syndrome. Indeed, most women with PCOS are metabolically insulin resistant, in part due to genetic predisposition and in part secondary to obesity. But some women with typical PCOS do not display insulin resistance, which supports the hypothesis of a genetic predisposition specific to PCOS that would be revealed by the development of insulin resistance and compensatory hyperinsulinemia in most, but not all, women with PCOS. However, these hypotheses are not yet appropriately confirmed, and more research is still needed to unravel the true pathogenesis underlying this syndrome. The present review thus aims at discussing new concepts and findings regarding insulin actions in PCOS women and how it is related to hyperandrogenemia.

Impact of differential P450c17 phosphorylation by cAMP stimulation and by starvation conditions on enzyme activities and androgen production in NCI-H295R cells

CYP17A1 plays a pivotal role in the biosynthesis of androgens in the adrenals and the gonads. Although this enzyme catalyzes two different reactions on one single active site, its specific activities are regulated independently. Although the 17alpha-hydroxylase activity is rather constant and regulated by gene expression, the 17,20-lyase activity varies significantly with the amount of cofactors or by protein phosphorylation. cAMP increases CYP17A1 expression, P450c17 phosphorylation, and androgen production. However, the exact mechanism(s) and the specific regulators of CYP17A1 remain unknown. Therefore, we studied the regulation of adrenal androgen biosynthesis in human adrenal H295R cells focusing on CYP17A1. We analyzed androgen production and P450c17 activities in H295R cells grown under normal and serum-free conditions and/or after stimulation with 8-bromoadenosine-cAMP. H295R cells grown in starvation medium produced more androgens and had decreased HSD3B2 expression and activity but increased P450c17-17,20-lyase activity and serine phosphorylation. Although starvation increased serine phosphorylation of P450c17 specifically, cAMP stimulation enhanced threonine phosphorylation exclusively. Time-course experiments revealed that a short cAMP stimulation augmented threonine phosphorylation of P450c17 but did not increase 17,20-lyase activity. By contrast, long cAMP stimulation increased androgen production through increased P450c17 activities by enhancing CYP17A1 gene expression. We conclude that serum withdrawal shifts steroidogenesis of H295R cells towards androgen production, providing a suitable model for detailed studies of androgen regulation. In addition, our study shows that starvation and cAMP stimulation regulate P450c17 phosphorylation differentially and that an increase in P450c17 phosphorylation does not necessarily lead to enhanced enzyme activity and androgen production.

The role of genetic variation in peroxisome proliferator-activated receptors in the polycystic ovary syndrome (PCOS): an original case-control study followed by systematic review and meta-analysis of existing evidence

OBJECTIVE

To study the association of polymorphisms in the genes encoding peroxisome proliferator-activated receptors (PPARs) with the polycystic ovary syndrome (PCOS).

DESIGN

Case-control study and meta-analysis of published evidence.

PATIENTS

One hundred and sixty-one polycystic ovary syndrome patients and 113 non-hyperandrogenic women.

MEASUREMENTS

Genotyping for PPAR-gamma coactivator-1 gene (PPARGC1A) Gly482Ser, PPAR-alpha Leu162Val, PPAR-delta rs2267668A/G, PPAR-delta-87T/C, PPAR-gamma2 Pro12Ala and PPAR-gamma2 -681C/G variants and systematic review of the literature using the Entrez-PubMed search engine, followed by meta-analysis whenever possible.

RESULTS

Polycystic ovary syndrome patients carried the Gly482Ser variant in PPARGC1A more frequently than controls (72%vs. 58%, chi(2 )=( )5.54 P = 0.019), whereas carriers of the PPAR-alpha Leu162Val, PPAR-delta rs2267668A/G, PPAR-delta-87T/C, PPAR-gamma2 Pro12Ala and PPAR-gamma2 -681C/G variants were distributed similarly among both groups. The interaction between the PPARGC1A Gly482Ser and PPAR-delta-87T/C variants was also associated with PCOS (OR = 1.24, 95% CI 1.05-1.50, P = 0.008). The systematic review identified 31 studies addressing associations between PPARs variants and PCOS; meta-analysis was possible for nine studies focusing on the PPAR-gamma2 Pro12Ala variant. Although the individual studies did not reveal any statistically significant association, meta-analysis uncovered that carrying the PPAR-gamma2 Pro12Ala variant was associated with a reduced probability of having PCOS (OR = 0.77, 95% CI 0.61-0.96, P = 0.025), and that this association may be mediated by an effect on insulin sensitivity.

CONCLUSIONS

Common polymorphisms in the PPARGC1A, PPAR-delta and PPAR-gamma2 loci are associated with PCOS.

Effect of chronic treatment with Rosiglitazone on Leydig cell steroidogenesis in rats: in vivo and ex vivo studies

BACKGROUND

The present study was designed to examine the effect of chronic treatment with rosiglitazone - thiazolidinedione used in the treatment of type 2 diabetes mellitus for its insulin sensitizing effects - on the Leydig cell steroidogenic capacity and expression of the steroidogenic acute regulatory protein (StAR) and cholesterol side-chain cleavage enzyme (P450scc) in normal adult rats.

METHODS

Twelve adult male Wistar rats were treated with rosiglitazone (5 mg/kg) administered by gavage for 15 days. Twelve control animals were treated with the vehicle. The ability of rosiglitazone to directly affect the production of testosterone by Leydig cells ex vivo was evaluated using isolated Leydig cells from rosiglitazone-treated rats. Testosterone production was induced either by activators of the cAMP/PKA pathway (hCG and dbcAMP) or substrates of steroidogenesis [22(R)-hydroxy-cholesterol (22(R)-OH-C), which is a substrate for the P450scc enzyme, and pregnenolone, which is the product of the P450scc-catalyzed step]. Testosterone in plasma and in incubation medium was measured by radioimmunoassay. The StAR and P450scc expression was detected by immunocytochemistry.

RESULTS

The levels of total circulating testosterone were not altered by rosiglitazone treatment. A decrease in basal or induced testosterone production occurred in the Leydig cells of rosiglitazone-treated rats. The ultrastructural and immunocytochemical analysis of Leydig cells from rosiglitazone-treated rats revealed cells with characteristics of increased activity as well as increased StAR and P450scc expression, which are key proteins in androgen biosynthesis. However, a number of rosiglitazone-treated cells exhibited significant mitochondrial damage.

CONCLUSION

The results revealed that the Leydig cells from rosiglitazone-treated rats showed significant reduction in testosterone production under basal, hCG/dbcAMP- or 22 (R)-OH-C/pregnenolone-induced conditions, although increased labeling of StAR and P450scc was detected in these cells by immunocytochemistry. The ultrastructural study suggested that the lower levels of testosterone produced by these cells could be due to mitochondrial damage induced by rosiglitazone.

Activation of PPARγ by Rosiglitazone does not negatively impact male sex steroid hormones in diabetic rats

Peroxisome proliferator-activated receptor gamma (PPARγ) activation decreased serum testosterone (T) in women with hyperthecosis and/or polycystic ovary syndrome and reduced the conversion of androgens to estradiol (E2) in female rats. This implies modulation of female sex steroid hormones by PPARγ. It is not clear if PPARγ modulates sex steroid hormones in diabetic males. Because PPARγ activation by thiazolidinedione increased insulin sensitivity in type 2 diabetes, understanding the long term impact of PPARγ activation on steroid sex hormones in males is critical. Our objective was to determine the effect of PPARγ activation on serum and intratesticular T, luteinizing hormone (LH), follicle stimulating hormone (FSH) and E2 concentrations in male Zucker diabetic fatty (ZDF) rats treated with the PPARγ agonist rosiglitazone (a thiazolidinedione). Treatment for eight weeks increased PPARγ mRNA and protein in the testis and elevated serum adiponectin, an adipokine marker for PPARγ activation. PPARγ activation did not alter serum or intratesticular T concentrations. In contrast, serum T level but not intratesticular T was reduced by diabetes. Neither diabetes nor PPARγ activation altered serum E2 or gonadotropins FSH and LH concentrations. The results suggest that activation of PPARγ by rosiglitazone has no negative impact on sex hormones in male ZDF rats.

Focus on the intermediate state: immature mRNA of cytochromes P450--methods and insights

The scattered and limited data on hnRNAs (pre-mRNAs) of cytochromes P450 (CYP) are compiled and discussed for the first time. The methods for determination and quantification of hnRNAs are compared. In most cases, CYP hnRNA levels were determined as a parameter of transcriptional activity. It is known, however, that some CYPs, in particular CYP2E1, are in addition specifically and extensively regulated by post-transcriptional processes. Obviously, these processes also influence the processing of CYP hnRNAs so that their levels cannot be considered a mere result of transcription. The underlying mechanisms of post-transcriptional CYP hnRNA and mRNA regulation are not well understood. It is our aim therefore to bring together available data on CYP hnRNA and to discuss them in the light of recent advances in knowledge concerning pre-mRNA processing and interactions between RNA and low molecular weight interfering RNAs. By doing this, we hope to drive research in a direction which appears promising in providing some long-awaited answers with respect to mechanisms of post-transcriptional CYP regulation.

Pioglitazone administration alters ovarian gene expression in aging obese lethal yellow mice

BACKGROUND

Women with polycystic ovary syndrome (PCOS) are often treated with insulin-sensitizing agents, e.g. thiazolidinediones (TZD), which have been shown to reduce androgen levels and improved ovulatory function. Acting via peroxisome proliferator-activated receptor (PPAR) gamma, TZD alter the expression of a large variety of genes. Lethal yellow (LY; C57BL/6J Ay/a) mice, possessing a mutation (Ay) in the agouti gene locus, exhibit progressive obesity, reproductive dysfunction, and altered metabolic regulation similar to women with PCOS. The current study was designed to test the hypothesis that prolonged treatment of aging LY mice with the TZD, pioglitazone, alters the ovarian expression of genes that may impact reproduction.

METHODS

Female LY mice received daily oral doses of either 0.01 mg pioglitazone (n = 4) or an equal volume of vehicle (DMSO; n = 4) for 8 weeks. At the end of treatment, ovaries were removed and DNA microarrays were used to analyze differential gene expression.

RESULTS

Twenty-seven genes showed at least a two-fold difference in ovarian expression with pioglitazone treatment. These included leptin, angiopoietin, angiopoietin-like 4, Foxa3, PGE1 receptor, resistin-like molecule-alpha (RELM), and actin-related protein 6 homolog (ARP6). For most altered genes, pioglitazone changed levels of expression to those seen in untreated C57BL/6J(a/a) non-mutant lean mice.

CONCLUSION

TZD administration may influence ovarian function via numerous diverse mechanisms that may or may not be directly related to insulin/IGF signaling.

Peroxisome proliferator-activated receptors: new players in the field of reproduction

Peroxisome proliferator-activated receptors (PPAR) are members of the nuclear hormone receptor superfamily. Synthetic ligands to one family member, PPARgamma, are currently widely used as treatment for chronic diseases such as diabetes type II and other insulin resistances, e.g. as seen in polycystic ovary syndrome (PCOS). Moreover, novel approaches employing knock-out mice demonstrated that PPARgamma seems to play a key role in placental and fetal development. This review describes recent insights into the role of PPARs in human reproduction with specific reference to infertility, placental maturation and fetal development as well as disturbed pregnancy. Further, we highlight the current knowledge on synthetic ligands to PPARgamma used as a treatment in women with PCOS.

17-hydroxyprogesterone responses to gonadotropin-releasing hormone disclose distinct phenotypes of functional ovarian hyperandrogenism and polycystic ovary syndrome

CONTEXT

The exaggerated 17-hydroxyprogesterone response to GnRH agonists, which reflects functional ovarian hyperandrogenism (FOH), is believed to be the prominent abnormality in women with polycystic ovary syndrome (PCOS).

OBJECTIVE

Our objectives were to quantify the prevalence of PCOS with FOH and to evaluate whether the presence of FOH may distinguish different clinical and biochemical phenotypes.

DESIGN, SETTING, AND PARTICIPANTS

We conducted an observational study at an academic hospital that included 148 PCOS women and 22 healthy age-matched normal-weight control women.

MAIN OUTCOME MEASURES

A hormone profile was taken at baseline and in response to (1-24)ACTH and to a GnRH agonist, buserelin, administered during dexamethasone suppression.

RESULTS

Based on the data obtained in the control subjects, the PCOS patients were divided into two groups, one with a normal (NR-PCOS, n = 78) and one with a high 17-hydroxyprogesterone response (HR-PCOS, n = 70) to buserelin. The two groups of PCOS subjects had similar anthropometric parameters and clinical signs of hyperandrogenism. Age and body weight at menarche were significantly lower and higher, respectively, in the HR-PCOS group than the NR-PCOS group. Moreover, the HR-PCOS group had higher basal testosterone (P < 0.001), free androgen index (P < 0.01), 17-hydroxyprogesterone (P < 0.05), estrogens (P < 0.05), area under the curve for insulin (insulin(AUC)) (P < 0.05), and C-peptide(AUC) (P < 0.01) and lower insulin sensitivity (as composite insulin sensitivity index) (P < 0.05) than the NR-PCOS group. The response of 17-hydroxyprogesterone to (1-24)ACTH (as percent variation) was lower in the HR-PCOS group with respect to the NR-PCOS group (P < 0.05), whereas the response of cortisol, androstenedione, and dehydroepiandrosterone was similar. Finally, the HR-PCOS group had lower percent suppression of androstenedione (P < 0.001) and 17-hydoxyprogesterone (P < 0.05) to dexamethasone. In a multiple regression model applied in all PCOS women, insulin(AUC) but not androgens or markers of insulin resistance predicted the 17-hydroxyprogesterone response to buserelin to a highly significant extent (t = 3.269; P < 0.01).

CONCLUSIONS

This study indicates that the paradigm that FOH is a specific feature of the PCOS status can no longer be sustained. We have shown that women with an exaggerated 17-hydroxyprogesterone response to a GnRH agonist, buserelin, are characterized by more severe hyperandrogenemia, glucose-stimulated beta-cell insulin secretion, and worse insulin resistance than those without evidence of FOH. Our data may be consistent with the hypothesis that excess insulin may represent a candidate factor responsible for FOH in these women, through the overactivation of the cytochrome P450 17alpha-hydroxylase/17,20-lyase (CYP17) enzyme pathway.

Suitability of recommended limits for fasting glucose tests in women with polycystic ovary syndrome

BACKGROUND

The Canadian and American Diabetes Associations recommend the use of an oral glucose tolerance test to screen for abnormal glucose tolerance among women with polycystic ovary syndrome when their fasting plasma glucose level is 5.7 mmol/L or more (Canadian guideline) and 5.6 mmol/L or more (American). Our objective was to determine the predictive value of 5.6 mmol/L as a fasting plasma glucose cutoff for detecting abnormal glucose tolerance in women with polycystic ovary syndrome, and then to define the optimal cutoff for this population.

METHODS

An oral glucose tolerance test was administered to 105 consecutive women with polycystic ovary syndrome referred to an academic reproductive endocrine clinic. We calculated sensitivity, specificity and likelihood ratios.

RESULTS

The sensitivity of a 5.6 mmol/L cutoff was 48% (95% confidence interval [CI] 30%-67%); its specificity, 98.7% (95% CI 96.1%-100%). With this cutoff, 52% of women with polycystic ovary syndrome whose glucose tolerance is abnormal would be missed. The prevalence of abnormal glucose tolerance was 28%, with a positive predictive value of 93% (95% CI 81%-100%) and a negative predictive value of 83% (95% CI 76%-91%). The likelihood ratio for a positive test was 36.7 (95% CI 5.0-267), and for a negative test, 0.5 (95% CI 0.4-0.7). The optimal fasting plasma glucose cutoff value was 5.0 mmol/L, with a 79% sensitivity (95% CI 65%-94%) and 66% specificity (95% CI 55%-77%). If this cutoff were used, 24% of women with abnormal glucose tolerance would still be missed.

INTERPRETATION

The Canadian and American recommendations--of screening for abnormal glucose tolerance with an oral glucose tolerance test only when the results of a fasting plasma glucose test are 5.7 mmol/L (or 5.6 mmol/L) or more--are inappropriate for women with polycystic ovary syndrome. We therefore recommend that all women with polycystic ovary syndrome have an oral glucose tolerance test.

Dermatologic manifestations of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) affects 5-10% of reproductive-aged women and is one of the most common endocrine disorders in women. The disorder is commonly characterized by elevated levels of androgen and insulin. Women with PCOS may present with a range of signs and symptoms, and face increased risks of reproductive, metabolic, cardiovascular, psychologic, and neoplastic sequelae, particularly if the condition is left unrecognized or untreated. The clinical definition of PCOS has changed in recent years and includes as one of its cardinal criteria the dermatologic manifestations of hyperandrogenism, chiefly hirsutism, acne vulgaris, and androgenetic alopecia. Acanthosis nigricans, a cutaneous sign of hyperinsulinemia, may also be present. These dermatologic features may provide early clinical clues to recognition of PCOS, and treatment of these cutaneous conditions may improve the patient's quality of life and psychologic well-being. The effects of androgen on pilosebaceous units in the skin can vary by anatomic location, producing pathophysiologic effects on hair growth and differentiation, sebaceous gland size and activity, and follicular keratinization. Treatment modalities may include hormonal therapy intended to modulate androgen production and action as well as non-hormonal therapies directed toward specific dermatologic conditions.

Somatotropic and gonadotropic axes linkages in infancy, childhood, and the puberty-adult transition

Integrative neuroendocrine control of the gonadotropic and somatotropic axes in childhood, puberty, and young adulthood proceeds via multiple convergent and divergent pathways in the human and experimental animal. Emerging ensemble concepts are required to embody independent, parallel, and interacting mechanisms that subserve physiological adaptations and pathological disruption of reproduction and growth. Significant advances in systems biology will be needed to address these challenges.

Metabolic and ovarian effects of rosiglitazone treatment for 12 weeks in insulin-resistant women with polycystic ovary syndrome

BACKGROUND

Insulin sensitizers have favourable metabolic and ovarian effects in polycystic ovary syndrome (PCOS). This study examined rosiglitazone, a thiazolidinedione, in PCOS.

METHODS

In a prospective, open-label study, the effects of rosiglitazone on metabolism and ovarian function were examined in 42 non-diabetic women with PCOS classified according to the National Institute of Child Health and Human Development criteria and insulin resistance (IR) by steady-state plasma glucose (SSPG) > or =10 mmol/l on octreotide-modified insulin suppression testing. Participants were randomized to rosiglitazone 2, 4 or 8 mg daily for 12 weeks. Endpoints included ovulation and menstrual pattern; serum testosterone, sex hormone-binding globulin (SHBG), and LH; and changes in IR and glucose-insulin responses on 8 h mixed-meal profile.

RESULTS

After rosiglitazone 8 mg daily for 12 weeks, SSPG declined and insulinaemia fell by 46%; lower doses gave lesser effects. Serum LH, total and free testosterone were unchanged; SHBG increased. With rosiglitazone, ovulation occurred in 23/42 women (55%), without significant dose dependence. Both before and during treatment, ovulators on rosiglitazone had lower circulating insulin and free testosterone and higher SHBG than non-ovulators. Testosterone declined only in a subgroup of ovulators with early vaginal bleeding after starting rosiglitazone.

CONCLUSIONS

Rosiglitazone in insulin-resistant PCOS promoted ovulation and dose-dependently decreased IR and insulinaemia; ovulators had lower circulating insulin and testosterone.

Peroxisome proliferator-activated receptors (PPARs) and ovarian function--implications for regulating steroidogenesis, differentiation, and tissue remodeling

The peroxisome proliferator-activated receptors (PPARs) are a family of transcription factors involved in varied and diverse processes such as steroidogenesis, angiogenesis, tissue remodeling, cell cycle, apoptosis, and lipid metabolism. These processes are critical for normal ovarian function, and all three PPAR family members--alpha, delta, and gamma, are expressed in the ovary. Most notably, the expression of PPARgamma is limited primarily to granulosa cells in developing follicles, and is regulated by luteinizing hormone (LH). Although much has been learned about the PPARs since their initial discovery, very little is known regarding their function in ovarian tissue. This review highlights what is known about the roles of PPARs in ovarian cells, and discusses potential mechanisms by which PPARs could influence ovarian function. Because PPARs are activated by drugs currently in clinical use (fibrates and thiazolidinediones), it is important to understand their role in the ovary, and how manipulation of their activity may impact ovarian physiology as well as ovarian pathology.

Effect of troglitazone on the excess testosterone and LH secretion in thyroidectomized, insulin-resistant, type 2 diabetic Goto-Kakizaki rats

Our previous study suggested that hypothyroidism in Goto-Kakizaki (GK) rats with insulin resistance and type 2 diabetes elevates their serum testosterone and luteinizing hormone (LH) levels and ovarian LH receptor messenger RNA (mRNA) expression. The present study assessed the effects of troglitazone (Tro), an insulin-sensitizing agent, on these hypothyroidism-induced hormonal changes in GK rats. GK and normal (Wistar strain) female rats were thyroidectomized (Tx) and then injected with 5 IU of equine chorionic gonadotropin (eCG) for 5 d starting 1 wk after thyroidectomy (the control groups). In the test groups, Tx GK and Wistar rats were injected with both eCG and Tro (100 mg kg-1) po for 5 d. Tro treatment had no effect on the elevated LH serum levels in eCG-treated Tx GK rats but suppressed their enhanced serum testosterone levels as well as significantly decreasing their LH receptor mRNA expression. Tro lowered testosterone and LH receptor mRNA levels in cultured theca cells. These results indicate that Tro lowers the elevated testosterone secretion and ovarian LH receptor mRNA expression that is induced in GK rats by Tx and gonadotropin treatment, which suggests that insulin resistance may be involved in enhancing testosterone production and LH receptor expression in the ovary.

Involvement of protein kinase C and cyclic adenosine 3',5'-monophosphate-dependent kinase in steroidogenic acute regulatory protein expression and steroid biosynthesis in Leydig cells

This study investigated the roles of the protein kinase C (PKC) and protein kinase A (PKA) pathways in regulating constitutive steroidogenesis and steroidogenic acute regulatory (STAR; herein designated by its common name, StAR) protein in R2C Leydig tumor cells. Inhibition of PKC and phospholipase C resulted in significant decreases in steroid production, phosphorylation of cAMP-responsive element binding (CREB) protein, and Star gene transcription under basal conditions in R2C cells. These observations were corroborated in MA-10 and mLTC-1 Leydig tumor cell lines, in which activation of PKC by phorbol-12-myristate-13-acetate (PMA, 10 nM) increased CREB phosphorylation and total StAR (tot-StAR) protein expression. However, induction of StAR protein by PMA did not result in the expected concomitant increase in steroids because PKC failed to phosphorylate StAR, the biologically active form of the protein. However, in conjunction with PMA, minor increases in PKA activity using submaximal doses of (Bu)2cAMP (0.05-0.1 mM; a concentration range insufficient for induction of StAR), were able to stimulate dramatic increases in both phospho-StAR (P-StAR) and steroid production. Human chorionic gonadotropin stimulation also resulted in a further enhancement in P-StAR and progesterone production when added to PMA-treated MA-10 cells. Similar results for tot-StAR and P-StAR expression were observed in primary cultures of immature rat Leydig cells treated with PMA and submaximal doses of (Bu)2cAMP. In summary, the present study demonstrates that basal activities of both PKC and PKA play important roles in the constitutive steroidogenic characteristics of R2C cells. This study also demonstrates for the first time a role for PMA-induced PKC in StAR protein regulation and the requirement for submaximal doses of cAMP to produce steroids in Leydig cells.

Responses of serum androgen and insulin resistance to metformin and pioglitazone in obese, insulin-resistant women with polycystic ovary syndrome

Severe insulin resistance is a key abnormality in obese women with polycystic ovary syndrome (PCOS). The purpose of this study was to evaluate whether pioglitazone decreases insulin resistance (IR) and hyperandrogenism to the same extent as metformin in obese women with PCOS who have not received any previous treatment. Fifty-two women with PCOS were randomly allocated to receive either pioglitazone (30 mg/d, n = 25) or metformin (850 mg three times daily, n = 27) and were assessed before and after 6 months. Body weight, body mass index, and waist to hip ratio increased significantly (P </= 0.05) after pioglitazone treatment but not after metformin treatment. Fasting serum insulin concentration (P < 0.001 for both drugs) and the area under the insulin curve during a 2-h oral glucose tolerance test decreased after pioglitazone (P < 0.002) or metformin (P < 0.05) treatment. IR (homeostasis model of assessment-IR index) decreased and insulin sensitivity (elevation of the quantitative insulin sensitivity check index and the fasting glucose to insulin ratio) increased (P </= 0.008) after treatment with either drug. Hirsutism (P < 0.05) and serum concentrations of free testosterone (P < 0.02) and androstenedione (P < 0.01) declined to a similar extent after treatment with the drugs. Treatment with pioglitazone or metformin was associated with the occurrence of pregnancy (n = 5 and n = 3, respectively). These results suggest that pioglitazone is as effective as metformin in improving insulin sensitivity and hyperandrogenism, despite an increase in body weight, body mass index, and the waist to hip ratio associated with pioglitazone.

Effects of metformin and rosiglitazone, alone and in combination, in nonobese women with polycystic ovary syndrome and normal indices of insulin sensitivity

OBJECTIVE

To determine whether insulin-sensitizing drugs would improve ovulation and T levels in women with polycystic ovary syndrome (PCOS), without clinical or biochemical criteria indicating insulin resistance and whether the combination of two distinct insulin-sensitizing drugs would be of any benefit over either drug alone.

DESIGN

Randomized controlled double-blind trial.

SETTING

A referral center in Caracas, Venezuela.

PATIENT(S)

One hundred twenty-eight nonobese PCOS women with normal indices of insulin sensitivity-that is, normal glucose tolerance, fasting insulin, peak insulin during an oral glucose tolerance test (OGTT), and fasting glucose-to-insulin ratio. Twenty-eight women were lost to follow-up initially and did not receive any intervention.

INTERVENTION(S)

One hundred women received twice daily one of the following for 6 months: metformin (850 mg), rosiglitazone (4 mg), combination of both drugs, or at least one placebo.

MAIN OUTCOME MEASURE(S)

Frequencies of ovulation and serum free T after 6 months.

RESULT(S)

Frequencies of ovulation were higher after treatment with an insulin-sensitizing drug (ovulations per subject in 6 months: metformin, 3.3; rosiglitazone, 2.4; and combination, 3.4) than with placebo (0.4). Ovulatory frequencies increased significantly more with metformin than rosiglitazone, and the combination was not more potent. After treatment, serum free-T levels were comparable among all active treatment groups (metformin: 2.34 pg/mL, rosiglitazone: 3.06 pg/mL, and combination: 2.39 pg/mL) and were significantly lower than in the placebo group (7.26 pg/mL). Compared with placebo, fasting insulin levels, area under the insulin curve during OGTT, the homeostatic model assessment of insulin sensitivity, and OGTT-derived insulin sensitivity index improved significantly after metformin or combination therapies but not after rosiglitazone.

CONCLUSION(S)

These findings suggest that insulin-sensitizing drugs increase ovulatory frequency and ameliorate hyperandrogenemia, even in nonobese women with PCOS who appear to have normal insulin sensitivity.

Alterations in mitogen-activated protein kinase kinase and extracellular regulated kinase signaling in theca cells contribute to excessive androgen production in polycystic ovary syndrome

We have investigated the involvement of the MAPK signaling pathway in increased androgen biosynthesis and CYP17 gene expression in women with polycystic ovary syndrome (PCOS). A comparison of MAPK kinase (MEK1/2) and ERK1/2 phosphorylation in propagated normal and PCOS theca cells, revealed that MEK1/2 phosphorylation was decreased more than 70%, and ERK1/2 phosphorylation was reduced 50% in PCOS cells as compared with normal cells. Infection with dominant-negative MEK1 increased CYP17 mRNA and dehydroepiandrosterone (DHEA) abundance, whereas constitutively active MEK1 reduced DHEA production and CYP17 mRNA abundance. Similarly, the MEK inhibitor, PD98059, increased CYP17 mRNA accumulation and CYP17 promoter activity to levels observed in PCOS cells. Remarkably, in theca cells maintained in the complete absence of insulin, ERK1/2 phosphorylation was decreased in PCOS theca cells as compared with normal theca cells, and CYP17 mRNA and DHEA synthesis were increased in PCOS theca cells. These studies demonstrate that in PCOS cells reduced levels of activated MEK1/2 and ERK1/2 are correlated with increased androgen production, irrespective of the insulin concentration. These findings implicate alterations in the MAPK pathway in the pathogenesis of excessive ovarian androgen production in PCOS.

Exaggerated 17-hydroxyprogesterone response to intravenous infusions of recombinant human LH in women with polycystic ovary syndrome

Studies using pharmacological gonadotropin stimulation suggest that ovarian steroidogenesis is abnormal in the polycystic ovary syndrome (PCOS). We assessed ovarian steroid secretion in response to near-physiological gonadotropin stimuli in 12 ovulatory controls and 7 women with PCOS. A gonadotropin-releasing hormone-receptor antagonist (ganirelix, 2 mg sc) was given to block endogenous LH secretion, followed by dexamethasone (0.75 mg orally) to suppress adrenal androgen secretion. After ganirelix injection (12 h), intravenous infusions of recombinant human LH (0, 10, 30, 100, and 300 IU; each over 8 min) were administered at 4-h intervals in a pseudorandomized (highest dose last) manner. Plasma LH, 17-hydroxyprogesterone (17-OHP), androstenedione, and testosterone were measured concurrently. LH dose-steroid response relationships (mean sex-steroid concentration vs. mean LH concentration over 4 h postinfusion) were examined for each subject. Linear regression of 17-OHP on LH yielded a higher (mean +/- SE) slope in PCOS (0.028 +/- 0.010 vs. 0.005 +/- 0.005, P < 0.05), whereas extrapolated 17-OHP at zero LH was similar. The slopes of other regressions did not differ from zero in either PCOS or controls. We conclude that near-physiological LH stimulation drives heightened 17-OHP secretion in patients with PCOS, suggesting abnormalities of early steps of ovarian steroidogenesis. With the exception of 17-OHP response in PCOS, no acute LH dose-ovarian steroid responses were observed in controls or PCOS. Defining the precise mechanistic basis of heightened precursor responsiveness to LH in PCOS will require further clinical investigation.

Requirement for proximal putative Sp1 and AP-2 cis-deoxyribonucleic acid elements in mediating basal and luteinizing hormone- and insulin-dependent in vitro transcriptional activation of the CYP17 gene in porcine theca cells

The cytochrome P450 17alpha-hydroxylase/C(17-20) lyase (CYP17) enzyme catalyzes the first committed step in androgen biosynthesis. In primary cultures of immature swine theca cells, LH and insulin induce CYP17 mRNA and incompletely processed heteronuclear RNA supraadditively over 2-6 h. To monitor in vitro transcriptional control by these two physiological signals, we cloned a -976 to +31-bp 5'-upstream region of the homologous CYP17 gene and fused it to a cytoplasmically targeted firefly luciferase minigene (CYP17/luc). LH and insulin individually stimulated transcriptional activity of transiently transfected CYP17/luc in theca cells by 2.7 +/- 0.31- and 2.5 +/- 0.24-fold over basal, respectively, at an optimal concentration (both 100 ng/ml) and time (6 h; both P < 0.01). Combined peptidyl agonists stimulated CYP17/luc by 6.6 +/- 1.2-fold (P < 0.001). To identify possible LH- and insulin-sensitive cis-acting DNA regulatory regions, we prepared four deletional constructs, -839, -473, -174, and -75/+35 bp 5' upstream of the transcriptional start site. Deletion from -976 to -839 bp decreased basal transcriptional activity by 89% and that stimulated by LH, insulin, and both effectors by 82%, 91%, and 78%, respectively (each P < 0.01). Further deletion to -473 bp conferred partial responsiveness to combined hormone stimulation, suggesting an intervening inhibitory sequence. Truncation to -174 bp and more proximally reduced basal CYP17/luc activity and hormonal action by more than 95% (P < 0.001). The marked loss of combined LH and insulin stimulation caused by deleting the region between -473 and -175 bp suggested the possible relevance of partially overlapping specificity protein-1 (Sp1) and activating protein-2 (AP-2)-like binding sites located between -193 and -180 bp. Point mutation of the proximal Sp1-like element in full-length -976/+31 CYP17/luc impaired basal transcription minimally (by 21%; P = NS) and stimulation by LH (76%), insulin (67%), and combined peptides (54%) significantly (each P < 0.05 vs. wild type). Mutation of the AP-2 site alone decreased basal CYP17/luc activity nonsignificantly (by 25%), but repressed stimulated transcriptional responses prominently, viz. to LH (57%), insulin (77%), and both effectors (82%; each P < 0.025 vs. wild type). Mutation of both sites inhibited basal and hormonally stimulated CYP17/luc activity by more than 95% (P < 0.001). At the level of second messenger signaling, insulin did not potentiate LH-enhanced cAMP accumulation, whereas a stable cAMP analog mimicked LH action and augmented insulin's stimulation of full-length and deletional fragments of CYP17/luc. In summary, LH and insulin stimulate transcriptional activity of a -976/+31 bp 5'-upstream cis-acting region of the (porcine) CYP17 gene individually and jointly in primary cultures of theca cells. Maximal transcriptional responsiveness to these peptide hormones requires proximal Sp1 and AP-2-like sequences -193 to -180 bp 5' upstream of the transcriptional start site. Exogenous cAMP mimics transcriptional up-regulation by LH and interacts analogously with insulin. These data are consistent with convergent drive of CYP17 gene expression by cAMP-protein kinase A and insulinsignaling pathways in untransformed theca cells.

Retention of estradiol negative feedback relationship to LH predicts ovulation in response to caloric restriction and weight loss in obese patients with polycystic ovary syndrome

The present study tests the hypothesis that specific endocrine, metabolic, and anthropometric features distinguish obese women with polycystic ovary syndrome (PCOS) who resume ovulation in response to calorie restriction and weight loss from those who do not. Fifteen obese (body mass index 39 +/- 7 kg/m(2)) hyperandrogenemic oligoovulatory patients undertook a very low calorie diet (VLCD), wherein each lost > or =10% of body weight over a mean of 6.25 mo. Body fat distribution was quantitated by magnetic resonance imaging. Hormones were measured in the morning at baseline, after 1 wk of VLCD, and after 10% weight loss. To monitor LH release, blood was sampled for 24 h at 10-min intervals before intervention and after 7 days of VLCD. Responders were defined a priori as individuals exhibiting two or more ovulatory cycles in the course of intervention, as corroborated by serum progesterone concentrations > or =18 nmol/l followed by vaginal bleeding. At baseline, responders had a higher sex hormone-binding globulin (SHBG) concentration but were otherwise indistinguishable from nonresponders. Body weight, the size of body fat depots, and plasma insulin levels declined to a similar extent in responders and nonresponders. Also, SHBG increased, and the free testosterone index decreased comparably. However, responders exhibited a significant decline of circulating estradiol concentrations (from 191 +/- 82 to 158 +/- 77 pmol/l, means +/- SD, P = 0.037) and a concurrent increase in LH secretion (from 104 +/- 42 to 140 +/- 5 U.l(-1).day(-1), P = 0.006) in response to 7 days of VLCD, whereas neither parameter changed significantly in nonresponders. We infer that evidence of retention of estradiol-dependent negative feedback on LH secretion may forecast follicle maturation and ovulation in obese patients with PCOS under dietary restriction.

Effect of rosiglitazone on insulin resistance, growth factors, and reproductive disturbances in women with polycystic ovary syndrome

OBJECTIVE

To evaluate the effects of rosiglitazone on insulin resistance, growth factors, and reproductive disturbances in women with polycystic ovary syndrome (PCOS).

DESIGN

Prospective study.

SETTING

Women with PCOS attending as outpatients of the Endocrine Division, Hospital Durand, Buenos Aires.

PATIENT(S)

Twenty-four insulin-resistant women with PCOS.

INTERVENTION(S)

Hormonal evaluations and a standardized oral glucose tolerance test before and after a 3-month trial of 4 mg of rosiglitazone daily.

MAIN OUTCOME MEASURE(S)

Serum LH, FSH, T, IGF-1, IGFBP-1, IGFBP-3, leptin, 17alpha-hydroxyprogesterone, insulin, and glucose concentrations. The area under insulin curve (AUC-insulin), the HOMA index (insulin resistance), the QUICKI index (insulin sensitivity), and the beta-cell function were calculated. Body mass index (BMI) and the waist/hip ratio were evaluated.

RESULT(S)

A significant decrease was observed in serum fasting insulin, AUC insulin, HOMA index, beta-cell function, IGF-1, LH, and waist/hip ratio. The QUICKI index and IGFBP-1 increased significantly. Serum sex hormone-binding globulin, androgens, leptin, IGFBP-3, and BMI remained unchanged. Twenty-two of 23 females had their menses restored, and three patients became pregnant. One patient was excluded because she became pregnant at the second month.

CONCLUSION(S)

Associated with the decrease in LH, rosiglitazone improved insulin-resistance parameters and normalized the menstrual cycle, which suggests that this drug could improve the endocrine-reproductive condition in insulin-resistant women with PCOS.

Insulin drives transcriptional activity of the CYP17 gene in primary cultures of swine theca cells

Insulin stimulates androgen biosynthesis and the accumulation of CYP17 mRNA and heterogeneous nuclear (hn) RNA in primary cultures of immature swine theca cells. To further assess insulinomimetic transcriptional control, we subcloned 1.007 kilobases (kb) of the 5'-upstream region of the CYP17 gene (-976 to +31 base pairs [bp] to the transcriptional start site) into a firefly-luciferase reporter construct. Insulin drove transcriptional activity of this probe in a time- and dose-dependent fashion, with maximal stimulation of 2.7- to 3.2-fold after insulin exposure (100 ng/ml) for 6 h. Progressive deletional constructs -839, -473, -174, and -75/+31 bp delineated expected reduction in responsiveness, except paradoxical gain of basal CYP17 promoter activity by the -473/+31-bp sequence. The latter suggests a possible intervening inhibitory sequence. Elimination of all sequences 5'-upstream to -174 bp markedly reduced basal transcriptional activity and abolished insulin action. Point mutation of a presumptive Sp1-like element located within -193/-180 bp inhibited basal and insulin-stimulated luciferase activity of the full-length promoter fragment by 40% and 67%, respectively. Disruption of a contiguous presumptive AP-2 site produced a comparable outcome. Combined mutation of the Sp1 and AP-2-like elements eliminated basal and insulin-potentiated CYP17 promoter activity. By Western analysis, insulin augmented cognate receptor phosphoprotein concentrations by 31-fold within 10 min. Chemical inhibitors of MEK-activated ERK1/2 attenuated insulin-enhanced CYP17 transcriptional activity by 76-80%. In summary, insulin drives transcriptional activity of a 5'-upstream regulatory sequence (-976 to +31 bp) of the swine CYP17 gene in primary cultures of theca cells, under a minimal requirement for combined activity of proximal (-193/180 bp) Sp1 and AP-2-like elements.