Evidence for insulin suppression of baseline luteinizing hormone in women with polycystic ovarian syndrome and normal women

Androgen Inhibition of Reproductive Neuroendocrine Function in Females and Transgender Males

Ovarian function is controlled by pituitary secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH), which in turn are governed by gonadotropin releasing hormone (GnRH) secreted from the brain. A fundamental principle of reproductive axis regulation is negative feedback signaling by gonadal sex steroids back to the brain to fine-tune GnRH and gonadotropin secretion. Endogenous negative feedback effects can be mimicked by exogenous steroid treatments, including androgens, in both sexes. Indeed, a growing number of clinical and animal studies indicate that high levels of exogenous androgens, in the typically male physiological range, can inhibit LH secretion in females, as occurs in males. However, the mechanisms by which male-level androgens inhibit GnRH and LH secretion still remain poorly understood, and this knowledge gap is particularly pronounced in transgender men (individuals designated female at birth but identifying as male). Indeed, many transgender men take long-term gender-affirming hormone therapy that mimics male-level testosterone levels. The impact of such gender-affirming testosterone on the reproductive axis, both at the ovarian and neuroendocrine level, is a long-understudied area that still requires further investigation. Importantly, the few concepts of androgen actions in females mostly come from studies of polycystic ovary syndrome, which does not recapitulate a similar androgen milieu or a pathophysiology of inhibited LH secretion as occurs in testosterone-treated transgender men. This review summarizes clinical evidence indicating that exogenous androgens can impair neuroendocrine reproductive function in both female individuals and transgender men and highlights emerging experimental data supporting this in recently developed transgender rodent models.

Obesity-Related Hypogonadism in Women

Obesity-related hypogonadotropic hypogonadism is a well-characterized condition in men (termed male obesity-related secondary hypogonadism; MOSH); however, an equivalent condition has not been as clearly described in women. The prevalence of polycystic ovary syndrome (PCOS) is known to increase with obesity, but PCOS is more typically characterized by increased gonadotropin-releasing hormone (GnRH) (and by proxy luteinizing hormone; LH) pulsatility, rather than by the reduced gonadotropin levels observed in MOSH. Notably, LH levels and LH pulse amplitude are reduced with obesity, both in women with and without PCOS, suggesting that an obesity-related secondary hypogonadism may also exist in women akin to MOSH in men. Herein, we examine the evidence for the existence of a putative non-PCOS "female obesity-related secondary hypogonadism" (FOSH). We précis possible underlying mechanisms for the occurrence of hypogonadism in this context and consider how such mechanisms differ from MOSH in men, and from PCOS in women without obesity. In this review, we consider relevant etiological factors that are altered in obesity and that could impact on GnRH pulsatility to ascertain whether they could contribute to obesity-related secondary hypogonadism including: anti-Müllerian hormone, androgen, insulin, fatty acid, adiponectin, and leptin. More precise phenotyping of hypogonadism in women with obesity could provide further validation for non-PCOS FOSH and preface the ability to define/investigate such a condition.

Insulin resistance and idiopathic hirsutism: A systematic review, meta-analysis, and meta-regression

OBJECTIVES

This study aimed to evaluate the Standardized Mean Difference (SMD) of insulin resistance parameters in women with IH, compared to healthy and polycystic ovary syndrome (PCOS) controls.

MATERIALS AND METHODS

PubMed, Scopus, Web of Sciences, and Embase were searched for retrieving studies published up to November 2021 investigating the insulin resistance parameters in women with IH, compared to control groups. Meta-regression and subgroup analysis were conducted to evaluate the effect of potential confounders, such as age, BMI, and study design.

RESULTS

A meta-analysis of 20 studies revealed that higher SMDs of fasting insulin (SMD: 0.58; 95% CI: 0.10, 1.06), HOMA-IR (SMD: 0.53; 95% CI: 0.09, 0.97), and FBS levels (SMD: 0.11; 95% CI: 0.03, 0.19) in women with IH than healthy. It also showed that the SMD of HOMA-IR was significantly lower in women with IH than PCOS patients (SMD: -0.49; 95% CI: -0.88, -0.09). A subgroup analysis of cross-sectional studies showed higher SMDs of fasting insulin (SMD: 0.86; 95% CI: 0.05, 1.68), HOMA-IR (SMD: 0.83; 95% CI: 0.01, 1.64), and FBS levels (SMD: 0.14; 95% CI: 0.00, 0.28) in women with IH than healthy, whereas there was no difference in the SMD of these metabolic parameters between IH and PCOS groups, except for SMD of HOMA-IR (SMD: -0.22; 95% CI: -0.42, -0.02).

CONCLUSIONS

The results of the study demonstrate that insulin resistance parameters are related to IH, although insulin resistance values in women with IH are not as high as in patients with PCOS. According to the results of the study, measuring these metabolic parameters can be beneficial to evaluate all hirsute women with IH.

Wet-cupping on calf muscles in polycystic ovary syndrome: a quasi-experimental study

OBJECTIVES

Current modalities for treating polycystic ovary syndrome (PCOS) are not curative and using them for a long period is associated with adverse effects. According to Persian Medicine recommendations, wet cupping on calf muscles can induce menstrual bleeding. In the present study, the effect of wet-cupping (traditional bleeding from capillary vessels) was assessed on menstrual cycles (as primary outcome), hirsutism, and laboratory manifestation of PCOS.

METHODS

A quasi-experimental study was conducted from 2016/5/21 until 2017/5/20 on 66 PCOS women within the age range of 20-40 years and a menstrual interval of at least 60 days during the last year. Participants' calf muscles were cupped on day 26 of their last menstruation cycle following the Persian Medicine recommendations. They were followed for 12 weeks and a menstruation history and physical examination was done twice (4 and 12 weeks after wet cupping). Insulin Resistance (IR) and Free Androgen Index (FAI) were evaluated at baseline and end of the study.

RESULTS

Wet-cupping on calf muscles significantly improved menstrual cycles' frequency 0.37(95% CI: 0.13, 0.51), p-value=0.001 and hirsutism after 4 and 12 weeks of intervention were -1.9 (95% CI: -2.5, -0.5), p-value<0.001 and -1.4(95% CI: -2.1, -0.8), p-value<0.001, respectively. While it was not significant in changing the IR and FAI. About 33% of participants suffered from mild temporary discomforts (which were resolved within a few minutes of rest) and 9% reported mild long-term side effects.

CONCLUSIONS

It is considered that wet-cupping on calf muscles can be propounded as an optional treatment of PCOS for those not willing to use chemical medication.

Androgen Suppresses In Vivo and In Vitro LH Pulse Secretion and Neural Kiss1 and Tac2 Gene Expression in Female Mice

Androgens can affect the reproductive axis of both sexes. In healthy women, as in men, elevated exogenous androgens decrease gonad function and lower gonadotropin levels; such circumstances occur with anabolic steroid abuse or in transgender men (genetic XX individuals) taking androgen supplements. The neuroendocrine mechanisms by which endogenous or exogenous androgens regulate gonadotropin release, including aspects of pulsatile luteinizing hormone (LH) secretion, remain unknown. Because animal models are valuable for interrogating neural and pituitary mechanisms, we studied effects of androgens in the normal male physiological range on in vivo LH secretion parameters in female mice and in vitro LH secretion patterns from isolated female pituitaries. We also assessed androgen effects on hypothalamic and gonadotrope gene expression in female mice, which may contribute to altered LH secretion profiles. We used a nonaromatizable androgen, dihydrotestosterone (DHT), to isolate effects occurring specifically via androgen receptor (AR) signaling. Compared with control females, DHT-treated females exhibited markedly reduced in vivo LH pulsatility, with decreases in pulse frequency, amplitude, peak, and basal LH levels. Correlating with reduced LH pulsatility, DHT-treated females also exhibited suppressed arcuate nucleus Kiss1 and Tac2 expression. Separate from these neural effects, we determined in vitro that the female pituitary is directly inhibited by AR signaling, resulting in lower basal LH levels and reduced LH secretory responses to gonadotropin-releasing hormone pulses, along with lower gonadotropin gene expression. Thus, in normal adult females, male levels of androgen acting via AR can strongly inhibit the reproductive axis at both the neural and pituitary levels.

GLUT1-mediated glycolysis supports GnRH-induced secretion of luteinizing hormone from female gonadotropes

The mechanisms mediating suppression of reproduction in response to decreased nutrient availability remain undefined, with studies suggesting regulation occurs within the hypothalamus, pituitary, or gonads. By manipulating glucose utilization and GLUT1 expression in a pituitary gonadotrope cell model and in primary gonadotropes, we show GLUT1-dependent stimulation of glycolysis, but not mitochondrial respiration, by the reproductive neuropeptide GnRH. GnRH stimulation increases gonadotrope GLUT1 expression and translocation to the extracellular membrane. Maximal secretion of the gonadotropin Luteinizing Hormone is supported by GLUT1 expression and activity, and GnRH-induced glycolysis is recapitulated in primary gonadotropes. GLUT1 expression increases in vivo during the GnRH-induced ovulatory LH surge and correlates with GnRHR. We conclude that the gonadotropes of the anterior pituitary sense glucose availability and integrate this status with input from the hypothalamus via GnRH receptor signaling to regulate reproductive hormone synthesis and secretion.

Targeting Metabolic Consequences of Insulin Resistance in Polycystic Ovary Syndrome by D-chiro-inositol and Emerging Nutraceuticals: A Focused Review

Polycystic ovary syndrome (PCOS) is a complex disorder associated with ovarian dysfunction, infertility, menstrual irregularity, and hormonal impairments. Over the last decade, several studies have shown that some PCOS women have insulin resistance (InsR) and hyperinsulinemia, apart from being overweight or obese. Therefore, a crucial clinical aspect is that PCOS patients might develop glucose intolerance and type 2 diabetes. Insulin-sensitizing drugs have been used as first-line treatment to improve hyperinsulinemia in women with PCOS. Although reducing PCOS symptoms and signs, several used insulin-sensitizer drugs may induce side effects, which reduces compliance. D-chiro-inositol (DCI), which is a naturally occurring stereoisomer of inositol, has been classified as an insulin-sensitizer and seems to mitigate multiple InsR-related metabolic alterations in PCOS with a safe profile. However, according to a multi-targeted design, the supplementation with DCI can be synergistically integrated by combining other potential insulin-sensitizing drugs and/or nutraceuticals. The literature provides the initial support for using several unexplored nutraceutical interventions that may target relevant metabolic abnormalities associated with InsR in PCOS. With a need to promote interest in clinical research, this review aims to discuss the efficacy of DCI and the role of emerging nutraceuticals for managing InsR in PCOS.

Effect of phlebotomy versus oral contraceptives containing cyproterone acetate on the clinical and biochemical parameters in women with polycystic ovary syndrome: a randomized controlled trial

BACKGROUND

Reduction of the body iron stores can improve hyperandrogenemia and insulin resistance. This study aimed to compare clinical and para-clinical responses to the treatment of phlebotomy using oral contraceptive pills (OCs) containing cyproterone acetate in women with PCOS.

METHODS

In this randomized clinical trial, 64 patients with PCOS were randomly assigned to the phlebotomy and OCs groups (n = 32 in each group). The intervention group, using a single treatment procedure, underwent venesection of 450 mL of whole blood at the early follicular phase of the spontaneous or progesterone-induced menstrual cycle. The control group received OCs pills for 3 months from the 1th day of spontaneous or progesterone-induced menstrual cycle onwards for 3 weeks, followed by a pill-free interval of 7 days. The women were evaluated after the 3-month intervention. The primary outcome measure was a change in the HOMA-IR and free androgen index (FAI). Secondary outcomes were changes in the Ferriman-Gallwey (FG) score and other clinical, biochemical and hormonal changes from the baseline (pre-treatment) to week 12.

RESULTS

In the phlebotomy group, 27 (84.3%) and in the OCs group 30 (93.7%) of the women completed the 3-month follow-up. The median HOMA-IR significantly decreased from 3.5 to 2.7 in the phlebotomy, and from 3.1 to 2.8 in the OCs group, and the changes were comparable between the groups. Median changes in the FAI significantly decreased in both groups, but the differences were not statistically significant between the groups (P = 0.061). With regard to secondary outcomes, mean FG scores in both groups significantly decreased [from 16.8 (6) to 13.3 (7.4), P < 0.028] in the phlebotomy group and [from 14.3 (7) to 9.8 (7.6) in the OCs group, P = 0.001] after 3 months of treatment, but such changes had no statistically significant differences between the groups. During treatment, menstrual cycles became regular in all women in the OCs group and in 12.27 (44.4%) of the women in the phlebotomy group, and the difference was statistically significant (P = 0.001). Despite no statistically significant differences in lipid profiles between the groups at the baseline, triglycerides were significantly higher in the OCs group compared to the phlebotomy at end of follow up (p = 0.019).

CONCLUSION

Both treatment modalities had similar beneficial effects on insulin resistance and on androgenic profiles. However, OCs was reported more effective in treating menstrual irregularities and phlebotomy had less adverse effects on triglyceride concentrations.

TRIAL REGISTRATION

Code: IRCT2013080514277N1 .

The relationship between clinical and biochemical characteristics and quality of life in patients with polycystic ovary syndrome

BACKGROUND AND OBJECTIVE

While has been well demonstrated that clinical characteristics of polycystic ovary syndrome (PCOS) are associated with an impaired quality of life (QoL) in patients, it is unclear that whether the biochemical aspects of PCOS can influence their QoL. We aimed to investigate the relationship between clinical and biochemical characteristics, and various domains of QoL in patients with PCOS.

DESIGN

A cross-sectional study.

PATIENTS AND MEASUREMENTS

We assessed the association between clinical and biochemical characteristics and QoL domains (psychosocial-emotional, fertility, sexual function, and obesity-menstrual) in a total of 211 women with PCOS using a specific health-related quality-of-life questionnaire for PCOS patients.

RESULTS

Our findings showed positive significant association of QoL with age, and its negative significant associations with BMI, hirsutism and infertility (P < 0.05). We also found a negative association between FAI and total QoL (r = -0.14; P = 0.042) and domains of hirsutism (r = -0.14; P = 0.045) and obesity-menstrual (r = -0.23; P = 0.001). DHEAS was positively associated with the sexual function aspect of QoL (r = 0.20; P = 0.043). There were no significant associations between QoL and other hormonal parameters including LH to FSH ratio and total testosterone (tT). Significant associations were found between triglycerides (TG), total cholesterol (TC), LDL and HDL cholesterol, and domain of obesity-menstrual of QoL. HOMA-IR was significantly related to all QoL domains except self-image and hirsutism.

CONCLUSION

Although biochemical markers can influence QoL in patients with PCOS, clinical manifestations of this syndrome such as obesity, infertility and hirsutism seem to play roles in worsening QoL, in particular for psychosocial domains. Hence, clinicians should regularly assess the clinical and psychosocial dimensions of PCOS as well as biochemical aspects.

Induction of Stress Signaling In Vitro and Suppression of Gonadotropin Secretion by Free Fatty Acids in Female Mouse Gonadotropes

An emerging body of evidence supports the concept that the pituitary is a site for integration of multiple physiological and metabolic signals that inform and modulate endocrine pathways. Multiple endocrine mediators of energy balance and adiposity are known to impinge on the neuroendocrine axis regulating reproduction. Observations in humans show that obesity is correlated with decreased gonadotropin secretion, and studies have also suggested that pituitary sensitivity to stimulation by gonadotropin-releasing hormone (GnRH) is decreased in obese individuals. Free fatty acids are a potential mediator of adiposity and energy balance, but their impact as an endocrine modulator of pituitary function has not been closely examined. We evaluated the impact of free fatty acids on a pituitary gonadotrope cell line and in primary pituitary cultures of female mice. We show that increasing physiologically relevant doses of the monounsaturated ω-9 fatty acid oleate induces cellular stress and increases production of reactive oxygen species in a mouse gonadotrope cell line. In contrast, the unsaturated ω-3 α-linolenic and ω-6 linoleic fatty acids do not have this effect. Additionally, oleate can activate immediate-early gene expression independent of GnRH stimulation but has a negative impact on GnRH induction and expression of the gonadotropin subunit gene Lhb. Further, oleate suppresses gonadotropin secretion in response to pulsatile stimulation by GnRH. These results indicate that free fatty acids can directly alter gonadotropin gene expression and secretion in response to GnRH and may provide a link between energy sensing and reproduction.

Acute recapitulation of the hyperinsulinemia and hyperlipidemia characteristic of metabolic syndrome suppresses gonadotropins

OBJECTIVE

To determine the effect of lipid/heparin versus saline infusion, with or without concurrent euglycemic hyperinsulinemia, on serum follicle-stimulating hormone (FSH) and luteinizing hormone (LH). Obesity is associated with hyperlipidemia, insulin resistance, and relative hypogonadotropic hypogonadism. It was hypothesized that acutely elevated fatty acids and insulin would impair gonadotropin secretion.

METHODS

Regularly cycling women and men without obesity underwent a crossover 6-hour infusion study over four visits. Participants received infusions of saline-control, lipid/heparin, insulin, and lipid/heparin plus insulin. Serum FSH and LH were measured by immunoassay.

RESULTS

In women (n = 10), infusion of lipid plus insulin significantly reduced LH, from 4.6 IU/L (3.7-5.4) (mean [95% confidence interval]) to 3.3 IU/L (2.3-4.4); P = 0.03, and FSH, from 3.9 IU/L (3.2-4.6) to 3.1 IU/L (2.3-3.8); P = 0.03, compared to saline-control. Similarly, in men (n = 10), LH, 3.3 IU/L (2.4-4.1), and FSH, 2.1 IU/L (1.4-2.8), were significantly reduced after the combined infusion (2.2 [1.3-3.1] IU/L and 1.5 [0.8-2.1] IU/L; P = 0.03, P = 0.02, respectively). Neither lipid nor insulin alone significantly impacted gonadotropin levels compared to saline-control.

CONCLUSIONS

Hyperinsulinemia combined with elevated lipids acutely suppresses LH and FSH, providing a possible mechanism underlying the relative hypogonadotropic hypogonadism of obesity. Effects of insulin on the hypothalamic-pituitary-gonadal axis may be dependent on the concomitant metabolic environment.

Reactive Oxygen Species Link Gonadotropin-Releasing Hormone Receptor Signaling Cascades in the Gonadotrope

Biological rhythms lie at the center of regulatory schemes that control many aspects of living systems. At the cellular level, meaningful responses to external stimuli depend on propagation and quenching of a signal to maintain vigilance for subsequent stimulation or changes that serve to shape and modulate the response. The hypothalamus-pituitary-gonad endocrine axis that controls reproductive development and function relies on control through rhythmic stimulation. Central to this axis is the pulsatile stimulation of the gonadotropes by hypothalamic neurons through episodic release of the neuropeptide gonadotropin-releasing hormone. Alterations in pulsatile stimulation of the gonadotropes result in differential synthesis and secretion of the gonadotropins LH and FSH and changes in the expression of their respective hormone subunit genes. The requirement to amplify signals arising from activation of the gonadotropin-releasing hormone (GnRH) receptor and to rapidly quench the resultant signal to preserve an adaptive response suggests the need for rapid activation and feedback control operating at the level of intracellular signaling. Emerging data suggest that reactive oxygen species (ROS) can fulfill this role in the GnRH receptor signaling through activation of MAP kinase signaling cascades, control of negative feedback, and participation in the secretory process. Results obtained in gonadotrope cell lines or other cell models indicate that ROS can participate in each of these regulatory cascades. We discuss the potential advantage of reactive oxygen signaling for modulating the gonadotrope response to GnRH stimulation and the potential mechanisms for this action. These observations suggest further targets of study for regulation in the gonadotrope.

The Pathogenesis of Polycystic Ovary Syndrome (PCOS): The Hypothesis of PCOS as Functional Ovarian Hyperandrogenism Revisited

Polycystic ovary syndrome (PCOS) was hypothesized to result from functional ovarian hyperandrogenism (FOH) due to dysregulation of androgen secretion in 1989-1995. Subsequent studies have supported and amplified this hypothesis. When defined as otherwise unexplained hyperandrogenic oligoanovulation, two-thirds of PCOS cases have functionally typical FOH, characterized by 17-hydroxyprogesterone hyperresponsiveness to gonadotropin stimulation. Two-thirds of the remaining PCOS have FOH detectable by testosterone elevation after suppression of adrenal androgen production. About 3% of PCOS have a related isolated functional adrenal hyperandrogenism. The remaining PCOS cases are mild and lack evidence of steroid secretory abnormalities; most of these are obese, which we postulate to account for their atypical PCOS. Approximately half of normal women with polycystic ovarian morphology (PCOM) have subclinical FOH-related steroidogenic defects. Theca cells from polycystic ovaries of classic PCOS patients in long-term culture have an intrinsic steroidogenic dysregulation that can account for the steroidogenic abnormalities typical of FOH. These cells overexpress most steroidogenic enzymes, particularly cytochrome P450c17. Overexpression of a protein identified by genome-wide association screening, differentially expressed in normal and neoplastic development 1A.V2, in normal theca cells has reproduced this PCOS phenotype in vitro. A metabolic syndrome of obesity-related and/or intrinsic insulin resistance occurs in about half of PCOS patients, and the compensatory hyperinsulinism has tissue-selective effects, which include aggravation of hyperandrogenism. PCOS seems to arise as a complex trait that results from the interaction of diverse genetic and environmental factors. Heritable factors include PCOM, hyperandrogenemia, insulin resistance, and insulin secretory defects. Environmental factors include prenatal androgen exposure and poor fetal growth, whereas acquired obesity is a major postnatal factor. The variety of pathways involved and lack of a common thread attests to the multifactorial nature and heterogeneity of the syndrome. Further research into the fundamental basis of the disorder will be necessary to optimally correct androgen levels, ovulation, and metabolic homeostasis.

Is the association between insulin resistance and diabetogenic haematopoietically expressed homeobox (HHEX) polymorphism (rs1111875) affected by polycystic ovary syndrome status?

Polycystic ovary syndrome (PCOS) is frequently accompanied by insulin resistance (IR). The aim of the present study was to investigate whether the genetic association between insulin resistance and two single nucleotide polymorphisms (SNPs), namely rs7903146 (C/T) in transcription factor 7-like 2 (TCF7L2) and rs1111875 (A/G) in haematopoietically expressed homeobox (HHEX), is affected by PCOS status in Iranian women. The study participants consisted of 582 women with PCOS (cases) referred to the Reproductive Endocrinology Research Center and 504 subjects without PCOS (controls), randomly selected from the Tehran Lipid and Glucose Study. Cases and controls were further subdivided to two groups according to IR status: those with and without IR. IR was identified on the basis of homeostasis model assessment of insulin resistance (HOMA-IR) ≥2.63. The SNPs in TCF7L2 and HHEX were genotyped by polymerase chain reaction-restriction fragment length polymorphism. There were no significant differences in the distribution of genotypes and alleles between cases and controls (P<0.05). Among cases, the prevalence of the CC, CT and TT genotypes was 37.8%, 46.3% and 15.9%, respectively, whereas the prevalence of the AA, AG and GG genotypes was 13.5%, 46.1% and 40.4%, respectively. In the control group, the prevalence of the CC, CT and TT genotypes was 32.2%, 53.9% and 13.9%, respectively, whereas the prevalence of the AA, AG and GG genotypes was 11.3%, 48.6% and 40.0%, respectively. After adjustment for age and body mass index, the probability of IR was decreased by 49% among carriers of the A allele in the control group (95% confidence interval 0.33-0.78; P=0.002). The findings of the present study suggest that the association between IR and diabetogenic polymorphisms may be affected by PCOS status.

Trend of Cardio-Metabolic Risk Factors in Polycystic Ovary Syndrome: A Population-Based Prospective Cohort Study

OBJECTIVE

To see the changes of cardio-metabolic risk factors overtime in polycystic ovary syndrome vs. control women.

METHODS

This study was conducted on 637 participants (85 PCOS and 552 control reproductive aged, 18-45 years) of Tehran Lipid and Glucose Study (TLGS), an ongoing population-based cohort study with 12 years of follow-up. The cardiovascular risk factors of these groups were assessed in three-year intervals using standard questionnaires, history taking, anthropometric measures, and metabolic/endocrine evaluation. Generalized estimating equation was used to analyze the data.

RESULTS

Overall mean of insulin (3.55, CI: 0.66-6.45), HOMA-IR (0.63, CI: 0.08-1.18), and HOMA-β (45.90, CI: 0.86-90.93) were significantly higher in PCOS than in healthy women after adjustment for age, BMI, and baseline levels. However, the negative interaction (follow-up years × PCOS status) of PCOS and normal women converged overtime. Comparing third follow-up with first, insulin and HOMA-IR decreased 10.6% and 5%, respectively in PCOS women; and increased 6.7% and 14.6%, respectively in controls (P<0.05). The results did not show any significant result for other cardio-metabolic variables including WC, lipid profile, FPG, 2-h PG, SBP, and DBP.

CONCLUSION

While the insulin level and insulin resistance rate were higher in reproductive aged PCOS than in healthy women, the difference of these risk factors decreased overtime. Thus, the metabolic consequences of PCOS women in later life may be lower than those initially anticipated.

GnRH Regulates Gonadotropin Gene Expression Through NADPH/Dual Oxidase-Derived Reactive Oxygen Species

The appropriate control of synthesis and secretion of the gonadotropin hormones LH and FSH by pituitary gonadotropes is essential for the regulation of reproduction. The hypothalamic neuropeptide GnRH is the central regulator of both processes, coordinating secretion with transcription and translation of the gonadotropin hormone subunit genes. The MAPK family of second messengers is strongly induced in gonadotropes upon GnRH stimulation, and multiple pathways activate these kinases. Intracellular reactive oxygen species participate in signaling cascades that target MAPKs, but also participate in signaling events indicative of cell stress. The NADPH oxidase (NOX)/dual oxidase (DUOX) family is a major enzymatic source of intracellular reactive oxygen, and we show that GnRH stimulation of mouse primary pituitary cells and the LβT2 gonadotrope cell line elevates intracellular reactive oxygen via NOX/DUOX activity. Mouse pituitary and LβT2 cells abundantly express NOX/DUOX and cofactor mRNAs. Pharmacological inhibition of NOX/DUOX activity diminishes GnRH-stimulated activation of MAPKs, immediate-early gene expression, and gonadotropin subunit gene expression. Inhibitor studies implicate the calcium-activated DUOX family as a major, but not exclusive, participant in GnRH signaling. Knockdown of DUOX2 in LβT2 cells reduces GnRH-induced Fshb, but not Lhb mRNA levels, suggesting differential sensitivity to DUOX activity. Finally, GnRH pulse-stimulated FSH and LH secretion are suppressed by inhibition of NOX/DUOX activity. These results indicate that reactive oxygen is a potent signaling intermediate produced in response to GnRH stimulation and further suggest that reactive oxygen derived from other sources may influence the gonadotrope response to GnRH stimulation.

Symptom patterns and phenotypic subgrouping of women with polycystic ovary syndrome: association between endocrine characteristics and metabolic aberrations

STUDY QUESTION

What are the potential endocrine characteristics related to risk and severity of metabolic disturbances in women with polycystic ovary syndrome (PCOS)?

SUMMARY ANSWER

Women with PCOS could be subtyped into four subgroups according to heterogeneous endocrine characteristics and the major predictive endocrine factors for metabolic aberrations among different subgroups were free androgen index (FAI) and luteinizing hormone (LH) levels.

WHAT IS KNOWN ALREADY

Women diagnosed with PCOS present with highly heterogeneous phenotypes, including endocrine and metabolic aberrations. Different strategies have been proposed to predict the metabolic outcomes but whether the endocrine factors can solely predict the metabolic aberrations is still inconclusive.

STUDY DESIGN, SIZE, DURATION

A cross-sectional study including 460 patients recruited from a reproductive endocrinology outpatient clinic of a tertiary medical center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Patients with PCOS diagnosed according to the 2003 Rotterdam criteria were studied. Clinical history recorded by questionnaires, anthropometric measurements, biochemistry tests after an overnight fast, and pelvic ultrasonography were collected from all patients.

MAIN RESULTS AND THE ROLE OF CHANCE

Applying a matrix visualization and clustering approach (generalized association plots), the patients were divided into four distinct clusters according to the correlation with four endocrine parameters. Each cluster exhibited specific endocrine characteristics and the prevalence of metabolic syndrome (MS) was significantly different among the clusters (P < 0.0001). The high-risk subgroups for MS included one cluster with higher mean (SD) FAI (39.6 (14.7) in cluster 4), and another one with lower mean (SD) FAI (10 (6.4) in cluster 2). A common endocrine characteristic of these two metabolically unhealthy clusters was relatively lower LH level. Contrarily, higher LH level (≧15 mIU/ml) during early follicular phase was found to be the best indicator of the metabolically healthy cluster (cluster 1). While high FAI level did correlate with more severe metabolic aberrations, high LH level showed better predictive value than low FAI level to become a metabolically healthy cluster.

LIMITATIONS, REASONS FOR CAUTION

The results should be applied to other populations with caution due to racial or environmental differences. Another limitation is a lack of normal non-PCOS control in our study.

WIDER IMPLICATIONS OF THE FINDINGS

Stratifying women with PCOS into meaningful subtypes could provide a better understanding of related risk factors and potentially enable the design and delivery of more effective screening and treatment intervention.

STUDY FUNDING/COMPETING INTERESTS

This study was supported by grant NSC 100-2314-B002-027-MY3 from the National Science Council of Taiwan.

TRIAL REGISTRATION NUMBER

Nil.

Prevalence and impact of hyperandrogenemia in 1,218 women with polycystic ovary syndrome

Hyperandrogenemia modifies phenotypic characteristics of women with polycystic ovary syndrome (PCOS). The aim of the present study is to evaluate (a) the prevalence of hyperandrogenemia in PCOS women (Rotterdam criteria) and (b) the impact of either the degree or the type of hyperandrogenemia on phenotype. Anthropometric, clinical, hormonal, metabolic and ultrasound characteristics of 1,218 women with PCOS were analyzed in this cross-sectional study. The prevalence of hyperandrogenemia was 58.8 %. Women with hyperandrogenemia had higher luteinizing hormone (LH), follicle-stimulating hormone (FSH), free androgen index, lower sex-hormone-binding globulin (SHBG) and fasting glucose levels compared to women with normal androgens (p < 0.001 for all comparisons; p = 0.001 for fasting glucose). Regarding the presence of isolated hyperandrogenemia, the group with only elevated testosterone levels was termed GT and an analogous categorization was made for dehydroepiandrosterone sulfate (GD) and androstenedione (Δ4) (GΔ4), respectively. GT, GD and GΔ4 comprised the 17.2, 7.6 and 4.1 % of total cohort, respectively. These groups differed significantly between them in LH, LH/FSH ratio, and SHBG (p < 0.001). Hyperandrogenemia is found in almost 60 % of women with PCOS (Rotterdam criteria), and it affects hormonal characteristics of these women such as LH and SHBG values. Regarding the impact of isolated hyperandrogenemia on PCOS characteristics, it appears that Δ4 and testosterone elevations are associated with increased LH levels.

The regulation of reproductive neuroendocrine function by insulin and insulin-like growth factor-1 (IGF-1)

The mammalian reproductive hormone axis regulates gonadal steroid hormone levels and gonadal function essential for reproduction. The neuroendocrine control of the axis integrates signals from a wide array of inputs. The regulatory pathways important for mediating these inputs have been the subject of numerous studies. One class of proteins that have been shown to mediate metabolic and growth signals to the CNS includes Insulin and IGF-1. These proteins are structurally related and can exert endocrine and growth factor like action via related receptor tyrosine kinases. The role that insulin and IGF-1 play in controlling the hypothalamus and pituitary and their role in regulating puberty and nutritional control of reproduction has been studied extensively. This review summarizes the in vitro and in vivo models that have been used to study these neuroendocrine structures and the influence of these growth factors on neuroendocrine control of reproduction.

Lipid accumulation product and insulin resistance in Iranian PCOS prevalence study

OBJECTIVE

To evaluate diagnostic accuracy of lipid accumulation product (LAP) index as a marker of insulin resistance in a community-based population with polycystic ovary syndrome (PCOS), compared with healthy women.

METHODS

Anthropometric measurements, biochemical parameters, LAP index and insulin resistance (IR) were compared in 134 PCOS subjects and 414 healthy women recruited from 1126 reproductive aged women (18-45 years), participants of the Iranian PCOS Prevalence Study. LAP was defined as [WC (cm)-58] ×TG (mmol/l)]. PCOS was diagnosed using the Rotterdam criteria, and IR was defined using the homeostatic model assessment IR. LAP, body mass index (BMI), waist circumference (WC) and waist-to-hip ratio (WHR) were compared using the two-tailed Spearman rank correlation test and analysing the receiver operating characteristic (ROC) curves for IR.

RESULTS

Among the PCOS subjects, the mean ± SD age, BMI, WC and WHR were 32·2 ± 7·7 years, 26·8 ± 5·8 kg/m(2) , 85·2 ± 13·2 cm and 0·80 ± 0·06, respectively, and the median (IQ25-75) of LAP index was 34·03 (17·8-66·3). There was significant correlation between HOMA-IR index and LAP in patients with PCOS (r = 0·41; P < 0·001). Also, ROC curves analysis revealed that the optimal cut-off value for LAP to define the presence of IR was 34·1 (sensitivity: 75%; specificity: 58%). LAP showed the highest area under curve (AUC) (P < 0·001).

CONCLUSION

Among PCOS subjects, LAP index has the strongest diagnostic accuracy for detection of IR in comparison with BMI, WC and WHR.

Insulin: its role in the central control of reproduction

Insulin has long been recognized as a key regulator of energy homeostasis via its actions at the level of the brain, but in addition, plays a role in regulating neural control of reproduction. In this review, we consider and compare evidence from animal models demonstrating a role for insulin for physiological control of reproduction by effects on GnRH/LH secretion. We also review the role that insulin plays in prenatal programming of adult reproduction, and consider specific candidate neurons in the adult hypothalamus by which insulin may act to regulate reproductive function. Finally, we review clinical evidence of the role that insulin may play in adult human fertility and reproductive disorders. Overall, while insulin appears to have a significant impact on reproductive neuroendocrine function, there are many unanswered questions regarding its precise sites and mechanisms of action, and their impact on developing and adult reproductive neuroendocrine function.

Lack of association of INS VNTR polymorphism with polycystic ovary syndrome: a meta-analysis

PURPOSE

An association between the INS VNTR polymorphisms and polycystic ovary syndrome (PCOS) susceptibility has been reported in previous studies, but the results were inconsistent. This study was conducted to explore this association using meta-analysis.

METHODS

PubMed, Embase, and China National Knowledge Infrastructure (CNKI) were searched according to predefined criteria for all relevant studies published up to August 2013. Four genetic models, together with odds ratios (ORs) and 95 % confidence intervals (CI), were calculated. Subgroup analyses were performed by ethnicity, anovulatory PCOS, and Hardy-Weinberg equilibrium (HWE) in the controls.

RESULTS

In total, 13 case-control studies, including 1,767 cases and 4,108 controls, were included. No significant association was detected in overall population in all models (III/III vs. I/I: OR = 1.200, 95%CI = 0.866-1.664, P=0.277; I/III vs. I/I: OR = 1.041, 95%CI = 0.880-1.232, P=0.637; III/III + I/III vs. I/I: OR = 1.191, 95%CI = 0.912-1.554, P=0.199; III/III vs. I/III + I/I: OR = 1.100, 95%CI = 0.816-1.484, P=0.531), the same as in Caucasian and Asian populations. When the studies were limited to conform to HWE, the results remained persistent and robust. The anovulation subgroup showed significantly elevated risk in the I/III vs. I/I (OR = 1.460, 95%CI = 1.017-2.095, P=0.040).

CONCLUSIONS

This meta-analysis revealed no significant association between INS VNTR polymorphisms and the risk of PCOS in the overall population, while it supported that variance may be associated with susceptibility to PCOS with anovulation. Further confirmation is needed from more well-designed and larger studies.

The circadian variation in Anti-Müllerian hormone in patients with polycystic ovary syndrome differs significantly from normally ovulating women

Obective

To improve the biologic understanding of the Polycystic Ovarian Syndrome (PCOS) condition by examining the circadian variation and relationship between Anti Müllerian Hormone (AMH), gonadotropins and ovarian steroids in PCOS patients compared to normally ovulating and menstruating women. By comparing the pattern of co-variation between AMH and Luteinizing Hormone, two compounds closely linked to hyperandrogenism and anovulation in PCOS, the involvement of the Hypothalamic-Pituitary-Ovarian axis in PCOS pathology could be elucidated.

Patients

Eight normal-weighted young, anovulatory PCOS-women as study group and ten normal menstruating and ovulating women as controls.

Interventions

Observational prospective study of the circadian variation in AMH, gonadotropins, sex steroids and androgens in a study and a control group. A circadian profile was performed in each study and control subject during a 24-h period by blood sampling every second hour, starting at 8:00 a.m. and continuing until 8:00 a.m. the following day.

Result(s)

Significant differences in hormonal levels were found between the groups, with higher concentrations of AMH, LH and androgens in the PCOS group and lower amounts of FSH and progesterone. A distinct difference in the circadian variation pattern of AMH and LH between PCOS patients and normal controls was seen, with PCOS patients presenting a uniform pattern in serum levels of AMH and LH throughout the study period, without significant nadir late-night values as was seen in the control group. In PCOS women, a significant positive association between LH/ FSH and testosterone was found opposite to controls.

Main outcome measures

Circadian variation in Anti-Müllerian Hormone, gonadotropins and ovarian steroids and the covariation between them.

Conclusion

A significant difference in the circadian secretion of LH and AMH in PCOS women compared to normally ovulating women indicate an increased GnRH pulse, creating high and constant LH serum concentrations. A significant co-variation between LH and AMH may suggest LH as a factor involved in the control of AMH secretion.

Insulin resistance and the polycystic ovary syndrome revisited: an update on mechanisms and implications

Polycystic ovary syndrome (PCOS) is now recognized as an important metabolic as well as reproductive disorder conferring substantially increased risk for type 2 diabetes. Affected women have marked insulin resistance, independent of obesity. This article summarizes the state of the science since we last reviewed the field in the Endocrine Reviews in 1997. There is general agreement that obese women with PCOS are insulin resistant, but some groups of lean affected women may have normal insulin sensitivity. There is a post-binding defect in receptor signaling likely due to increased receptor and insulin receptor substrate-1 serine phosphorylation that selectively affects metabolic but not mitogenic pathways in classic insulin target tissues and in the ovary. Constitutive activation of serine kinases in the MAPK-ERK pathway may contribute to resistance to insulin's metabolic actions in skeletal muscle. Insulin functions as a co-gonadotropin through its cognate receptor to modulate ovarian steroidogenesis. Genetic disruption of insulin signaling in the brain has indicated that this pathway is important for ovulation and body weight regulation. These insights have been directly translated into a novel therapy for PCOS with insulin-sensitizing drugs. Furthermore, androgens contribute to insulin resistance in PCOS. PCOS may also have developmental origins due to androgen exposure at critical periods or to intrauterine growth restriction. PCOS is a complex genetic disease, and first-degree relatives have reproductive and metabolic phenotypes. Several PCOS genetic susceptibility loci have been mapped and replicated. Some of the same susceptibility genes contribute to disease risk in Chinese and European PCOS populations, suggesting that PCOS is an ancient trait.

Cortisol and the polycystic ovary syndrome

Adrenal steroidogenesis is under the control of the hypothalamic-pituitary-adrenal (HPA) axis. Furthermore, metabolic factors including insulin and obesity-related signals may play a role in the regulation of both enzymes involved in the steroidogenetic pathways, as well as in the regulation of the HPA axis. In women with the polycystic ovary syndrome (PCOS), cortisol production rate is probably normal, although adrenal androgens can be overproduced in a subset of affected women. Cortisol metabolism and regeneration from inactive glucocorticoids can also be disrupted in PCOS, thereby contributing to determining an adrenal hyperandrogenic state. Finally, overactivity of the HPA axis may be related to the high prevalence of psychopathological and eating disorders in women with PCOS, implying a maladaptive allostatic load in the adaptive mechanisms to chronic stress exposure.

Reproductive tissues maintain insulin sensitivity in diet-induced obesity

Reproductive dysfunction is associated with obesity. We previously showed that female mice with diet-induced obesity (DIO) exhibit infertility and thus serve as a model of human polycystic ovary syndrome (PCOS). We postulated that differential insulin signaling of tissues leads to reproductive dysfunction; therefore, a comparison of insulin signaling in reproductive tissues and energy storage tissues was performed. Pituitary-specific insulin receptor knockout mice were used as controls. High-fat diet-induced stress, which leads to insulin resistance, was also investigated by assaying macrophage infiltration and phosphorylated Jun NH(2)-terminal kinase (pJNK) signaling. In lean mice, reproductive tissues exhibited reduced sensitivity to insulin compared with peripheral metabolic tissues. However, in obese mice, where metabolic tissues exhibited insulin resistance, the pituitary and ovary maintained insulin sensitivity. Pituitaries responded to insulin through insulin receptor substrate (IRS)2 but not IRS1, whereas in the ovary, both IRS1 and IRS2 were activated by insulin. Macrophage infiltration and pJNK signaling were not increased in the pituitary or ovary of lean mice relative to DIO mice. The lack of inflammation and cytokine signaling in the pituitary and ovary in DIO mice compared with lean mice may be one of the reasons that these tissues remained insulin sensitive. Retained sensitivity of the pituitary and ovary to insulin may contribute to the pathophysiology of PCOS.

The lack of association between polycystic ovary syndrome and metabolic syndrome: Iranian PCOS prevalence study

OBJECTIVE

This study was designed to evaluate the prevalence of the metabolic syndrome (MetS) and insulin resistance (IR) in a large population-based study in Iran.

RESEARCH DESIGN AND METHODS

Anthropometric measurements, biochemical parameters and IR were compared between 136 polycystic ovary syndrome (PCOS) subjects and 423 healthy controls recruited from among 1126 reproductive aged women (18-45 year). PCOS and MetS were diagnosed using the Rotterdam criteria and Joint Interim Statement, respectively. IR was defined using the homeostatic model assessment-IR).

RESULTS

Among the PCOS subjects, the mean ± SD age, body mass index (BMI) and waist circumference were 31 ± 7·7 years, 26·4 ± 5·8 kg/m(2) and 84 ± 13·3 cm, respectively; corresponding values among healthy controls were 36 ± 7·5 years, 26·4 ± 5·0 kg/m(2) and 85 ± 11·9 cm, respectively. Age and BMI adjusted prevalences of MetS in PCOS subjects and controls were 18·5% (CI 95%, 15·3-21·7%) and 18·3% (CI 95%, 15·1-21·5%), respectively [P = not significant (NS)]. Age and BMI adjusted prevalences of IR in PCOS and healthy controls were 27·2% (CI 95%, 23·5-30·9%) and 24·2% (CI 95%, 20·6-27·8%), respectively (P < 0·01).

CONCLUSIONS

Metabolic syndrome was no more frequent in a representative sample of PCOS Iranian population than in healthy controls. However, the prevalence of IR in PCOS appears to be higher than in controls. It seems that the association between PCOS and MetS needs more consideration.

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.

Evidence that obesity and androgens have independent and opposing effects on gonadotropin production from puberty to maturity

Optimal fat mass is necessary for normal gonadotropin levels in adults, and both undernutrition and overnutrition suppress gonadotropins: thus, the gonadotropin response to relative adipose mass is biphasic. Adult obesity is associated with blunted luteinizing hormone (LH) pulse amplitude that is partially attributable to increased LH clearance rate. Testosterone appears to have a biphasic effect on gonadotropin production in females. Moderate elevations of testosterone appear to stimulate LH production at both the hypothalamic and pituitary level, while very high levels of testosterone suppress LH. Thus, obesity per se appears to suppress gonadotropin production, and moderate hyperandrogenemia in women appears to stimulate LH. The ordinary hypergonadotropic hyperandrogenism of obese women appears to be an exception to this model because it is usually due to polycystic ovary syndrome (PCOS), a condition in which intrinsic functional ovarian hyperandrogenism and excess adiposity share a common origin that involves insulin-resistant hyperinsulinemia. LH elevation seems to be secondary to hyperandrogenemia and is absent in the most obese cases. Overweight early pubertal girls have significant blunting of sleep-related LH production, which is the first hormonal change of puberty. The data are compatible with the possibility that excess adiposity may paradoxically subtly suppress hypothalamic-pituitary-gonadal function in early puberty although it is known to contribute to the early onset of puberty.

Rescue of obesity-induced infertility in female mice due to a pituitary-specific knockout of the insulin receptor

Obesity is associated with insulin resistance in metabolic tissues such as adipose, liver, and muscle, but it is unclear whether nonclassical target tissues, such as those of the reproductive axis, are also insulin resistant. To determine if the reproductive axis maintains insulin sensitivity in obesity in vivo, murine models of diet-induced obesity (DIO) with and without intact insulin signaling in pituitary gonadotrophs were created. Diet-induced obese wild-type female mice (WT DIO) were infertile and experienced a robust increase in luteinizing hormone (LH) after gonadotropin-releasing hormone (GnRH) or insulin stimulation. By contrast, both lean and obese mice with a pituitary-specific knockout of the insulin receptor (PitIRKO) exhibited reproductive competency, indicating that insulin signaling in the pituitary is required for the reproductive impairment seen in DIO and that the gonadotroph maintains insulin sensitivity in a setting of peripheral insulin resistance.

Insulin augments gonadotropin-releasing hormone induction of translation in LbetaT2 cells

The integrated signaling of insulin and gonadotropin-releasing hormone in the pituitary gonadotropes may have a profound bearing on reproductive function, although the cross-receptor signaling mechanisms are unclear. We demonstrate that the insulin receptor is constitutively localized to non-caveolar lipid raft microdomains in the pituitary gonadotrope cell line LbetaT2. The localization to rafts is consistent with similar localization of the GnRH receptor. Insulin receptor phosphorylation occurs in raft domains and activates the downstream signaling targets Insulin Receptor Substrate1 and Akt/Protein Kinase B. Although insulin alone does not strongly activate the extracellular signal-regulated kinase second messenger cascade, co-stimulation potentiates the phosphorylation of the extracellular signal-regulated kinase by gonadotropin-releasing hormone. The co-stimulatory effect of insulin and gonadotropin-releasing hormone is also evident in increased activation of cap-dependent translation. In contrast, co-stimulation attenuates Akt/Protein Kinase B activation. Our results show that both gonadotropin-releasing hormone and insulin are capable of mutually altering their respective regulatory signaling cascades. We suggest that this provides a mechanism to integrate neuropeptide and energy homeostatic signals to modulate reproductive function.

The role of the endogenous opioid system in polycystic ovary syndrome

OBJECTIVE

To review the complex role of the opioid system in reproduction and carbohydrate metabolism, abnormalities in the opioid system in women with polycystic ovary syndrome (PCOS), and the role of opioid antagonists in the management of PCOS-related infertility.

DESIGN

Pertinent articles were identified through a computer PubMed search. References of selected articles were hand searched for additional citations.

CONCLUSION(S)

Endogenous opioids are generally considered inhibitory central neurotransmitters. Peripherally, opioids are involved in the regulation of pancreatic islet function, hepatic insulin clearance, and glucose metabolism, potentially contributing to the pathogenesis of hyperinsulinemia and insulin resistance in PCOS. The presence of sex steroids is required for normal function of the opioid system in both GnRH secretion and carbohydrate metabolism. In women with PCOS, growing evidence suggests dysregulation of the opioid system both centrally and peripherally, with complex interactions. The opioid system effects on carbohydrate metabolism appear to be modulated by obesity. Finally, naltrexone has been demonstrated to successfully augment traditional ovulation induction regimens, but has limited support as a single ovulation induction agent for PCOS.

Blunted sleep-related luteinizing hormone rise in healthy premenarcheal pubertal girls with elevated body mass index

OBJECTIVE

Our objective was to determine whether excessive adiposity is associated with alteration of the normal hormonal changes of early pubertal girls.

DESIGN AND PARTICIPANTS

Healthy 6.4- to 9.5-yr-old, prepubertal (PRE, n = 20) and 9.4- to 13.0-yr-old pubertal premenarcheal volunteers (PUB, n = 20) were divided into excessive-weight (EW) or normal-weight (NW) groups according to the 85th percentile body mass index. INTERVENTIONS AND SETTING: Overnight blood sampling; GnRH agonist (GnRHag), low-dose ACTH, oral glucose tolerance tests, and pelvic ultrasonograms were performed in our Clinical Research Center.

RESULTS

EW girls were similar in age and baseline and ACTH- and GnRHag-stimulated androgen levels to stage-matched NW girls. However, the sleep-related LH rise was blunted in EW-PUB girls compared with NW-PUB girls. The sleep-related rise of mean LH in EW-PUB [0.68 +/- 0.35 (sem) U/liter] was insignificant, less than that of NW-PUB (2.1 +/- 0.45, P < 0.05) and not significantly different from that of PRE girls (0.08+/-0.03). EW-PUB had slower LH pulse frequency and a lower rise in LH pulse amplitude during sleep than NW-PUB girls (both P < 0.05). Overnight FSH patterns paralleled LH patterns, whereas estradiol levels were similar in stage-matched NW and EW groups, differing between stages as expected. Early morning and peak LH, FSH, and estradiol responses to GnRHag were similar in EW-PUB and NW-PUB and significantly greater than those of PRE girls.

CONCLUSIONS

Healthy EW-PUB girls have significantly blunted sleep-related LH production. These data suggest that excess adiposity, in the absence of sex steroid excess, may subtly suppress hypothalamic-pituitary-gonadal function in premenarcheal pubertal girls.

Sex differences in obesity and the regulation of energy homeostasis

Obesity prevalence is generally higher in women than in men, and there is also a sex difference in body fat distribution. Sex differences in obesity can be explained in part by the influence of gonadal steroids on body composition and appetite; however, behavioural, socio-cultural and chromosomal factors may also play a role. This review, which evolved from the 2008 Stock Conference on sex differences in obesity, summarizes current research and recommendations related to hormonal and neuroendocrine influences on energy balance and fat distribution. A number of important gaps in the research are identified, including a need for more studies on chromosomal sex effects on energy balance, the role of socio-cultural (i.e. gender) factors in obesity and the potential deleterious effects of high-fat diets during pregnancy on the foetus. Furthermore, there is a paucity of clinical trials examining sex-specific approaches and outcomes of obesity treatment (lifestyle-based or pharmacological), and research is urgently needed to determine whether current weight loss programmes, largely developed and tested on women, are appropriate for men. Last, it is important that both animal and clinical research on obesity be designed and analysed in such a way that data can be separately examined in both men and women.

Metabolic and hormonal changes induced by pioglitazone in polycystic ovary syndrome: a randomized, placebo-controlled clinical trial

CONTEXT

Polycystic ovary syndrome (PCOS) is characterized by insulin resistance, compensatory hyperinsulinemia, increased prevalence of impaired glucose tolerance, and increased ovarian androgen biosynthesis.

OBJECTIVE

The aim of the study was to evaluate effects of pioglitazone on whole body insulin action and ovarian androgen biosynthesis in PCOS.

DESIGN

We performed a randomized placebo-controlled trial.

SETTING

The study was conducted at the Special Diagnostic and Treatment Unit of the Veterans Affairs Medical Center, San Diego, and the University of California, San Diego, General Clinical Research Center.

PATIENTS OR OTHER PARTICIPANTS

A total of 23 subjects with PCOS were evaluated at baseline and end of treatment. Six age- and body mass index-matched women without PCOS were normal controls for baseline evaluation.

INTERVENTION

Subjects with PCOS were randomized to oral placebo or pioglitazone 45 mg daily for 6 months.

MAIN OUTCOME MEASURE(S)

The primary outcome measures were whole body insulin action as measured by hyperinsulinemic euglycemic clamp and ovarian androgen biosynthesis as measured by leuprolide-stimulated production of 17-hydroxyprogesterone (17-OHP).

RESULTS

Compared with placebo, pioglitazone treatment significantly improved multiple measures of insulin action, including glucose disposal rate (P < 0.01), 2-h glucose during 75-g oral glucose tolerance test (P < 0.01), area under the curve glucose during oral glucose tolerance test (P < 0.01), serum adiponectin (P < 0.01), and fasting hyperinsulinemia (P < 0.01). Compared to placebo, pioglitazone treatment reduced the increment of leuprolide-stimulated 17-OHP (P < 0.02). Improvements in glucose disposal rate correlated with reductions in 17-OHP stimulation (P < 0.02).

CONCLUSIONS

Compared to placebo, pioglitazone treatment in PCOS was associated with improvements in insulin action and glucose homeostasis and ameliorated the hyperandrogenic ovarian response.