Increased luteinizing hormone and alpha-subunit secretion in women with hyperandrogenic anovulation

Polycystic ovary syndrome (PCOS): progress towards a better understanding and treatment of the syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine and metabolic disorder in women of reproductive age. It has a strong hereditary component estimated at 60 to 70% in daughters. It has been suggested that environmental factors during the fetal period may be involved in the development of the syndrome in adulthood. However, the underlying mechanisms of its transmission remain unknown, thus limiting the development of effective therapeutic strategies.This article highlights how an altered fetal environment (prenatal exposure to high levels of anti-Müllerian hormone) can contribute to the onset of PCOS in adulthood and lead to the transgenerational transmission of neuroendocrine and metabolic traits through alterations in the DNA methylation process.The originality of the translational findings summarized here involves the identification of potential biomarkers for early diagnosis of the syndrome, in addition to the validation of a promising therapeutic avenue in a preclinical model of PCOS, which can improve the management of patients suffering from the syndrome.

Developmental programming: gestational testosterone excess disrupts LH secretion in the female sheep fetus

BACKGROUND

Prenatal testosterone (T) excess results in reproductive and metabolic perturbations in female sheep that closely recapitulate those seen in women with polycystic ovary syndrome (PCOS). At the neuroendocrine level, prenatal T-treated sheep manifest increased pituitary sensitivity to GnRH and subsequent LH hypersecretion. In this study, we investigated the early effects of gestational T-treatment on LH secretion and pituitary function in the female sheep fetus. Additionally, because prenatal T effects can be mediated via the androgen receptor or due to changes in insulin homeostasis, prenatal co-treatment with an androgen antagonist (flutamide) or an insulin sensitizer (rosiglitazone) were tested.

METHODS

Pregnant sheep were treated from gestational day (GD) 30 to 90 with either: 1) vehicle (control); 2) T-propionate (~ 1.2 mg/kg); 3) T-propionate and flutamide (15 mg/kg/day); and 4) T-propionate and rosiglitazone (8 mg/day). At GD 90, LH concentrations were determined in the uterine artery (maternal) and umbilical artery (fetal), and female fetuses were euthanized. Pituitary glands were collected, weighed, and protein level of several key regulators of LH secretion was determined.

RESULTS

Fetal pituitary weight was significantly reduced by prenatal T-treatment. Flutamide completely prevented the reduction in pituitary weight, while rosiglitazone only partially prevented this reduction. Prenatal T markedly reduced fetal LH concentrations and flutamide co-treatment partially restored LH to control levels. Prenatal T resulted in a marked reduction in LH-β protein level, which was associated with a reduction in GnRH receptor and estrogen receptor-α levels and an increase in androgen receptor. With the exception of androgen receptor, flutamide co-treatment completely prevented these alterations in the fetal pituitary, while rosiglitazone largely failed to prevent these changes. Prenatal T-treatment did not alter the protein levels of insulin receptor-β and activation (phosphorylation) of the insulin signaling pathways.

CONCLUSIONS

These findings demonstrate that prenatal T-treatment results in reduced fetal LH secretion, reduced fetal pituitary weight, and altered protein levels of several regulators of gonadotropin secretion. The observations that flutamide co-treatment prevented these changes suggest that programming during fetal development likely occurs via direct androgen actions.

New insights into anti-Müllerian hormone role in the hypothalamic-pituitary-gonadal axis and neuroendocrine development

Research into the physiological actions of anti-Müllerian hormone (AMH) has rapidly expanded from its classical role in male sexual differentiation to the regulation of ovarian function, routine clinical use in reproductive health and potential use as a biomarker in the diagnosis of polycystic ovary syndrome (PCOS). During the past 10 years, the notion that AMH could act exclusively at gonadal levels has undergone another paradigm shift as several exciting studies reported unforeseen AMH actions throughout the Hypothalamic–Pituitary–Gonadal (HPG) axis. In this review, we will focus on these findings reporting novel AMH actions across the HPG axis and we will discuss their potential impact and significance to better understand human reproductive disorders characterized by either developmental alterations of neuroendocrine circuits regulating fertility and/or alterations of their function in adult life. Finally, we will summarize recent preclinical studies suggesting that elevated levels of AMH may potentially be a contributing factor to the central pathophysiology of PCOS and other reproductive diseases.

Developmental Programming: Insulin Sensitizer Prevents the GnRH-Stimulated LH Hypersecretion in a Sheep Model of PCOS

Prenatal testosterone (T) treatment recapitulates the reproductive and metabolic phenotypes of polycystic ovary syndrome in female sheep. At the neuroendocrine level, prenatal T treatment results in disrupted steroid feedback on gonadotropin release, increased pituitary sensitivity to GnRH, and subsequent LH hypersecretion. Because prenatal T-treated sheep manifest functional hyperandrogenism and hyperinsulinemia, gonadal steroids and/or insulin may play a role in programming and/or maintaining these neuroendocrine defects. Here, we investigated the effects of prenatal and postnatal treatments with an androgen antagonist (flutamide [F]) or an insulin sensitizer (rosiglitazone [R]) on GnRH-stimulated LH secretion in prenatal T-treated sheep. As expected, prenatal T treatment increased the pituitary responsiveness to GnRH leading to LH hypersecretion. Neither prenatal interventions nor postnatal F treatment normalized the GnRH-stimulated LH secretion. Conversely, postnatal R treatment completely normalized the GnRH-stimulated LH secretion. At the tissue level, gestational T increased pituitary LHβ, androgen receptor, and insulin receptor-β, whereas it reduced estrogen receptor (ER)α protein levels. Although postnatal F normalized pituitary androgen receptor and insulin receptor-β, it failed to prevent an increase in LHβ expression. Contrarily, postnatal R treatment restored ERα and partially normalized LHβ pituitary levels. Immunohistochemical findings confirmed changes in pituitary ERα expression to be specific to gonadotropes. In conclusion, these findings indicate that increased pituitary responsiveness to GnRH in prenatal T-treated sheep is likely a function of reduced peripheral insulin sensitivity. Moreover, results suggest that restoration of ERα levels in the pituitary may be one mechanism by which R prevents GnRH-stimulated LH hypersecretion in this sheep model of polycystic ovary syndrome-like phenotype.

Interventional studies for polycystic ovarian syndrome in children and adolescents

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

Maturation of luteinizing hormone (gonadotropin-releasing hormone) secretion across puberty: evidence for altered regulation in obese peripubertal girls

CONTEXT

Peripubertal obesity (body mass index-for-age >or= 95%) in girls is associated with hyperandrogenemia. LH likely contributes to this relationship, but overnight LH secretion in obese girls is poorly characterized.

OBJECTIVE

The aim of the study was to evaluate LH pulse characteristics in obese girls throughout pubertal maturation.

DESIGN

We conducted a cross-sectional analysis.

SETTING

The study was performed in a general clinical research center.

PARTICIPANTS

Eight nonobese and five obese Tanner 1-2 girls participated, as well as 32 nonobese and 12 obese Tanner 3-5 girls.

INTERVENTION

Blood samples were collected every 10 min overnight (from 1900 to 0700 h).

MAIN OUTCOME MEASURES

LH pulse frequency, amplitude, and mean LH were measured in three 4-h time blocks (block 1, 1900-2300 h; block 2, 2300-0300 h; and block 3, 0300-0700 h).

RESULTS

Tanner stage 1-2 nonobese girls demonstrated nocturnal increases of LH frequency (P < 0.01, block 1 vs. 2) and mean LH (P < 0.05, block 1 vs. 2 and 3). Obese Tanner 1-2 girls had lower 12-h LH frequency and LH amplitude (P < 0.05 for both), with no overnight changes of LH pulse parameters. Compared to normal, LH frequency was elevated in Tanner 3-5 obese girls (P < 0.01 in all blocks), whereas LH amplitude was low (P < 0.05 in all blocks). Overnight increases of LH amplitude were observed in nonobese Tanner 3-5 girls (P < 0.0001), but not in obese Tanner 3-5 girls.

CONCLUSIONS

Obesity in prepubertal and early pubertal girls is associated with reduced LH secretion and reduced nocturnal changes of LH. In later pubertal girls, obesity is linked with reduced LH amplitude, but elevated LH frequency; the latter may reflect effects of hyperandrogenemia.

Current approaches to the diagnosis and treatment of polycystic ovarian syndrome in youth

Polycystic ovary syndrome (PCOS) is one of the most common endocrinopathies in reproductive-age women. It often presents during late adolescence but in some cases certain features are evident even before menarche. PCOS is a spectrum of disorders with any combination of oligo/anovulation, clinical and/or biochemical evidence of androgen excess, obesity, insulin resistance and polycystic ovaries on ultrasound. The pathogenesis is unknown; however, it is a complex multigenetic disorder where disordered gonadotropin release, dysregulation of steroidogenesis, hyperinsulinism and insulin resistance play a role. The diagnosis is based on a typical physical exam (acne, hirsutism, obesity, and acanthosis nigricans) and laboratory evidence of hyperandrogenism, such as elevated free testosterone, androstenedione and dehydroepiandrosterone sulfate (DHEAS), decreased sex hormone-binding globulin (SHBG) and increased luteinizing hormone (LH). An ovarian ultrasound may detect the multiple cysts. Secondary causes of PCOS need to be excluded. There are several classes of medications correcting different parameters of PCOS that can be used alone or in combination. Oral contraceptive therapy is used to reduce androgen and LH levels with resultant improvement in acne and hirsutism, and the induction of regular menses. Antiandrogens are usually required for a substantial improvement in hirsutism score. Insulin sensitizers such as metformin are a new class of drugs utilized in treatment of PCOS. By improving insulin sensitivity and decreasing insulin levels, they improve the unfavorable metabolic profile of patients with PCOS. Metformin also helps to increase SHBG, decrease androgen levels and induce ovulation. Despite all the available medications, life-style changes are the mainstay of therapy as weight loss and exercise improve all parameters of PCOS without the potential side effects of medication.

Polycystic ovary syndrome in adolescence

Polycystic ovary syndrome (PCOS) is a syndrome of variable combinations of menstrual irregularity, hirsutism or acne, and obesity. It can be diagnosed in adolescence and has early childhood antecedents. PCOS is the single most common endocrine cause of an ovulatory infertility and a major risk factor for the metabolic syndrome and, in turn, development of type 2 diabetes mellitus in women. Thus, it appears that PCOS increases a woman's risk of developing cardiovascular disease. Therefore, identifying girls at risk for PCOS and implementing treatment early in the development of PCOS may be an effective means of preventing some of the long-term complications associated with this syndrome. This article reviews the definition, clinical features, diagnosis, and treatment of PCOS.

The use of a combined regimen of GnRH agonist plus a low-dose oral contraceptive improves the spontaneous pulsatile LH secretory characteristics in patients with polycycstic ovary disease after discontinuation of treatment

PURPOSE

The fertility rate in women with polycystic ovary disease (PCOD) is influenced by the type of treatment received. The present study evaluated the possible correlation between treatment and pulsatile release of gonadotropins.

METHODS

Spontaneous episodic secretion of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) and hormonal parameters were monitored before and after 1, 3, and 6 months after treatments suspension. Twenty-four PCOD patients were randomly divided into two groups of 12 subjects. Group A was treated with gonadotropin-releasing hormone (GnRH)-analogue plus oral contraceptive (OC). Group B was treated only with OC. Both groups were treated for 6 months and followed up for 6 months.

RESULTS

In all subjects the therapeutic regimens reduced the androgenic milieau and the gonadotropin plasma levels. Spontaneous pulsatile secretion of LH and FSH was significantly modified in both groups, but patients who received the combined regimen showed a significantly greater reduction of LH plasma levels and a significantly greater decrease of LH pulse amplitude throughout the 6 months after treatment suspension. Ferriman-Gallway score and ovarian volumes were significantly reduced in patients who received the combined treatment than in the OC-treated patients.

CONCLUSIONS

These data support the evidence of a higher efficacy of the combination of GnRH-a + OC than OC alone in restoring a normal and adequate spontaneous episodic gonadotropin discharge and in decreasing Ferriman-Gallway score and ovarian volumes in patients with PCOD.

Insights into hypothalamic-pituitary dysfunction in polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is characterized by menstrual dysfunction and hyperandrogenism in the absence of other known causes. While the pathogenesis of PCOS remains elusive and is likely to involve abnormalities in several systems, there has long been an association of abnormal gonadotropin secretion with this disorder. In recent studies we have determined that 94% of women meeting the broad criteria for PCOS have an increased LH/FSH ratio. Several lines of evidence suggest that the mechanisms underlying the increased LH/FSH ratio in PCOS include an increased frequency of GnRH secretion. Decreased sensitivity to progesterone negative feedback on the GnRH pulse generator may play a role in this neuroendocrine defect. Additional factors which may contribute to the low to normal FSH levels in the face of increased LH include chronic mild estrogen increases and possibly inhibin. In addition to these effects on the differential control of FSH, there is increased pituitary sensitivity of LH secretion to GnRH. Both estrogen and androgens have been proposed as candidates mediating these effects. Superimposed on these underlying abnormalities in gonadotropin secretion is a marked inhibitory effect of obesity on LH secretion which may be mediated at either a pituitary or hypothalamic level.