Estrogen negative feedback on gonadotropin secretion: evidence for a direct pituitary effect in women

Reproductive toxicity of PFOA, PFOS and their substitutes: A review based on epidemiological and toxicological evidence

Per- and polyfluoroalkyl substances (PFAS) have already drawn a lot of attention for their accumulation and reproductive toxicity in organisms. Perfluorooctanoic acid (PFOA) and perfluorooctanoic sulfonate (PFOS), two representative PFAS, are toxic to humans and animals. Due to their widespread use in environmental media with multiple toxicities, PFOA and PFOS have been banned in numerous countries, and many substitutes have been produced to meet market requirements. Unfortunately, most alternatives to PFOA and PFOS have proven to be cumulative and highly toxic. Of the reported multiple organ toxicities, reproductive toxicity deserves special attention. It has been confirmed through epidemiological studies that PFOS and PFOA are not only associated with reduced testosterone levels in humans, but also with an association with damage to the integrity of the blood testicular barrier. In addition, for women, PFOA and PFOS are correlated with abnormal sex hormone levels, and increase the risk of infertility and abnormal menstrual cycle. Nevertheless, there is controversial evidence on the epidemiological relationship that exists between PFOA and PFOS as well as sperm quality and reproductive hormones, while the evidence from animal studies is relatively consistent. Based on the published papers, the potential toxicity mechanisms for PFOA, PFOS and their substitutes were reviewed. For males, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Apoptosis and autophagy in spermatogenic cells; (2) Apoptosis and differentiation disorders of Leydig cells; (3) Oxidative stress in sperm and disturbance of Ca2+ channels in sperm membrane; (4) Degradation of delicate intercellular junctions between Sertoli cells; (5) Activation of brain nuclei and shift of hypothalamic metabolome. For females, PFOA and PFOS may produce reproductive toxicity in the following five ways: (1) Damage to oocytes through oxidative stress; (2) Inhibition of corpus luteum function; (3) Inhibition of steroid hormone synthesis; (4) Damage to follicles by affecting gap junction intercellular communication (GJIC); (5) Inhibition of placental function. Besides, PFAS substitutes show similar reproductive toxicity with PFOA and PFOS, and are even more toxic to the placenta. Finally, based on the existing knowledge, future developments and direction of efforts in this field are suggested.

Peak serum luteinising hormone cut-off during gonadotropin-releasing hormone analogue test for diagnosing central precocious puberty was lower in girls with obesity as compared with girls with normal weight

OBJECTIVE

Serum luteinising hormone (LH) concentration has been reported to be lower in girls with overweight and obesity (OW/OB) as compared with girls with normal weight (NW). This study aimed to evaluate peak serum LH concentration during gonadotropin-releasing hormone analogue (GnRHa) test in girls with OW/OB and NW who had central precocious puberty (CPP) and to determine peak serum LH cut-off for diagnosing CPP in girls with OW/OB.

DESIGN, PATIENTS AND MEASUREMENTS

Medical records of 971 girls with premature breast development who underwent subcutaneous GnRHa (100 µg of triptorelin acetate) test were reviewed. All girls were classified as either CPP or premature thelarche. All of them were further classified into two groups according to their body mass index as NW and OW/OB groups for each Tanner stage.

RESULTS

There were 634 and 337 girls in NW and OW/OB groups, respectively. CPP was diagnosed in 600 girls (249 had Tanner stage II and 351 had Tanner stage III). There were no differences in peak serum LH concentrations between CPP girls with NW and OW/OB. Peak serum LH cut-off of 5 IU/L (the current widely used cut-off) had a sensitivity and a specificity of 75% and 90%, respectively in NW group. Peak serum LH cut-off for CPP diagnosis was lower at 4 IU/L in the OW/OB group with greater sensitivity and specificity of 86% and 93%, respectively. The results were reproducible for each Tanner stage of breasts.

CONCLUSION

Lower peak serum LH cut-off to 4 IU/L for diagnosing CPP in girls with OW/OB should be considered to avoid underdiagnosis of the condition.

46,XX aromatase deficiency: A single-center experience with the varied spectrum and recurrent variants, and a systematic review of hormonal parameters

BACKGROUND

Aromatase deficiency is a rare disorder, with only a few cases reported in India. We describe a single-center experience in western India, with a systematic review of genetically proven 46,XX aromatase deficiency patients to evaluate hormonal parameters.

METHODS

Retrospective review of case records, collating phenotypic and genotypic data and molecular modeling. Systematic review of 46,XX aromatase deficiency, analyzing data on gonadotropins, estrogen and androgens.

RESULTS

In the seven patients from our center, presentation was frequent in childhood or adolescence (4/7: delayed puberty or hyperandrogenism), with maternal virilization (4/7), predominance of Prader III/IV (5/7), and initial rearing as females (6/7). Three patients had hypoplastic ovaries. One patient had spontaneous regular menses. We report three novel (p.Arg115Pro, p.Arg192Pro, and c.145+1_145+4delins) and two recurrent variants (p.Val370Met, and c.145+1_145+4delins) in western and northern India, respectively. On systematic review (n=43), gonadotropins were elevated (FSH>LH) across ages (except preterm infants), androgens were elevated in about one-third of cases during childhood and puberty, and estradiol was lower than in controls in mini-puberty and puberty. Spontaneous thelarche and streak ovaries were significantly more frequent in patients with non-truncating and truncating variants, respectively.

CONCLUSION

We report uncommon presentations with possible founder variants, and highlight hormonal parameters across ages. Serum FSH levels were elevated except in preterms, and can be used as a diagnostic marker.

Physiological and Pharmacological overview of the Gonadotropin Releasing Hormone

Gonadotropin-releasing Hormone (GnRH) is a decapeptide responsible for the control of the reproductive functions. It shows C- and N-terminal aminoacid modifications and two other distinct isoforms have been so far identified. The biological effects of GnRH are mediated by binding to high-affinity G-protein couple receptors (GnRHR), showing characteristic very short C tail. In mammals, including humans, GnRH-producing neurons originate in the embryonic nasal compartment and during early embryogenesis they undergo rapid migration towards the hypothalamus; the increasing knowledge of such mechanisms improved diagnostic and therapeutic approaches to infertility. The pharmacological use of GnRH, or its synthetic peptide and non-peptide agonists or antagonists, provides a valid tool for reproductive disorders and assisted reproduction technology (ART). The presence of GnRHR in several organs and tissues indicates additional functions of the peptide. The identification of a GnRH/GnRHR system in the human endometrium, ovary, and prostate has extended the functions of the peptide to the physiology and tumor transformation of such tissues. Likely, the activity of a GnRH/GnRHR system at the level of the hippocampus, as well as its decreased expression in mice brain aging, raised interest in its possible involvement in neurogenesis and neuronal functions. In conclusion, GnRH/GnRHR appears to be a fascinating biological system that exerts several possibly integrated pleiotropic actions in the complex control of reproductive functions, tumor growth, neurogenesis, and neuroprotection. This review aims to provide an overview of the physiology of GnRH and the pharmacological applications of its synthetic analogs in the management of reproductive and non-reproductive diseases.

Follicle-stimulating hormone is associated with low bone mass in postmenopausal women

We evaluated the influence of two endogenous hormones on bone health in older women. Higher FSH was associated with bone disease, especially in lower estradiol environments. FSH attenuated the relationship between estradiol and bone. This may provide a mechanism through which future clinical research intervenes on bone loss.

INTRODUCTION/PURPOSE

Despite preclinical evidence for an inverse association of follicle-stimulating hormone (FSH) and bone mineral density (BMD), no large epidemiologic studies have evaluated the separate and joint influences of FSH and estradiol on bone in postmenopausal women.

METHODS

In a cross-sectional study of 675 postmenopausal women, we evaluated associations of serum FSH and dual X-ray absorptiometry (DXA)-classified areal BMD as well as low bone mass or osteoporosis (T-score <  - 1.0) of the femoral neck and total hip. We stratified this analysis by serum estradiol (cut at the median). We tested whether FSH mediates the association of estradiol and BMD using the Sobel test.

RESULTS

In linear regression models, there was a significant inverse association of serum FSH with both femoral neck and total hip BMD (both p < 0.01) when adjusted for age, hormone therapy (HT) use, and diabetes. In fully adjusted logistic regression models, women in the highest FSH tertile had higher odds of low bone mass/osteoporosis at the femoral neck (OR = 2.98; 95% CI = 1.86-4.77) and at the total hip (OR = 1.74; 95% CI = 1.06-2.84) compared to those in the lowest FSH tertile. We report evidence of effect modification by estradiol in stratified models and an interaction term. FSH met all criteria of a mediator, including an estimated 70% attenuation of the estradiol-BMD relationship (Sobel p value < 0.001).

CONCLUSIONS

FSH is associated with higher odds of having low bone mass/osteoporosis even after accounting for HT use. FSH is a mediator of the relationship between estradiol and BMD in healthy postmenopausal women. Larger, prospective studies of FSH concentrations and bone health are needed.

Adaptation of the Porcine Pituitary Transcriptome, Spliceosome and Editome during Early Pregnancy

The physiological mechanisms of the porcine reproduction are relatively well-known. However, transcriptomic changes and the mechanisms accompanying transcription and translation processes in various reproductive organs, as well as their dependence on hormonal status, are still poorly understood. The aim of this study was to gain a principal understanding of alterations within the transcriptome, spliceosome and editome occurring in the pituitary of the domestic pig (Sus scrofa domestica L.), which controls basic physiological processes in the reproductive system. In this investigation, we performed extensive analyses of data obtained by high-throughput sequencing of RNA from the gilts' pituitary anterior lobes during embryo implantation and the mid-luteal phase of the estrous cycle. During analyses, we obtained detailed information on expression changes of 147 genes and 43 long noncoding RNAs, observed 784 alternative splicing events and also found the occurrence of 8729 allele-specific expression sites and 122 RNA editing events. The expression profiles of the selected 16 phenomena were confirmed by PCR or qPCR techniques. As a final result of functional meta-analysis, we acquired knowledge regarding intracellular pathways that induce changes in the processes accompanying transcription and translation regulation, which may induce modifications in the secretory activity of the porcine adenohypophyseal cells.

Antioxidant, Anti-Inflammatory, Anti-Menopausal, and Anti-Cancer Effects of Lignans and Their Metabolites

Since chronic inflammation can be seen in severe, long-lasting diseases such as cancer, there is a high demand for effective methods to modulate inflammatory responses. Among many therapeutic candidates, lignans, absorbed from various plant sources, represent a type of phytoestrogen classified into secoisolariciresionol (Seco), pinoresinol (Pino), matairesinol (Mat), medioresinol (Med), sesamin (Ses), syringaresinol (Syr), and lariciresinol (Lari). Lignans consumed by humans can be further modified into END or ENL by the activities of gut microbiota. Lignans are known to exert antioxidant and anti-inflammatory activities, together with activity in estrogen receptor-dependent pathways. Lignans may have therapeutic potential for postmenopausal symptoms, including cardiovascular disease, osteoporosis, and psychological disorders. Moreover, the antitumor efficacy of lignans has been demonstrated in various cancer cell lines, including hormone-dependent breast cancer and prostate cancer, as well as colorectal cancer. Interestingly, the molecular mechanisms of lignans in these diseases involve the inhibition of inflammatory signals, including the nuclear factor (NF)-κB pathway. Therefore, we summarize the recent in vitro and in vivo studies evaluating the biological effects of various lignans, focusing on their values as effective anti-inflammatory agents.

Luteal phase support for women trying to conceive by intrauterine insemination or sexual intercourse

BACKGROUND

Ovulation induction may impact endometrial receptivity due to insufficient progesterone secretion. Low progesterone is associated with poor pregnancy outcomes.

OBJECTIVES

To assess the effectiveness and safety of luteal phase support (LPS) in infertile women trying to conceive by intrauterine insemination or by sexual intercourse.

SEARCH METHODS

We searched the Cochrane Gynaecology and Fertility Group Specialised Register, CENTRAL, MEDLINE, Embase, PsycINFO, LILACS, trial registries for ongoing trials, and reference lists of articles (from inception to 25 August 2021).

SELECTION CRITERIA

Randomised controlled trials (RCTs) of LPS using progestogen, human chorionic gonadotropin (hCG), or gonadotropin-releasing hormone (GnRH) agonist supplementation in IUI or natural cycle.

DATA COLLECTION AND ANALYSIS

We used standard methodological procedures expected by Cochrane. Our primary outcomes were live birth rate/ongoing pregnancy rate (LBR/OPR) and miscarriage.  MAIN RESULTS: We included 25 RCTs (5111 participants). Most studies were at unclear or high risk of bias. We graded the certainty of evidence as very low to low. The main limitations of the evidence were poor reporting and imprecision. 1. Progesterone supplement versus placebo or no treatment  We are uncertain if vaginal progesterone increases LBR/OPR (risk ratio (RR) 1.10, 95% confidence interval (CI) 0.81 to 1.48; 7 RCTs; 1792 participants; low-certainty evidence) or decreases miscarriage per pregnancy compared to placebo or no treatment (RR 0.70, 95% CI 0.40 to 1.25; 5 RCTs; 261 participants). There were no data on LBR or miscarriage with oral stimulation. We are uncertain if progesterone increases LBR/OPR in women with gonadotropin stimulation (RR 1.24, 95% CI 0.80 to 1.92; 4 RCTs; 1054 participants; low-certainty evidence) and oral stimulation (clomiphene citrate or letrozole) (RR 0.97, 95% CI 0.58 to 1.64; 2 RCTs; 485 participants; low-certainty evidence). One study reported on OPR in women with gonadotropin plus oral stimulation; the evidence from this study was uncertain (RR 0.73, 95% CI 0.37 to 1.42; 1 RCT; 253 participants; low-certainty evidence). Given the low certainty of the evidence, it is unclear if progesterone reduces miscarriage per clinical pregnancy in any stimulation protocol (RR 0.68, 95% CI 0.24 to 1.91; 2 RCTs; 102 participants, with gonadotropin; RR 0.67, 95% CI 0.30 to 1.50; 2 RCTs; 123 participants, with gonadotropin plus oral stimulation; and RR 0.53, 95% CI 0.25 to 1.14; 2 RCTs; 119 participants, with oral stimulation). Low-certainty evidence suggests that progesterone in all types of ovarian stimulation may increase clinical pregnancy compared to placebo (RR 1.38, 95% CI 1.10 to 1.74; 7 RCTs; 1437 participants, with gonadotropin; RR 1.40, 95% CI 1.03 to 1.90; 4 RCTs; 733 participants, with gonadotropin plus oral stimulation (clomiphene citrate or letrozole); and RR 1.44, 95% CI 1.04 to 1.98; 6 RCTs; 1073 participants, with oral stimulation). 2. Progesterone supplementation regimen  We are uncertain if there is any difference between 300 mg and 600 mg of vaginal progesterone for OPR and multiple pregnancy (RR 1.58, 95% CI 0.81 to 3.09; 1 RCT; 200 participants; very low-certainty evidence; and RR 0.50, 95% CI 0.05 to 5.43; 1 RCT; 200 participants, very low-certainty evidence, respectively). No other outcomes were reported for this comparison. There were three different comparisons between progesterone regimens. For OPR, the evidence is very uncertain for intramuscular (IM) versus vaginal progesterone (RR 0.59, 95% CI 0.34 to 1.02; 1 RCT; 225 participants; very low-certainty evidence); we are uncertain if there is any difference between oral and vaginal progesterone (RR 1.25, 95% CI 0.70 to 2.22; 1 RCT; 150 participants; very low-certainty evidence) or between subcutaneous and vaginal progesterone (RR 1.05, 95% CI 0.54 to 2.05; 1 RCT; 246 participants; very low-certainty evidence). We are uncertain if IM or oral progesterone reduces miscarriage per clinical pregnancy compared to vaginal progesterone (RR 0.75, 95% CI 0.43 to 1.32; 1 RCT; 81 participants and RR 0.58, 95% CI 0.11 to 3.09; 1 RCT; 41 participants, respectively). Clinical pregnancy and multiple pregnancy were reported for all comparisons; the evidence for these outcomes was very uncertain. Only one RCT reported adverse effects. We are uncertain if IM route increases the risk of adverse effects when compared with the vaginal route (RR 9.25, 95% CI 2.21 to 38.78; 1 RCT; 225 participants; very low-certainty evidence). 3. GnRH agonist versus placebo or no treatment  No trials reported live birth. The evidence is very uncertain about the effect of GnRH agonist in ongoing pregnancy (RR 1.10, 95% CI 0.70 to 1.74; 1 RCT; 291 participants, very low-certainty evidence), miscarriage per clinical pregnancy (RR 0.73, 95% CI 0.26 to 2.10; 2 RCTs; 79 participants, very low-certainty evidence) and clinical pregnancy (RR 1.00, 95% CI 0.68 to 1.47; 2 RCTs; 340 participants; very low-certainty evidence), and multiple pregnancy (RR 0.28, 95% CI 0.11 to 0.70; 2 RCTs; 126 participants). 4. GnRH agonist versus vaginal progesterone  The evidence for the effect of GnRH agonist injection on clinical pregnancy is very uncertain (RR 1.00, 95% CI 0.51 to 1.95; 1 RCT; 242 participants). 5. HCG injection versus no treatment  The evidence for the effect of hCG injection on clinical pregnancy (RR 0.93, 95% CI 0.40 to 2.13; 1 RCT; 130 participants) and multiple pregnancy rates (RR 1.03, 95% CI 0.22 to 4.92; 1 RCT; 130 participants) is very uncertain. 6. Luteal support in natural cycle No study evaluated the effect of LPS in natural cycle. We could not perform sensitivity analyses, as there were no studies at low risk of selection bias and not at high risk in other domains.

AUTHORS' CONCLUSIONS

We are uncertain if vaginal progesterone supplementation during luteal phase is associated with a higher live birth/ongoing pregnancy rate. Vaginal progesterone may increase clinical pregnancy rate; however, its effect on miscarriage rate and multiple pregnancy rate is uncertain. We are uncertain if IM progesterone improves ongoing pregnancy rates or decreases miscarriage rate when compared to vaginal progesterone. Regarding the other reported comparisons, neither oral progesterone nor any other medication appears to be associated with an improvement in pregnancy outcomes (very low-certainty evidence).

Clinicoradiologic diagnosis of a rare type of congenital adrenal hyperplasia: A case report from Nepal

Congenital adrenal hyperplasia includes defects in the synthesis of steroid hormones in the adrenal cortex. The implications of this disorder manifest in other genitourinary organs, including ovaries and uterus. The diagnosis may be suspected based on the clinical and radiologic features.

Hormonal regulation of ovarian follicle growth in humans: Model-based exploration of cycle variability and parameter sensitivities

We present a modelling and simulation framework for the dynamics of ovarian follicles and key hormones along the hypothalamic-pituitary-gonadal axis throughout consecutive human menstrual cycles. All simulation results (hormone concentrations and ovarian follicle sizes) are in biological units and can easily be compared to clinical data. The model takes into account variability in follicles' response to stimulating hormones, which introduces variability between cycles. The growth of ovarian follicles in waves is an emergent property in our model simulations and further supports the hypothesis that follicular waves are also present in humans. We use Approximate Bayesian Computation and cluster analysis to construct a population of virtual subjects and to study parameter distributions and sensitivities. The model can be used to compare and optimize treatment protocols for ovarian hyperstimulation, thus potentially forming the integral part of a clinical decision support system in reproductive endocrinology.

Relationship between metabolic syndrome and follicle-stimulating hormone in postmenopausal women

Depletion of ovarian reserve during menopausal transition raises follicle-stimulating hormone (FSH) markedly and menopause is related to an increased risk for metabolic syndrome (MetS). This study examined the relationship between FSH and MetS in postmenopausal women.We evaluated the anthropometric values, lipid profiles, high-sensitivity C-reactive protein (hs-CRP) level, Homeostasis model assessment for insulin resistance (HOMA-IR), and serum adipokines levels in 219 postmenopausal women. Serum FSH and estradiol levels were significantly lower in the MetS group than in the non-MetS group. An inverse correlation was observed between FSH with body fat mass (BFM), and HOMA-IR, and a positive correlation was found between FSH and adiponectin level after adjustment for age, years since menopause, BMI, and serum estradiol.The odds ratio for MetS was higher significantly in the lowest quartile of FSH level than the highest quartile of FSH level (odd ratio = 1.32, 95% CI = 1.09-1.75). Our study showed an increased FSH level favored insulin sensitivity with a higher adiponectin and lower HOMA-IR as well as a lower incidence of MetS in postmenopausal women.These findings suggest a new approach to the role of FSH for regulating energy metabolism and for use as a biomarker of MetS risk in postmenopausal women.This systematic review is based on published researches, so there is no ethical approval required.

Biochemical Characterization and Molecular Determination of Estrogen Receptor-α (ESR1 PvuII-rs2234693 T>C) and MiRNA-146a (rs2910164 C>G) Polymorphic Gene Variations and Their Association with the Risk of Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is regarded as one of the most frequently encountered endocrine disorders and affects millions of young women worldwide, resulting in an array of complex metabolic alterations and reproductive failure. PCOS is a risk factor for diabetes mellitus, obstructive sleep apnea, obesity and depression in patients. Estrogen receptors (ESRs) are significant candidates in endocrine function and ovarian response in women. Moreover, microRNAs and long non-coding RNAs are emerging as principal mediators of gene expression and epigenetic pathways in various disease states. This study has characterized the clinical parameters in PCOS patients with comprehensive biochemical profiling compared to healthy controls and further examined the influence of allelic variations for estrogen receptor-α (ESR1 PvuII-rs2234693 T>C) and miRNA-146a (rs2910164 C>G) gene polymorphism on the risk of and susceptibility to PCOS. In this case-control study, we have used amplification refractory mutation specific (ARMS)-PCR to detect and determine the presence of these polymorphic variants in the study subjects. Our results demonstrated that most of the biochemical markers, which were analyzed in the study, show statistically significant alterations in PCOS patients, including fasting glucose, free insulin, HOMA-IR, LDL, HDL, cholesterol and hormones such as FSH, LH, testosterone and progesterone, which correlate with the established biochemical alterations in the disorder. Further, it is reported that for estrogen receptor-α (ESR1 PvuII-rs2234693 T>C), the frequency of the T allele (fT) was significantly higher among patients (0.64 vs. 0.44) compared to controls, while the frequency of the C allele (fC) was lower in patients (0.36 vs. 0.56) compared to controls. However, it was found that there was no association of an increased risk of PCOS with the ESR1 PvuII-rs2234693 C>T gene polymorphism. On the contrary, the study found strong association of miRNA-146a (rs2910164 C>G) gene polymorphism with an enhanced risk of PCOS. The frequency of the C allele (fC) was significantly higher among patients (0.52 vs. 0.36) compared to controls. The frequency of the G allele (fG) was found to be lower in patients (0.48 vs. 0.64) compared to controls. The codominant, dominant and recessive models display a statistically significant association of polymorphic variations with PCOS. Moreover, the G allele was associated strongly with PCOS susceptibility with an OR = 1.92 (95%) CI = (1.300−2.859), RR = 1.38 (1.130−1.691) p-value < 0.001.

Inositols in the ovaries: activities and potential therapeutic applications

INTRODUCTION

Myo-inositol (MI) and d-chiro-inositol (DCI) play a key role in ovarian physiology, as they are second messengers of insulin and gonadotropins. Ex-vivo and in-vitro experiments demonstrate that both isomers are deeply involved in steroid biosynthesis, and that reduced MI-to-DCI ratios are associated with pathological imbalance of sex hormones.

AREAS COVERED

This expert opinion provides an overview of the physiological distribution of MI and DCI in the ovarian tissues, and a thorough insight of their involvement into ovarian steroidogenesis. Insulin resistance and compensatory hyperinsulinemia dramatically reduce the MI-to-DCI ratio in the ovaries, leading to gynecological disorders characterized by hyperandrogenism, altered menstrual cycle and infertility.

EXPERT OPINION

Available evidence indicates that MI and DCI have very specific physiological roles and, seemingly, physiological MI-to-DCI ratios in the ovaries are crucial to maintain the correct homeostasis of steroids. Inositol treatments should be evaluated on the patients' specific conditions and needs, as long-term supplementation of high doses of DCI may cause detrimental effects on the ovarian functionality. In addition, the effects of inositol therapy on the different PCOS phenotypes should be further investigated in order to better tailor the supplementation.

Congenital disorders of estrogen biosynthesis and action

Estrogens regulate pubertal development and reproductive function in women, spermatogenesis in men, and bone turnover and metabolic conditions in individuals of both sexes. Estradiol, the major estrogen in humans, is synthesized from testosterone by the action of aromatase and exerts its effects though binding to estrogen receptors. Germline loss- and gain-of-function variants in CYP19A1, the gene encoding aromatase, lead to aromatase deficiency and aromatase excess syndrome, respectively. Germline loss-of-function variants in ESR1, the gene encoding estrogen receptor α, are known to cause of estrogen insensitivity/resistance. In addition, rare variants in ESR1 and ESR2 have been implicated in various disease phenotypes. Clinical studies on these rare endocrine disorders provided clues to understand the biological functions of estrogens in the human body. This review introduces the genetic basis, phenotypes, and current management procedures of congenital disorders in estrogen biosynthesis and action.

Triphenyl phosphate delayed pubertal timing and induced decline of ovarian reserve in mice as an estrogen receptor antagonist

Although concerns have been raised about the adverse effects of triphenyl phosphate (TPhP) on female fertility, its risk to ovarian functioning remains unknown. In this study, female C57BL/6 mice at postnatal day 21 were exposed on a daily basis to TPhP dose of 2, 10, and 50 mg/kg for 40 days. A significant delay in pubertal timing was observed in the mice exposed to 50 mg/kg of TPhP. An estrogen-responsive reporter transgenic mice assay demonstrated that TPhP significantly downregulated the estrogen receptor (ER) signaling by 45.1% in the whole body in the 50 mg/kg group, and by 14.7-43.7% in the uterus for all exposure groups compared with the control. This strong antagonistic activity of TPhP toward ER explained the delay in pubertal timing. A significant reduction in the number of follicles in all stages was observed in mice after being exposed to TPhP for 40 days at concentrations of 10 and 50 mg/kg, resulting in a decline of the ovarian reserve. The elevation of the follicle-stimulating hormone concentration may have contributed to this phenomenon, as controlled by the antagonistic activity of TPhP toward ER in the brain. The toxic effects of TPhP on ovarian functioning highlight this chemical as a potential risk factor for female fertility.

Inositols: From Established Knowledge to Novel Approaches

Myo-inositol (myo-Ins) and D-chiro-inositol (D-chiro-Ins) are natural compounds involved in many biological pathways. Since the discovery of their involvement in endocrine signal transduction, myo-Ins and D-chiro-Ins supplementation has contributed to clinical approaches in ameliorating many gynecological and endocrinological diseases. Currently both myo-Ins and D-chiro-Ins are well-tolerated, effective alternative candidates to the classical insulin sensitizers, and are useful treatments in preventing and treating metabolic and reproductive disorders such as polycystic ovary syndrome (PCOS), gestational diabetes mellitus (GDM), and male fertility disturbances, like sperm abnormalities. Moreover, besides metabolic activity, myo-Ins and D-chiro-Ins deeply influence steroidogenesis, regulating the pools of androgens and estrogens, likely in opposite ways. Given the complexity of inositol-related mechanisms of action, many of their beneficial effects are still under scrutiny. Therefore, continuing research aims to discover new emerging roles and mechanisms that can allow clinicians to tailor inositol therapy and to use it in other medical areas, hitherto unexplored. The present paper outlines the established evidence on inositols and updates on recent research, namely concerning D-chiro-Ins involvement into steroidogenesis. In particular, D-chiro-Ins mediates insulin-induced testosterone biosynthesis from ovarian thecal cells and directly affects synthesis of estrogens by modulating the expression of the aromatase enzyme. Ovaries, as well as other organs and tissues, are characterized by a specific ratio of myo-Ins to D-chiro-Ins, which ensures their healthy state and proper functionality. Altered inositol ratios may account for pathological conditions, causing an imbalance in sex hormones. Such situations usually occur in association with medical conditions, such as PCOS, or as a consequence of some pharmacological treatments. Based on the physiological role of inositols and the pathological implications of altered myo-Ins to D-chiro-Ins ratios, inositol therapy may be designed with two different aims: (1) restoring the inositol physiological ratio; (2) altering the ratio in a controlled way to achieve specific effects.

Interplay of KNDy and nNOS neurons: A new possible mechanism of GnRH secretion in the adult brain

Reproduction in mammals is favoured when there is sufficient energy available to permit the survival of offspring. Neuronal nitric oxide synthase expressing neurons produce nitric oxide in the proximity of the gonadotropin-releasing hormone neurons in the preoptic region. nNOS neurons are an integral part of the neuronal network controlling ovarian cyclicity and ovulation. Nitric oxide can directly regulate the activity of the GnRH neurons and play a vital role neuroendocrine axis. Kisspeptin neurons are essential for the GnRH pulse and surge generation. The anteroventral periventricular nucleus (AVPV), kisspeptin neurons are essential for GnRH surge generation. KNDy neurons are present in the hypothalamus's arcuate nucleus (ARC), co-express NKB and dynorphin, essential for GnRH pulse generation. Kisspeptin-neurokinin B-dynorphin (KNDy) neuroendocrine molecules of the hypothalamus are key components in the central control of GnRH secretion. The hypothalamic neurons kisspeptin, KNDy, nitric oxide synthase (NOS), and other mediators such as leptin, adiponectin, and ghrelin, play an active role in attaining puberty. Kisspeptin signalling is mediated by NOS, which further results in the secretion of GnRH. Neuronal nitric oxide is critical for attaining puberty, but its direct role in adult GnRH secretion is poorly understood. This review mainly focuses on the role of nNOS and its interplay with KNDy neurons in the hormonal regulation of reproduction.

Associations of PCBS, dioxins and furans with follicle-stimulating hormone and luteinizing hormone in postmenopausal women: National Health and Nutrition Examination Survey 1999-2002

BACKGROUND

The general population is exposed to the group of endocrine disrupting chemicals persistent organic pollutants (POPs), that includes polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

OBJECTIVES

The aim of this research was to evaluate the associations of serum levels of PCB, PCDD, and PCDF congeners with follicle stimulating hormone (FSH) and luteinizing hormone (LH) in postmenopausal women not taking exogenous hormones. We hypothesized that associations of POPs with these gonadotropins could be modified by factors affecting endogenous hormones.

METHODS

Cross-sectional analyses were conducted on data from 89 postmenopausal women using data from the National Health and Nutrition Examination Survey (NHANES). POPs were summarized based on classification schemes thought to reflect toxicological properties. Associations of POPs and gonadotropin hormones were modeled with multivariable regression models. When evidence of interaction was found, conditional effects were estimated.

RESULTS

We found inverse associations of LH, but not FSH, with exposure to anti-estrogenic and/or dioxin-like POPs, but not with non dioxin-like PCBs. A doubling of dioxin-like toxic equivalents (TEQs) was associated with a decrease in LH of 11.9% (95% CI = -21.3%, -1.4%, p = 0.03). Inverse associations were enhanced by potential effect modifiers related to both direct and indirect estrogenicity, including obesity and the obesity-related condition inflammation.

CONCLUSIONS

These investigations support a pattern of endocrine-disrupting effects by dioxin-like POPs among postmenopausal women, especially those with conditions related to peripheral estrogenicity.

A Novel Hypothesis: A Role for Follicle Stimulating Hormone in Abdominal Aortic Aneurysm Development in Postmenopausal Women

An abdominal aortic aneurysm (AAA) is a dilatation of the abdominal aorta, which can potentially be fatal due to exsanguination following rupture. Although AAA is less prevalent in women, women with AAA have a more severe AAA progression compared to men as reflected by enhanced aneurysm growth rates and a higher rupture risk. Women are diagnosed with AAA at an older age than men, and in line with increased osteoporosis and cardiovascular events, the delayed AAA onset has been attributed to the reduction of the protective effect of oestrogens during the menopausal transition. However, new insights have shown that a high follicle stimulating hormone (FSH) level during menopause may also play a key role in those diseases. In this report we hypothesize that FSH may aggravate AAA development and progression in postmenopausal women via a direct and/or indirect role, promoting aorta pathology. Since FSH receptors (FSHR) are reported on many other cell types than granulosa cells in the ovaries, it is feasible that FSH stimulation of FSHR-bearing cells such as aortic endothelial cells or inflammatory cells, could promote AAA formation directly. Indirectly, AAA progression may be influenced by an FSH-mediated increase in osteoporosis, which is associated with aortic calcification. Also, an FSH-mediated decrease in cholesterol uptake by the liver and an increase in cholesterol biosynthesis will increase the cholesterol level in the circulation, and subsequently promote aortic atherosclerosis and inflammation. Lastly, FSH-induced adipogenesis may lead to obesity-mediated dysfunction of the microvasculature of the aorta and/or modulation of the periaortic adipose tissue. Thus the long term increased plasma FSH levels during the menopausal transition may contribute to enhanced AAA disease in menopausal women and could be a potential novel target for treatment to lower AAA-related events in women.

TGFBR3L-An Uncharacterised Pituitary Specific Membrane Protein Detected in the Gonadotroph Cells in Non-Neoplastic and Tumour Tissue

Simple Summary

Pituitary neuroendocrine tumours originate from the endocrine cells of the anterior pituitary gland and may develop from any of the cell lineages responsible for producing the different pituitary hormones. The details related to tumour differentiation and hormone production in these tumours are not fully understood. The aim of our study was to investigate an uncharacterised pituitary enriched protein, transforming growth factor beta-receptor 3 like (TGFBR3L). The TGFBR3L protein is highly expressed in the pituitary compared to other organs. We found the protein to be gonadotroph-specific, i.e., detected in the cells that express follicle-stimulating and luteinizing hormones (FSH/LH). The gonadotroph-specific nature of TGFBR3L, a correlation to both FSH and LH as well as an inverse correlation to membranous E-cadherin and oestrogen receptor β suggests a role in gonadotroph cell development and function and, possibly, tumour progression.

Abstract

Here, we report the investigation of transforming growth factor beta-receptor 3 like (TGFBR3L), an uncharacterised pituitary specific membrane protein, in non-neoplastic anterior pituitary gland and pituitary neuroendocrine tumours. A polyclonal antibody produced within the Human Protein Atlas project (HPA074356) was used for TGFBR3L staining and combined with SF1 and FSH for a 3-plex fluorescent protocol, providing more details about the cell lineage specificity of TGFBR3L expression. A cohort of 230 pituitary neuroendocrine tumours were analysed. In a subgroup of previously characterised gonadotroph tumours, correlation with expression of FSH/LH, E-cadherin, oestrogen (ER) and somatostatin receptors (SSTR) was explored. TGFBR3L showed membranous immunolabeling and was found to be gonadotroph cell lineage-specific, verified by co-expression with SF1 and FSH/LH staining in both tumour and non-neoplastic anterior pituitary tissues. TGFBR3L immunoreactivity was observed in gonadotroph tumours only and demonstrated intra-tumour heterogeneity with a perivascular location. TGFBR3L immunostaining correlated positively to both FSH (R = 0.290) and LH (R = 0.390) immunostaining, and SSTR3 (R = 0.315). TGFBR3L correlated inversely to membranous E-cadherin staining (R = −0.351) and oestrogen receptor β mRNA (R = −0.274). In conclusion, TGFBR3L is a novel pituitary gland specific protein, located in the membrane of gonadotroph cells in non-neoplastic anterior pituitary gland and in a subset of gonadotroph pituitary tumours.

Estradiol-17β Pharmacokinetics and Histological Assessment of the Ovaries and Uterine Horns following Intramuscular Administration of Estradiol Cypionate in Feral Cats

Simple Summary

Feral cats (Felis catus) have a devastating impact on Australian native fauna. Several programs exist to control their numbers through lethal removal, using tools such as baiting with toxins. Adult male cats are especially difficult to control. We hypothesized that one way to capture these male cats is to lure them using female cats. As female cats are seasonal breeders, a method is needed to artificially induce reproductive (estrous) behavior so that they could be used for this purpose year-round (i.e., regardless of season). Estrogens can be given to cats to induce estrous behavior, but it is not known for how long this elevates the blood concentrations of estradiol. Following the administration of a long-acting estrogen, estradiol cypionate, to nine captive feral cats, blood estrogen concentrations remained elevated for several days. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats.

Abstract

The control of feral cats (Felis catus) in Australia is a key biological conservation issue. Male cats are more difficult to control than female cats. Collared and tagged female cats displaying estrous behavior have been considered as a way to lure male cats and reveal their locations. As female cats are seasonal breeders, artificial induction of estrous behavior following the administration of a long-acting estrogen could improve their use for this purpose. Estradiol cypionate was intramuscularly administered to nine entire non-pregnant female feral cats, of unknown estrous status, at 0.1, 0.3, or 0.5 mg/kg. Mean peak serum concentrations of estradiol-17β were 365 pg/mL (0.1 mg/kg), 1281 pg/mL (0.3 mg/kg), and 1447 pg/mL (0.5 mg/kg). The time-course of estradiol-17β concentrations after various doses of estradiol cypionate was assessed using non-compartmental and non-linear mixed-effects methods. At the highest-studied dose (0.5 mg/kg), the 50th percentile of estradiol-17β concentrations exceeded 0.1 ng/mL for 11.8 days, and 0.05 ng/mL for 14.6 days. The duration increased with increasing dose. No signs of toxicity were noticed in any cat during the study. This information will be useful to ongoing studies that are investigating ways to reduce the abundance of feral cats in Australia, especially adult male cats.

FSH Levels Are Related to E-cadherin Expression and Subcellular Location in Nonfunctioning Pituitary Tumors

CONTEXT

Gonadotroph pituitary neuroendocrine tumors (PitNETs) can express follicle-stimulating hormone (FSH) and luteinizing hormone (LH) or be hormone negative, but they rarely secrete hormones. During tumor development, epithelial cells develop a mesenchymal phenotype. This process is characterized by decreased membranous E-cadherin and translocation of E-cadherin to the nucleus. Estrogen receptors (ERs) regulate both E-cadherin and FSH expression and secretion. Whether the hormone status of patients with gonadotroph PitNETs is regulated by epithelial-to-mesenchymal transition (EMT) and ERs is unknown.

OBJECTIVES

To study the effect of EMT on hormone expression in gonadotroph nonfunctioning (NF)-PitNETs.

DESIGN

Molecular and clinical analyses of 105 gonadotroph PitNETs. Immunohistochemical studies and real-time quantitative polymerase chain reaction were performed for FSH, LH, E-cadherin, and ERα. Further analyses included blood samples, clinical data, and radiological images.

SETTING

All patients were operated on in the same tertiary referral center.

RESULTS

NF-PitNET with high FSH expression had decreased immunohistochemical staining for membranous E-cadherin (P < .0001) and increased staining for nuclear E-cadherin (P < .0001). Furthermore, high FSH expression was associated with increased ERα staining (P = .0002) and ERα mRNA (P = .0039). Circulating levels of plasma-FSH (P-FSH) correlated with FSH staining in gonadotroph NF-PitNET (P = .0025). Tumor size and invasiveness was not related to FSH staining, E-cadherin, or ERα. LH expression was not associated with E-cadherin or ERα.

CONCLUSION

In gonadotroph PitNETs, FSH staining is related to E-cadherin, ERα expression, and circulating levels of P-FSH. There was no association between FSH staining and invasiveness. The clinical significance of these findings will be investigated in ongoing prospective studies.

New clinical targets of d-chiro-inositol: rationale and potential applications

INTRODUCTION

Inositols have a key role in ovarian physiology and the literature reports a wealth of studies about the major isomer, myo-inositol (MI). However, information about d-chiro-inositol (DCI) is still scarce, despite the ratio MI:DCI is tissue-specific and actively maintained by an insulin-dependent epimerase enzyme.

AREAS COVERED

This expert opinion provides an overview of the physiological contribution of DCI in regulating steroidogenesis. DCI indeed mediates the intracellular signaling of insulin, which induces the biosynthesis of androgens. Studies on second messengers of insulin also revealed that DCI has a specific role in modulating the activity of aromatase enzyme. Specifically, recent findings demonstrated that DCI influences the enzyme gene expression, thus reducing the conversion of androgens into estrogens.

EXPERT OPINION

Available evidence suggests that the effects of DCI administration may be similar to those of aromatase inhibitors, but without causing hypo-estrogenic states. Therefore, DCI treatments should be evaluated for either estrogen-dependent gynecological conditions or low testosterone states in male subjects.

IDEA Group Consensus Statement on Medical Management of Adult Gender Incongruent Individuals Seeking Gender Reaffirmation as Female

Cross sex hormone therapy (CSHT) is a strongly desired medical intervention for gender incongruent individuals. The goal is to change secondary sex characteristics to facilitate gender presentation that is consistent with the desired sex. When appropriately prescribed CSHT can greatly improve mental health and quality of life for gender incongruent individuals. Appropriate care for gender incongruent individuals in India is almost absent due to lack of country specific guideline and lack of training amongst the medical professionals. This document is intended to assist endocrinologists and physicians whose adult gender incongruent client is seeking gender reaffirmation as female (transfeminine). These individuals require a safe and effective CSHT regimen that will suppress endogenous male hormone secretion and maintain physiologic levels of female sex hormone. In this document, we offer suggestions based on an in-depth review of Guidelines of Endocrine Society, The World Professional Association for Transgender Health guidelines, the Sappho Good Practice Guide of India and collegial meetings with expert Indian clinicians working in this field. Clinicians represented in our expert panel are not gender specialists by training but have developed expertise due to the volume of gender incongruent individuals they manage. This consensus statement on medical management provides protocols for the prescribing clinician relating to diagnosis, baseline evaluation and counselling, prescription planning for feminizing hormone therapy and anti-androgen therapy, targets for monitoring hormone therapy, choice of therapy, clinical and biochemical monitoring, recommending sex reaffirmation surgery and peri-operative hormone therapy. The recommendations made in this document should not be perceived as a rigid set of guidelines and the treating clinicians are encouraged to modify our suggested protocols to address emerging issues.

Post-photostimulation energy intake accelerated pubertal development in broiler breeder pullets

The effect of ME intake (MEI) on the reproductive system was evaluated. Ross 308 broiler breeder pullets (n = 140) were assigned to 2 treatments from 22 to 26 wk of age: (1) Low-energy diet fed restricted (2,807 kcal/kg, low MEI) and (2) high-energy diet fed unrestricted (3,109 kcal/kg, high MEI). Daylength was increased from 8 to 14 h at 22 wk of age with a light intensity of 30 lux. Daily palpation was used to detect sexual maturity via the presence of a hard-shelled egg in the shell gland. Expression of gonadotropin releasing hormone-I (GnRH) and gonadotropin inhibitory hormone (GnIH) genes in the hypothalamus and GnRH receptor (GnRH-RI) and GnIH receptor (GnIH-R) genes in the anterior pituitary gland of each pullet was evaluated from 22 to 26 wk of age using quantitative real time-PCR. Blood samples were taken weekly and luteinizing hormone (LH), follicle stimulating-hormone (FSH), and 17-beta-estradiol (E2) determined using commercial ELISA kits. Carcass samples were used for determination of CP and fat content. Data were analyzed using the MIXED procedure in SAS, and differences were reported where P ≤ 0.05. High MEI treatment pullets had 2.3-fold higher GnRH and 1.8-fold higher GnRH-RI mRNA levels than low MEI pullets. MEI affected neither expression of GnIH and GnIH-R nor carcass protein content. For high MEI (489 kcal/D) and low MEI treatments (258 kcal/D), respectively, from 22 to 26 wk of age (P ≤ 0.05), LH concentration was 3.05 and 1.60 ng/mL; FSH concentration was 145 and 89.3 pg/mL; E2 concentration was 429 and 266 pg/mL, and carcass lipid was 13.9 and 10.3%. The onset of lay for pullets in the high MEI treatment advanced such that 100% had laid by 26 wk of age compared with 30% in the low MEI treatment. We concluded that higher MEI advanced the activation of the hypothalamic–pituitary–gonadal axis and also increased body lipid deposition, and moreover, stimulated reproductive hormone levels which overall accelerated puberty in broiler breeder pullets.

The effect of methadone on the hypothalamic pituitary gonadal axis and sexual function: A systematic review

BACKGROUND

Opioid abuse is a public health crisis. As opioid misuse worsens, efforts are being made to increase access to medication-assisted treatments. Methadone is a medication-assisted treatment used to treat opioid dependence and chronic pain. While methadone is beneficial in the treatment of opiate abuse and chronic pain, side effects of the medication include hormonal and sexual function changes. The purpose of this report is to review the effects of methadone on the hypothalamic pituitary gonadal axis hormones and sexual functioning in males and females.

METHODS

A search of PubMed was conducted using pre-defined criteria, resulting in the evaluation of 295 articles. A total of 72 articles, including 52 human studies and 20 animal studies, met the selection criteria and were reviewed. The included studies examined the effects of methadone on the hypothalamic pituitary gonadal axis and/or sexual function.

RESULTS

There was evidence of methadone-induced hormonal changes, disruptions in the hypothalamic pituitary gonadal axis, and sexual dysfunction, although there was some variability in the results of the reviewed studies. Differences in methadone dose and length of exposure to treatment appears to influence the variability in the results. Much of the literature examines the effects of methadone in males, with very limited research examining the effects in females.

CONCLUSIONS

Despite its effectiveness for opiate abuse and chronic pain treatment, methadone has disruptive effects on the hypothalamic pituitary gonadal axis and sexual function. Further research is warranted to better define potential methadone-induced endocrine consequences and to further examine the effects of methadone in females.

Does night work affect age at which menopause occurs?

PURPOSE OF REVIEW

To delineate the current state of evidence on the impact of night shift work on age at natural menopause.

RECENT FINDINGS

The only direct evidence is from a single observational study, which indicates that women who work night shifts are at moderately higher risk for earlier menopause and that this risk is more pronounced among younger women. Underlying biological mechanisms have yet to be sufficiently substantiated. A long-held line of inquiry, most strongly propagated by the observed link between night shift work and female breast cancer, is the 'Light at Night' hypothesis, which suggests melatonin-mediated circadian disruption as a potential regulator of reproductive signaling in women. Supporting evidence is found from observations of changes in endogenous melatonin production among night working women or in response to light exposure, and corresponding changes in endogenous ovarian hormone levels and modulated menstrual patterns, among other indications of altered central ovulation-governing processes. Susceptibility to night shift work may be modified by chronotype.

SUMMARY

This review summarizes the literature related to night work and ovulatory regulation in humans, prioritizing population-based evidence to provide motivation for the study of circadian disruption and night shift work as a regulator of menopausal timing.

Pubertal Hormonal Changes and the Autonomic Nervous System: Potential Role in Pediatric Orthostatic Intolerance

Puberty is initiated by hormonal changes in the adolescent body that trigger physical and behavioral changes to reach adult maturation. As these changes occur, some adolescents experience concerning pubertal symptoms that are associated with dysfunction of the autonomic nervous system (ANS). Vasovagal syncope (VVS) and Postural Orthostatic Tachycardia Syndrome (POTS) are common disorders of the ANS associated with puberty that are related to orthostatic intolerance and share similar symptoms. Compared to young males, young females have decreased orthostatic tolerance and a higher incidence of VVS and POTS. As puberty is linked to changes in specific sex and non-sex hormones, and hormonal therapy sometimes improves orthostatic symptoms in female VVS patients, it is possible that pubertal hormones play a role in the increased susceptibility of young females to autonomic dysfunction. The purpose of this paper is to review the key hormonal changes associated with female puberty, their effects on the ANS, and their potential role in predisposing some adolescent females to cardiovascular autonomic dysfunctions such as VVS and POTS. Increases in pubertal hormones such as estrogen, thyroid hormones, growth hormone, insulin, and insulin-like growth factor-1 promote vasodilatation and decrease blood volume. This may be exacerbated by higher levels of progesterone, which suppresses catecholamine secretion and sympathetic outflow. Abnormal heart rate increases in POTS patients may be exacerbated by pubertal increases in leptin, insulin, and thyroid hormones acting to increase sympathetic nervous system activity and/or catecholamine levels. Given the coincidental timing of female pubertal hormone surges and adolescent onset of VVS and POTS in young women, coupled with the known roles of these hormones in modulating cardiovascular homeostasis, it is likely that female pubertal hormones play a role in predisposing females to VVS and POTS during puberty. Further research is necessary to confirm the effects of female pubertal hormones on autonomic function, and their role in pubertal autonomic disorders such as VVS and POTS, in order to inform the treatment and management of these debilitating disorders.

Transcriptome analysis reveals that cyclophosphamide induces premature ovarian failure by blocking cholesterol biosynthesis pathway

AIMS

The present study aimed to investigate the effects of cyclophosphamide (Cytoxan, CTX) on premature ovarian failure (POF) in mice and its regulatory mechanisms by transcriptome analysis.

MAIN METHODS

Female C57BL/6 mice were treated with a single intraperitoneal injection of 70 mg/kg CTX. Serum levels of estradiol (E₂) and follicle stimulating hormone (FSH) were measured by enzyme-linked immunosorbent assay (ELISA), and follicular structure differences were observed by hematoxylin and eosin (H&E) staining. The main mechanism of POF was investigated by RNA-seq data, protein-protein interaction (PPI) networks and qPCR analysis.

KEY FINDINGS

The serum levels of E₂ were significantly decreased and those of FSH were significantly increased compared to the control group. The ovarian weights of the mice in the CTX group were reduced, and abnormal follicular structures were also observed in the CTX group. The RNA-seq data show that the downregulated genes were related to the cholesterol biosynthesis pathway. The PPI network and qPCR analyses further confirm that the PPAR signaling pathway and the ovarian infertility genes were also involved in blocking the cholesterol biosynthesis pathway. The differences were statistically significant.

SIGNIFICANCE

Our results indicate that CTX may exert its anti-tumor effects by inactivating the cholesterol biosynthesis pathway, and simultaneously reducing the supply of estrogen precursor materials, ultimately leading to the occurrence of POF. Our data provided a preliminary theoretical basis for resolving the clinical toxicity and side effects of CTX.

Hypothalamic and pituitary transcriptome profiling using RNA-sequencing in high-yielding and low-yielding laying hens

The reproductive physiology and laying performance of laying hens are regulated by the hypothalamus and pituitary. To understand the mechanism of egg laying regulation, we sequenced and analysed the hypothalamus and pituitary expression profiles in high- and low-yielding laying Chinese Dagu Chickens (CDC) using RNA-seq. More than 46 million clean reads and 24,873 tentative genes were obtained using the Gallus gallus genome as a reference. Transcriptome analysis in hypothalamus and pituitary revealed seven and 39 differentially expressed genes (DEGs) between high- and low-yielding CDC hens, respectively. A total of 24 and 22 DEGs were up-regulated and down-regulated, respectively, and 13 novel genes were identified. Functional annotation and pathway enrichment analysis showed that DEGs in the hypothalamus were mainly enriched in glycosaminoglycan biosynthesis. DEGs significantly enriched in the pituitary primarily affected the extracellular matrix, the protein extracellular matrix, and the extracellular space. Pathways involving phenylalanine metabolism, 2-oxocarboxylic acid metabolism, the glycosphingolipid biosynthesis-ganglion series, and local adhesion were significantly enriched in the pituitary. Eight DEGs, PRDX6, TRIB2, OVCH2, CFD, Peptidase M20, SLC7A10, and two other amino acid transporters, are involved in the metabolism and transport of amino acids. To our knowledge, this is the first study comparing the hypothalamus and pituitary transcriptomes of high- and low-yielding laying hens. Our findings suggest that putative differences in gene expression can provide a base for further research in this field. Moreover, we identified increased expression of genes involved in amino acid metabolism, glycosaminoglycan biosynthesis, and oestrogen negative feedback systems in low-yielding laying hens, highlighting their potential as biomarkers of egg production.

Effects of Song Experience and Song Quality on Immediate Early Gene Expression in Female Canaries (Serinus canaria)

Female songbirds are thought to make mate choices based on aspects of male song quality. Male canaries (Serinus canaria) produce songs with "special" syllables that have been shown to be highly salient to female listeners - eliciting high rates of sexual displays and enhanced immediate early gene (IEG) expression. Immunohistochemistry for the IEG ZENK was used to examine the effects of experience with these syllables on activity in the caudal mesopallium (CMM) and nidocaudal mesopallium (NCM), two auditory areas important in processing conspecific song. Photostimulated female canaries were housed in sound attenuated chambers and played pseudosongs containing either three special syllables or three non-special syllables, an intro, and an outro sequence. Females that heard special syllable pseudosongs exhibited higher ZENK expression in CMM. To assess the effects of experience, photostimulated females were pair housed and exposed to playback of song with or without special syllables for 14 days. After transfer to individual housing, birds were played one of the aforementioned stimuli or silence. ZENK expression in CMM and NCM was equivalent for song with and without special syllables, but significantly lower for silence. Females who experienced song with special syllables had lower plasma estradiol concentrations after final song playback. This study indicates that CMM exhibits an IEG response bias to special syllables in limited acoustic contexts, but not in full song, which may contain additional biologically relevant information. Furthermore, estradiol concentrations may mediate changes in song responses, serving as a mechanism for modulating mate choice in differing song environments.

L-lactate induces specific genome wide alterations of gene expression in cultured bovine granulosa cells

Background

Previously, we could show that L-lactate affects cultured bovine granulosa cells (GC) in a specific manner driving the cells into an early pre-ovulatory phenotype. Here we studied genome wide effects in L-lactate-treated GC to further elucidate the underlying mechanisms that are responsible for the L-lactate induced transformation. Cultured estrogen producing GC treated either with L-lactate or vehicle control were subjected to mRNA microarray analysis.

Results

The analysis revealed 487 differentially expressed clusters, representing 461 annotated genes. Of these, 333 (= 318 genes) were identified as up- and 154 (= 143 genes) as down-regulated. As the top up-regulated genes we detected TXNIP, H19 and AHSG as well as our previously established marker transcripts RGS2 and PTX3. The top down-regulated genes included VNN1, SLC27A2 and GFRA1, but also MYC and the GC marker transcript CYP19A1. Pathway analysis with differentially expressed genes indicated “cAMP-mediated signaling” and “Axon guidance signaling” among the most affected pathways. Furthermore, estradiol, progesterone and Vegf were identified as potential upstream regulators. An effector network analysis by IPA provided first hints that processes of “angiogenesis” and “vascularization”, but also “cell movement” appeared to be activated, whereas “organismal death” was predicted to be inhibited.

Conclusions

Our data clearly show that L-lactate alters gene expression in cultured bovine GC in a broad, but obviously specific manner. Pathway analysis revealed that the mode of L-lactate action in GC initiates angiogenic processes, but also migratory events like cell movement and axonal guidance signaling, thus supporting the transformation of GC into an early luteal phenotype.

Electronic supplementary material

The online version of this article (10.1186/s12864-019-5657-6) contains supplementary material, which is available to authorized users.

Dysregulation of hypothalamic-pituitary estrogen receptor α-mediated signaling causes episodic LH secretion and cystic ovary

Polycystic ovary syndrome (PCOS) is a hypothalamic-pituitary-gonadal (HPG) axis disorder. PCOS symptoms most likely result from a disturbance in the complex feedback regulation system of the HPG axis, which involves gonadotrophic hormones and ovarian steroid hormones. However, the nature of this complex and interconnecting feedback regulation makes it difficult to dissect the molecular mechanisms responsible for PCOS phenotypes. Global estrogen receptor α (ERα) knockout (KO) mice exhibit a disruption of the HPG axis, resulting in hormonal dysregulation in which female ERα KO mice have elevated levels of serum estradiol (E2), testosterone, and LH. The ERα KO females are anovulatory and develop cystic hemorrhagic ovaries that are thought to be due to persistently high circulating levels of LH from the pituitary. However, the role of ERα in the pituitary is still controversial because of the varied phenotypes reported in pituitary-specific ERα KO mouse models. Therefore, we developed a mouse model where ERα is reintroduced to be exclusively expressed in the pituitary on the background of a global ERα-null (PitERtgKO) mouse. Serum E2 and LH levels were normalized in PitERtgKO females and were comparable to wild-type serum levels. However, the ovaries of PitERtgKO adult mice displayed a more overt cystic and hemorrhagic phenotype when compared with ERα KO littermates. We determined that anomalous sporadic LH secretion caused the severe ovarian phenotype of PitERtgKO females. Our observations suggest that pituitary ERα is involved in the estrogen negative feedback regulation, whereas hypothalamic ERα is necessary for the precise control of LH secretion. Uncontrolled, irregular LH secretion may be the root cause of the cystic ovarian phenotype with similarities to PCOS.-Arao, Y., Hamilton, K. J., Wu, S.-P., Tsai, M.-J., DeMayo, F. J., Korach, K. S. Dysregulation of hypothalamic-pituitary estrogen receptor α-mediated signaling causes episodic LH secretion and cystic ovary.

Detection of the effects and potential interactions of FSH, VEGFA, and 2-methoxyestradiol in follicular angiogenesis, growth, and atresia in mouse ovaries

Ovarian follicular development is a complex process that requires codevelopment of the perifollicular vascular network, which is closely regulated by angiogenic factors, gonadotropins, sex steroids, and their metabolites. To detect the effects of vascular endothelial growth factor 120 (VEGF120), follicle-stimulating hormone (FSH), and 2-methoxyestradiol (2ME2) on follicular angiogenesis during development and atresia, we treated sexually immature and mature female mice with VEGF120, FSH, 2ME2, and FSH receptor (FSHR) antagonist singly or in combination via intraperitoneal injection. The number of follicles and their perifollicular angiogenesis and atresia rates at different developmental stages were examined in paraffin sections after hematoxylin and eosin staining. The results showed that the exogenous factors have specific and precise effects on developmental, angiogenesis, and atresia processes in follicles of different sizes in mature and immature mice. Perifollicular angiogenesis was regulated by VEGFA and closely related to follicular development and atresia. 2ME2 affected angiogenesis through VEGFA and might regulate atresia directly. FSH might control VEGFA function via both transcriptional and posttranscriptional mechanisms because FSHR was required for achieving VEGFA functions at all the follicular development stages. The present study presents insights into the mechanisms of FSH, 2ME2, and VEGFA in follicular development and disorders and provides a foundation for the development of new therapeutic strategies.

Dysregulation of Kisspeptin and Leptin, as Anorexigenic Agents, Plays Role in the Development of Obesity in Postmenopausal Women

During the menopausal period, women have a higher tendency to develop obesity and any other metabolic syndromes. Dysregulation of leptin and kisspeptin signaling as anorexigenic agents is believed to be the connection between metabolic disorders and altered reproductive function. Therefore, this study aimed at investigating the association between leptin, soluble leptin receptor (sOBR), free leptin index, kisspeptin concentrations, and body mass index (BMI) in postmenopausal women. A cross-sectional study was carried out among 171 postmenopausal women aged 40-75 years from 2017 to 2018. Subjects were assigned into 2 groups according to their BMIs: obese group (84 subjects) and nonobese group (87 subjects). In addition to anthropometric measurement, blood sample was collected from each subject for leptin, sOBR, free leptin index (FLI), and kisspeptin evaluation. Bivariate and correlation analysis discovered that leptin and FLI were positively correlated with BMI, while sOBR and kisspeptin were negatively correlated with BMI. Among those variables, multivariate analysis found that leptin, sOBR, and kisspeptin were independently associated with obesity. Therefore, it can be concluded that higher serum leptin concentration and FLI, as well as lower serum sOBR and kisspeptin concentrations, are significantly associated with obesity in postmenopausal women.

Sex Differences in Aging and Associated Biomarkers

Aging is a natural process defined by the gradual, time-dependent decline of biological and behavioural functions, for which individuals of the same chronological age show variability. The capacity of biological systems to continuously adjust for optimal functioning despite ever changing environments is essential for healthy aging, and variability in these adaptive homeostatic mechanisms may reflect such heterogeneity in the aging process. With an ever-increasing aging population, interest in biomarkers of aging is growing. Although no universally accepted definition of biomarkers of healthy aging exists, mediators of homeostasis are consistently used as measures of the aging process. As important sex differences are known to underlie many of these systems, it is imperative to consider that this may reflect, to some extent, the sex differences observed in aging and age-related disease states. This chapter aims to outline sex differences in key homeostatic domains thought to be associated with the pathophysiology of aging, often proposed as biomarkers of aging and age-related disease states. This includes considering sex-based differences and hormonal status with regards to the gonadal and adrenal endocrine systems and immune function.

Gonadotropins and Their Analogs: Current and Potential Clinical Applications

The gonadotropin receptors LH receptor and FSH receptor play a central role in governing reproductive competency/fertility. Gonadotropin hormone analogs have been used clinically for decades in assisted reproductive therapies and in the treatment of various infertility disorders. Though these treatments are effective, the clinical protocols demand multiple injections, and the hormone preparations can lack uniformity and stability. The past two decades have seen a drive to develop chimeric and modified peptide analogs with more desirable pharmacokinetic profiles, with some displaying clinical efficacy, such as corifollitropin alfa, which is now in clinical use. More recently, low-molecular-weight, orally active molecules with activity at gonadotropin receptors have been developed. Some have excellent characteristics in animals and in human studies but have not reached the market-largely as a result of acquisitions by large pharma. Nonetheless, such molecules have the potential to mitigate risks currently associated with gonadotropin-based fertility treatments, such as ovarian hyperstimulation syndrome and the demands of injection-based therapies. There is also scope for novel use beyond the current remit of gonadotropin analogs in fertility treatments, including application as novel contraceptives; in the treatment of polycystic ovary syndrome; in the restoration of function to inactivating mutations of gonadotropin receptors; in the treatment of ovarian and prostate cancers; and in the prevention of bone loss and weight gain in postmenopausal women. Here we review the properties and clinical application of current gonadotropin preparations and their analogs, as well as the development of novel orally active, small-molecule nonpeptide analogs.

Inhibition of catalase activity with 3-amino-1,2,4-triazole intensifies bisphenol A (BPA)-induced toxicity in granulosa cells of female albino rats

Exposure to bisphenol A (BPA), an endocrine disruptor and environmental toxicant, is associated with adverse estrogenic effects in both humans and wildlife species. Because the effects of BPA on the ovary at the cellular level are incompletely understood, the present study was designed to investigate the underlying mechanism of granulosa cell injury following BPA exposure. Eight-week-old female Wistar rats were treated with BPA (25 mg/kg BW/day for 9 days, intraperitonially) with or without pretreatment of the catalase-specific blocker 3-amino-1,2,4-triazole (ATZ; 1 g/kg BW/day for 5 days, intraperitonially). Different oxidative and antioxidant stress parameters, pro-inflammatory cytokines, and hormonal levels were measured. Catalase expression in isolated granulosa cells was analyzed by Western blot. There were noticeable increases in both nitric oxide and lipid peroxidation levels in the granulosa cells of the BPA-treated group with or without pretreatment with ATZ. Compared with the controls, BPA exposure resulted in a significant increase in pro-inflammatory cytokine levels that was further increased following pretreatment with ATZ. Results of the hormonal assays clearly showed a significant decrease in both estrogen and progesterone levels. In contrast, there was a significant increase in both serum follicle-stimulating hormone and luteinizing hormone levels following BPA exposure, with or without ATZ pretreatment. Results of Western blot analysis demonstrated decreased expression of catalase in the BPA-treated group and a further decrease in expression in the group treated with both BPA and ATZ. Our data suggest that catalase plays a role in mediating reproductive damage to granulosa cells exposed to BPA.

Ovarian adult-type granulosa cell tumor: focusing on endocrine-based therapies

Adult-type granulosa cell tumors (GCTs), although rare, are the most commonly diagnosed neoplasms arising in the endocrine-active ovarian stroma. They are characterized by excessive production of estrogens, antimullerian hormone and inhibins. In 2009, a specific mutation in FOXL2 was identified to be pathognomonic of GCTs. How dysregulation of this transcription factor, resulting in upregulation of aromatase, leads to unchecked proliferation, and progression to a malignancy, remains unclear. The key pathological and clinical feature of GCTs that affects their usually favorable outcomes is a diagnosis of greater than Stage 1 disease at presentation. Chemotherapy is given as adjuvant upon an advanced stage diagnosis; however, its effect on survival upon recurrence is modest. On the other hand, aromatase inhibitors also lead to tumor regression and are suitable for long-term maintenance.

Estrogen directly stimulates LHb expression at the pituitary level during puberty in female zebrafish

The LHb expression is up-regulated during puberty in female zebrafish. However, the molecular mechanism underlying how LHb expression is regulated during puberty remains largely unknown. In this study, we found that the mRNA expression levels of lhb, fshb and cyp19a1b were up-regulated along with the puberty onset in zebrafish. Among the three nuclear estrogen receptors (nERs), the esr2b is the only type whose expression is significantly up-regulated during puberty onset in the pituitary. However, in situ hybridization results revealed that lhb mRNA was colocalized with esr1 and esr2a but not esr2b. Exposure to estradiol (E₂) significantly stimulates LHb expression in both wild-type and kiss1^-/-;kiss2^-/-;gnrh3^-/- triple knockout pubertal zebrafish. Moreover, exposure of cultured pituitary cells to E₂ increased the LHb expression, indicating that the estrogenic effect on LHb expression could be acted at the pituitary level. Finally, we cloned and analyzed the promoter of lhb by luciferase assay. Our results indicated that the E₂ responsive regions of lhb promoter for ERα and ERβ2 are identical, suggesting that ERα and ERβ2 could bind to the same half ERE region of the promoter of lhb, exhibiting a classical ERE-dependent pathway. In summary, we demonstrate that E₂ could directly act on the pituitary level to stimulate LHb transcription during puberty in zebrafish.

Local production of neurostradiol affects gonadotropin-releasing hormone (GnRH) secretion at mid-gestation in Lagostomus maximus (Rodentia, Caviomorpha)

Females of the South American plains vizcacha, Lagostomus maximus, show peculiar reproductive features such as massive polyovulation up to 800 oocytes per estrous cycle and an ovulatory process around mid‐gestation arising from the reactivation of the hypothalamic–hypophyseal–ovary (H.H.O.) axis. Estradiol (E₂) regulates gonadotropin‐releasing hormone (GnRH) expression. Biosynthesis of estrogens results from the aromatization of androgens by aromatase, which mainly occurs in the gonads, but has also been described in the hypothalamus. The recently described correlation between GnRH and ERα expression patterns in the hypothalamus of the vizcacha during pregnancy, with coexpression in the same neurons of the medial preoptic area, suggests that hypothalamic synthesis of E₂ may affect GnRH neurons and contribute with systemic E₂ to modulate GnRH delivery during the gestation. To elucidate this hypothesis, hypothalamic expression and the action of aromatase on GnRH release were evaluated in female vizcachas throughout pregnancy. Aromatase and GnRH expression was increased significantly in mid‐pregnant and term‐pregnant vizcachas compared to early‐pregnant and nonpregnant females. In addition, aromatase and GnRH were colocalized in neurons of the medial preoptic area of the hypothalamus throughout gestation. The blockage of the negative feedback of E₂ induced by the inhibition of aromatase resulted in a significant increment of GnRH‐secreted mass by hypothalamic explants. E₂ produced in the same neurons as GnRH may drive intracellular E₂ to higher levels than those obtained from systemic circulation alone. This may trigger for a prompt GnRH availability enabling H.H.O. activity at mid‐gestation with ovulation and formation of accessory corpora lutea with steroidogenic activity that produce the necessary progesterone to maintain gestation to term and guarantee the reproductive success.

Independent relationship between body mass index and LH peak value of GnRH stimulation test in ICPP girls: A cross-sectional study

The effect of obesity on idiopathic central precocious puberty (ICPP) girls is still under discussion. The relationship between body mass index (BMI) and sexual hormone levels of gonadotropin-releasing hormone (GnRH) stimulation test in ICPP girls is controversial and the underlying mechanism is unclear. This study aims to further explore the independent effect of excess adiposity on peak luteinizing hormone (LH) level of stimulation test in ICPP girls and the role of other related factors. A retrospective cross-sectional study was performed on 618 girls diagnosed as having ICPP, including 355 cases of normal weight, 99 cases of overweight and 164 cases of obese. The results showed that obese group had more progressed Tanner stage and no significant difference (P=0.28) in LH peak was found as basal LH value was used as a covariate. The obese group had higher total testosterone (TT), adrenocorticotrophic hormone (ACTH), 17-α hydroxyprogesterone (17-αOHP) and androstendione (AN), with significantly increased fasting insulin (FIN) and homeostasis model of assessment for insulin resistance index (HOMA-IR). Stratified analysis showed inconsistency of the relationship between BMI-standard deviation score (BMI-SDS) and LH peak in different Tanner stages (P for interaction=0.017). Further smoothing plot showed linear and non-linear relationship between BMI-SDS and LH peak in three Tanner stages. Then linear regression model was used to analyze the relationship between BMI-SDS and LH peak in different Tanner stages, with and without different confounding factors being adjusted. In B2 stage, BMI-SDS was negatively associated with LH peak. In B3 stage, when BMI-SDS <1.5, as BMI-SDS increased, the level of LH peak decreased (model I: β=-1.8, 95% CI=-4.7 to 1.1, P=0.214). When BMI-SDS ≥1.5, BMI-SDS was significantly positively associated with LH peak (model I: β=4.5, 95% CI=1.7 to 7.4, P=0.002). In B4 stage, when BMI-SDS <1.5, BMI-SDS was negatively associated with LH peak (model I: β=-11.6, 95% CI=-22.7 to-0.5, P=0.049). When BMI-SDS ≥1.5, BMI-SDS was positively associated with LH peak (model I: β=-4.2, 95% CI=-3.3 to 11.7, P=0.28). It is concluded that there is an independent correlation between BMI-SDS and LH peak of stimulation test in ICPP girls, their relationships are different in different Tanner stages, and the effect of BMI-SDS can be affected by adrenal androgens, estradiol and glucose metabolism parameters.

Metals, hormones and sexual maturation in Flemish adolescents in three cross-sectional studies (2002-2015)

Sex hormone levels and timing of sexual maturation are considered important markers for health status of adolescents in puberty, and previous research suggests they might be influenced by metal exposure. In three campaigns of the Flemish Environment and Health Study (FLEHS I 2002-2006; FLEHS II 2007-2011 and FLEHS III 2012-2015), data were collected on internal exposure to metals (Cd, Cu, Pb, Cr, Mn, Tl, Ni, Sb, Hg, As and As species) and sexual maturation in 2671 14-15years old adolescents. All metals were measured in blood and/or urine, except total- and methylmercury which were measured in hair samples. Sex hormone levels were measured in blood serum of adolescent males of the cohorts of FLEHS I and FLESH II. The use of a uniform methodology in successive campaigns allows to confirm associations between exposure and health in different cohorts and over time. Furthermore, mathematical and statistical density correction methods using creatinine or specific gravity were tested for urinary markers. Significant associations between sex hormones and maturity markers were observed in the FLEHS I and II campaigns, when both were assessed together. Regardless of the applied correction method, creatinine correction systematically introduced bias due to associations of creatinine with sex hormones and maturation markers, especially in adolescent males, while this is not the case for specific gravity. A series of exposure-response associations were found, but several involving Cd, Pb, As, Tl and Cu persisted in different FLEHS campaigns. The effects of Pb and Cu on luteinizing hormone, (free) testosterone, (free) oestradiol and maturation support a xenoestrogenic agonistic action on the feedback of oestradiol to the hypothalamus-pituitary-gonadal axis. Our results suggest that specific care should be taken when selecting urine density correction for investigating associations with hormonal and maturation markers in adolescent males. Furthermore, the possibility of xenoestrogenic effects of certain metals in environmentally exposed adolescents warrants further investigation.

Sequence variations in estrogen receptor 1 and 2 genes and their association with egg production traits in Chinese Dagu chickens

Estrogen receptors α (ESR1) and β (ESR2) play central roles in folliculogenesis and therefore in reproductive biology. In the present study, two single nucleotide polymorphisms (SNPs) were identified in the ESR1 and ESR2 genes using PCR-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing. One of the identified SNPs, a T1101C transition located within exon 4 of the ESR1 gene, was significantly associated with hen-housed egg production (HHEP) at 30, 43, 57 and 66 weeks of age (P<0.05), and egg weight (EW) at 30 weeks (P<0.05). Another SNP, a G1755A transition leading to a non-synonymous substitution (valine 459-to-isoleucine) located within exon 8 of the ESR2 gene, was also markedly correlated with the HHEP at 30, 43, 57 and 66 weeks of age (P<0.05), and EW at 30 weeks (P<0.05). A greater proportion of the additive variance was explained by the SNPs for most of the associated egg production traits (>1%). Furthermore, the results of the combined genotype-based association analysis supported the finding that the two SNPs were associated with the traits under a study. Taken together, our findings suggest that the two sequence variations in the ESR1 and ESR2 genes may provide promising genetic markers for the early selection and prediction of advantageous phenotypes in chicken breeding.

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.