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The luteinizing hormone (LH) receptor plays an essential role in male and female gonadal function. Together with the follicle-stimulating hormone (FSH) and thyroid stimulating hormone (TSH) receptors, the LH receptor forms the family of glycoprotein hormone receptors. All glycoprotein hormone receptors share a common modular topography, with an N-terminal extracellular ligand binding domain and a C-terminal seven-transmembrane transduction domain. The ligand binding domain consists of 9 leucine-rich repeats, flanked by N- and C-terminal cysteine-rich regions. Recently, crystal structures have been published of the extracellular domains of the FSH and TSH receptors. However, the C-terminal cysteine-rich region (CCR), also referred to as the "hinge region," was not included in these structures. Both structure and function of the CCR therefore remain unknown. In this study we set out to characterize important domains within the CCR of the LH receptor. First, we mutated all cysteines and combinations of cysteines in the CCR to identify the most probable disulfide bridges. Second, we exchanged large parts of the LH receptor CCR by its FSH receptor counterparts, and characterized the mutant receptors in transiently transfected HEK 293 cells. We zoomed in on important regions by focused exchange and deletion mutagenesis followed by alanine scanning. Mutations in the CCR specifically decreased the potencies of LH and hCG, because the potency of the low molecular weight agonist Org 41841 was unaffected. Using this unbiased approach, we identified Asp330 and Tyr331 as key amino acids in LH/hCG mediated signaling. [ABSTRACT FROM AUTHOR]

The chance of infertile patients conceiving is related to factors like female age and duration of infertility. This prospective observational study evaluated whether the results of ovarian reserve tests, including the novel marker serum anti-Müllerian hormone (AMH), were of additional value in predicting ongoing pregnancy. Two hundred and twenty-two patients diagnosed with unexplained infertility or mild male factor (total motile count > 1O x 106) on the basis of the infertility work-up were prospectively included. Antral follicle count, AMH, inhibin B, FSH and oestradiol concentrations were determined during the early follicular phase. Outcome measures were treatment-dependent and treatment-independent ongoing pregnancy and time to ongoing pregnancy. There were 159 ongoing pregnancies, 52 of which occurred spontaneously. Pregnant patients were significantly younger than those who did not become pregnant (median age 32.4 versus 34.9 years. P < 0.001) and FSH concentrations were higher in non-pregnant patients (median 6.S versus 7.6 lU/l, P = 0.04). Only age (hazard ratio 0.93, 95% CI 0.90-0.97) and whether or not the patient was undergoing treatment (hazard ratio 8.10, 95% CI 5.66-11.61) were significantly associated with time to ongoing pregnancy. Ovarian reserve tests, other than chronological age, seem of limited value in predicting (time to) ongoing pregnancy in patients with unexplained and mild male infertility. [ABSTRACT FROM AUTHOR]

To maintain a thermal balance when experiencing cold, humans reduce heat loss and enhance heat production. A potent and rapid mechanism for heat generation is shivering. Research has shown that women prefer a warmer environment and feel less comfortable than men in the same thermal condition. Using the Blanketrol ® III, a temperature management device commonly used to study brown adipose tissue activity, we tested whether the experimental temperature (T E ) at which men and women start to shiver differs. Twenty male and 23 female volunteers underwent a cooling protocol, starting at 24 °C and gradually decreasing by 1-2 °C every 5 min until an electromyogram detected the shivering or the temperature reached 9 °C. Women started shivering at a higher T E than men (11.3 ± 1.8 °C for women vs 9.6 ± 1.8 °C for men, P = 0.003). In addition, women felt cool, scored by a visual analogue scale, at a higher T E than men (18.3 ± 3.0 °C for women vs 14.6 ± 2.6 °C for men, P < 0.001). This study demonstrates a sex difference in response to cold exposure: women require shivering as a source of heat production earlier than men. This difference could be important and sex should be considered when using cooling protocols in physiological studies., (Copyright © 2018 The Authors. Published by Elsevier Ltd.. All rights reserved.)

In the veterinary practice, there is a need for a diagnostic tool to check the gonadal status in female dogs because it may be difficult to determine whether a female animal has been spayed or whether there are ovarian remnants. Although less prevalent, a similar situation pertains to male dogs. Anti-Müllerian hormone (AMH) is an important regulator of gonadal function and is a specific gonadal product that can be determined in circulation. The objective of this study was to develop and test a canine blood AMH assay as a diagnostic tool to determine the presence of functional gonadal tissue in dogs. A prospective study with a training-validation set paradigm was used. A canine AMH assay was developed and serum and plasma AMH concentrations were determined in blood samples from 46 intact female dogs, 48 spayed females, 50 intact males, and 48 castrated males collected at two separate institutes. Using a training-validation set paradigm, it was found that using cutoff values of 1.1 ng/mL (female) and 5.5 ng/mL (male) AMH, the assay reported excellent specificity and sensitivity of 100% and 90% in female dogs, and good specificity and sensitivity of 100% and 76%, in male dogs, respectively. The sensitivity in male dogs could be further enhanced by including a serum testosterone determination. This newly developed canine AMH assay is a valuable diagnostic tool to determine gonadal status in veterinary medicine., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Objective: The objective of this study was to determine the aetiological spectrum of disorders of sex development (DSD) in a large cohort of underprivileged and undiagnosed patients from Indonesia., Methods: A total of 286 patients with atypical external and/or internal genitalia were evaluated using clinical, hormonal, molecular genetic and histological parameters., Results: The age (years) at presentation was 0-0·5 in 41 (14·3%), >0·5-12 in 181 (63·3%) and >12 in 64 cases (22·4%). 46,XY DSD was most common (68·2%, n = 195), 46,XX DSD was found in 23·4% (n = 67) and sex chromosomal DSD in 8·4% (n = 24). In 61·2% of 46,XX DSD patients, 17·9% of 46,XY DSD patients and all sex chromosome DSD patients (29·4% in total), a final diagnosis was reached based on genetic or histological gonadal tissue evaluation. 17-hydroxyprogesterone and androstenedione levels were the most distinctive parameters in 46,XX DSD patients. In 46,XY DSD, diagnostic groups were identified based on the external masculinization score: androgen action disorder (AAD), unknown male undermasculinization (UMU), and gonadal dysgenesis (GD). LH, FSH and testosterone levels were most informative especially in the older age group. HCG tests were of no additional value as no patients with androgen synthesis disorders were found. Hormonal profiles of patients with sex chromosome DSD and a Y-chromosome sequence containing karyotype showed high levels of LH and FSH, and low levels of AMH, inhibin B and testosterone compared with the normal male range. Gene mutations were found in all patients with CAH, but in only 24·5% and 1·8% of patients with AAD and UMU. In 32% of 46,XY GD patients, copy number variants of different genes were found., Conclusion: A stepwise diagnostic approach led to a molecularly or histologically proven final diagnosis in 29·4% of the patients. The most informative parameters were serum levels of 17-hydroxyprogesterone and androstenedione in 46,XX DSD patients, and serum LH, FSH and testosterone levels in 46,XY DSD patients., (© 2016 John Wiley & Sons Ltd.)

Aim: Dietary restriction (DR) and fasting (FA) induce robust protection against the detrimental effects of renal ischemia-reperfusion injury (I/RI). Several mechanisms of protection have been proposed, such as hormesis. Hormesis is defined as a life-supporting beneficial effect resulting from the cellular responses to single or multiple rounds of (mild) stress. The cold exposure (CE) model is a stress model similar to DR, and has been shown to have hormetic effects and has proved to increase longevity. CE is considered to be the most robust method to increase metabolism through activation of brown adipocytes. BAT has been considered important in etiology of obesity and its metabolic consequences., Materials and Methods: Since DR, FA, and CE models are proposed to work through hormesis, we investigated physiology of adipose tissue and effect on BAT in these models and compared them to ad libitum (AL) fed mice. We also studied the differential effect of these stress models on immunological changes, and effect of CE on renal I/RI., Key Findings: We show similar physiological changes in adiposity in male C57Bl/6 mice due to DR, FA and CE, but the CE mice were not protected against renal I/RI. The immunophenotypic changes observed in the CE mice were similar to the AL animals, in contrast to FA mice, that showed major immunophenotypic changes in the B and T cell development stages in primary and secondary lymphoid organs., Significance: Our findings thus demonstrate that DR, FA and CE are hormetic stress models. DR and FA protect against renal I/IR, whereas CE could not., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Objective: Brown adipose tissue (BAT) can generate heat by burning fatty acids, a process mediated by uncoupling protein 1 (UCP1). White adipose tissue (WAT) depots can gain BAT-like properties, and various studies have suggested that females have more active BAT or BAT-like WAT. We studied sex differences in BAT-like properties of human perirenal adipose tissue., Methods: Perirenal and subcutaneous adipose tissue was obtained from 20 male and 24 female healthy live kidney donors. Mesenchymal stem cells (MSCs), adipocyte precursor cells, were isolated from these depots to study whether intrinsic factors control BAT-like properties of the adipose tissue depots., Results: When average outside temperature a week before harvesting was below 11°C, brown-like adipocytes expressing UCP1 were present in perirenal adipose tissue of women, but not of men. MSCs derived from perirenal adipose tissue expressed significantly more UCP1 when from female origin compared to male origin (P = 0.009). However, UCP1 protein content and oxygen consumption rate did not differ between adipocytes derived from male and female perirenal MSCs., Conclusions: Female perirenal adipose tissue has a higher potency to gain BAT-like properties than male perirenal adipose tissue. The degree of gaining BAT-like properties depends on sex-specific intrinsic factors and environmental triggers such as temperature., (© 2015 The Obesity Society.)

Objective: To assess whether an FSH receptor polymorphism (Asn680Ser, rs6166) can affect the outcome of ovulation induction in normogonadotropic (World Health Organization class 2 [WHO2]) anovulatory subfertile women., Design: Prospective, longitudinal, cohort study., Setting: University-based fertility unit., Patient(s): A total of 240 consecutive women diagnosed with WHO2 anovulatory subfertility who underwent ovulation induction therapy. Results were replicated in a retrospective cohort of 185 patients with polycystic ovary syndrome (PCOS) (Rotterdam criteria)., Intervention(s): Ovulation induction using clomiphene citrate (CC) as first-line and exogenous gonadotropins (exFSH) as second-line therapy., Main Outcome Measure(s): Clomiphene-resistant anovulation (CRA), clomiphene failure (CCF), and ongoing pregnancy rate., Result(s): Genotyped patients (n = 159) were similar to nongenotyped women (n = 81) regarding clinical characteristics and outcomes of ovulation induction. The 680(Ser) allele was associated with CRA. A pooled analysis of both cohorts showed an 89% higher chance of CRA after CC treatment (odds ratio 1.9 [95% confidence interval 1.1-3.3]) in homozygous carriers of the FSH receptor variant (680(Ser/Ser)). A lower chance of ongoing pregnancy (hazard ratio 0.51 [95% confidence interval 0.27-0.98]) was observed among these patients during CC treatment in the prospective cohort., Conclusion(s): An FSH receptor polymorphism is associated with CRA during treatment with clomiphene citrate. These data may be used to design a treatment algorithm that is more efficacious and better tailored to the individual patient., (Copyright © 2015 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Context: The acylated/unacylated ghrelin (AG/UAG) ratio has been reported to range from 0·02 to 0·3, suggesting biologically relevant independent regulation of each ghrelin isoform. However, AG is deacylated to UAG by esterases in blood samples, and esterase inhibition is critical for their accurate measurement. Our hypothesis is that at least part of the variation in reported AG and UAG values is due to inconsistent sample preparation., Design: A non-interventional study. Quantification with two different, commercially available, ELISA formats of AG and UAG in venous plasma stabilized or not with 4-(2-aminoethyl) benzenesulphonyl fluoride (AEBSF) and stored for 0-6 months at -20 or -80 °C., Participants: Healthy, non-obese, adults (n = 8; 4 women), age 26-42 yrs, after an overnight fast., Measurements: AG and UAG stability following different methods of sample treatment and storage., Results: Non-AEBSF plasma contained low AG and high UAG (>270 pg/ml) indicating rapid conversion of AG to UAG. However, AEBSF plasma, stored at -80 °C and measured at 0, 1, 3 and 6 months contained AG and UAG ranges of 12-350 and 17-170 pg/ml, respectively. Mean (SEM) AG/UAG ratios were 1·7(0·3), 1·2(0·2), 1·5(0·3) and 1·8(0·5) at each time point with no significant effect of storage period., Conclusions: AG and UAG levels measured in AEBSF-stabilized plasma indicate that the AG/UAG ratio is markedly higher than previously described and that UAG is a physiological component of the circulation. This highlights the importance of immediately stabilizing blood samples on collection for determination of both AG and UAG concentrations and provides a valuable tool for their measurement in physiological and interventional studies., (© 2014 John Wiley & Sons Ltd.)

Brown adipose tissue (BAT) and brown-like cells in white adipose tissue (WAT) can dissipate energy through thermogenesis, a process mediated by uncoupling protein 1 (UCP1). We investigated whether stress hormones ACTH and corticosterone contribute to BAT activation and browning of WAT. ACTH and corticosterone were studied in male mice exposed to 4 or 23°C for 24 h. Direct effects were studied in T37i mouse brown adipocytes and primary cultured murine BAT and inguinal WAT (iWAT) cells. In vivo effects were studied using (18)F-deoxyglucose positron emission tomography. Cold exposure doubled serum ACTH concentrations (P=0.03) and fecal corticosterone excretion (P=0.008). In T37i cells, ACTH dose-dependently increased Ucp1 mRNA (EC50=1.8 nM) but also induced Ucp1 protein content 88% (P=0.02), glycerol release 32% (P=0.03) and uncoupled respiration 40% (P=0.003). In cultured BAT and iWAT, ACTH elevated Ucp1 mRNA by 3-fold (P=0.03) and 3.7-fold (P=0.01), respectively. In T37i cells, corticosterone prevented induction of Ucp1 mRNA and Ucp1 protein by both ACTH and norepinephrine in a glucocorticoid receptor (GR)-dependent fashion. ACTH and GR antagonist RU486 independently doubled BAT (18)F-deoxyglucose uptake (P=0.0003 and P=0.004, respectively) in vivo. Our results show that ACTH activates BAT and browning of WAT while corticosterone counteracts this., (© FASEB.)

Cushing's disease, a hypercortisolemic state induced by an ACTH overexpressing pituitary adenoma, causes increased morbidity and mortality. Selective antagonism of the melanocortin type 2 receptor (MC2R) may be a novel treatment modality. Five structurally related peptides with modified HFRW sites but intact putative MC2R binding sites were tested for antagonistic activity at MC1R, MC2R/MRAP, MC3R, MC4R and MC5R. Two of these peptides (GPS1573 and GPS1574) dose-dependently antagonized ACTH-stimulated MC2R activity (IC50s of 66±23 nM and 260±1 nM, respectively). GPS1573 and 1574 suppressed the Rmax but not EC50 of ACTH on MC2R, indicating non-competitive antagonism. These peptides did not antagonize α-MSH stimulation of MC1R and antagonized MC3, 4 and 5R at markedly lower potency. GP1573 and GPS1574 antagonize MC4R with IC50s of 950 nM and 3.7 μM, respectively. In conclusion, two peptide antagonists were developed with selectivity for MC2R, forming a platform for development of a medical treatment for Cushing's disease., (Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.)

The ovary is under control of the hypothalamus and pituitary through the glycoprotein hormones LH and FSH. These hormones undergo a cyclic variation which results in the selection of the species-specific number of follicles that will ovulate during the cycle. Where LH is the main ovulatory hormone and regulator of corpus luteum function, FSH plays an essential role in the cyclic recruitment of the follicles. Within the microenvironment of the ovary, growth factors affect this dominant control of FSH by regulating the FSH sensitivity of individual follicles. In this review we discuss the role of anti-Müllerian hormone (AMH) and bone morphogenetic proteins (BMPs) in this process., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Background: A two-step selection procedure, consisting of a non-academic and an academic step, was recently shown to select students with a 2.6 times lower risk of early dropout and a higher clerkship Grade Point Average (GPA) than lottery-admitted controls., Aim: To determine the relative contribution of the non-academic and academic steps to differences found in student performance., Method: Lottery-admitted students (n = 653) and three groups of selection procedure participants were compared on early dropout rate and clerkship GPA: (1) all participants (n = 1676), (2) participants who passed step 1, and (3) participants who passed step 2., Results: Selection procedure participation resulted in a 4.4% lower dropout rate than lottery admission and this difference increased to 5.2% after step 1 and to 8.7% after step 2. Clerkship GPA was significantly higher for participants who passed step 1 than for their lottery-admitted controls. This difference remained significant after the rejection of students on academic criteria in step 2., Conclusion: The lower dropout rate of selected students is related to both self-selection of participants before the start of the selection procedure and the academic part of the selection procedure. The higher clerkship GPA of selected students is almost exclusively related to the non-academic selection criteria.

Background: There is a need for outcome-based studies on strategies for supporting at-risk medical students that use long-term follow-up and contemporaneous controls., Aim: To measure the effect of a short integrated study skills programme (SSP) on the study progress of at-risk medical students., Methods: First-year students identified as at-risk of academic failure at 7 months after enrolment were invited to participate in the randomised controlled trial. Participants were randomly assigned to the SSP group or to a control group receiving standard academic support. Effects of SSP were measured on the short (passed first exam after intervention), medium (obtained enough credits to proceed to second year) and long term (completed first-year curriculum within 2 years)., Results: SSP participants (n=43) more often passed the first exam after the intervention than controls (n=41; 30% versus 12%; X2(1)=4.06, p<0.005, effect size=0.22), in particular those who had previously passed at least one exam. No medium or long-term effect was found. Participants who had attended four or five SSP sessions outperformed those who had attended fewer sessions on all outcome measures., Conclusion: A short, integrated SSP benefited some, but not all students. Our advice is to focus support efforts on at-risk students who have demonstrated commitment and academic potential.

Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women in their reproductive age, is characterized by both reproductive and metabolic features. Recent studies in human, nonhuman primates, and sheep suggest that hyperandrogenism plays an important role in the development of PCOS. We investigated whether chronic dihydrotestosterone (DHT) exposure in mice reproduces both features of PCOS. Such a model would allow us to study the mechanism of association between the reproductive and metabolic features in transgenic mice. In this study, prepubertal female mice received a 90 d continuous release pellet containing the nonaromatizable androgen DHT or vehicle. At the end of the treatment period, DHT-treated mice were in continuous anestrous, their ovaries contained an increased number of atretic follicles, with the majority of atretic antral follicles having a cyst-like structure. Chronic DHT-exposed mice had significantly higher body weights (21%) than vehicle-treated mice. In addition, fat depots of DHT-treated mice displayed an increased number of enlarged adipocytes (P < 0.003). Leptin levels were elevated (P < 0.013), adiponectin levels were diminished (P < 0.001), and DHT-treated mice were glucose intolerant (P < 0.001). In conclusion, a mouse model of PCOS has been developed showing reproductive and metabolic characteristics associated with PCOS in women.

Objective: To describe changes of anti-Müllerian hormone (AMH) and inhibin B during low-dose gonadotropin ovulation induction (OI) treatment in women with polycystic ovary syndrome (PCOS), and thus disturbed selection of the dominant follicle., Design: Observational study., Setting: A referral fertility clinic., Patient(s): Women with PCOS (n = 48) and normo-ovulatory women (n = 23)., Intervention(s) and Main Outcome Measure(s): Serum AMH, inhibin B, FSH, and E(2) concentrations were measured at start of stimulation, on the day of follicle selection, and at administration of hCG during OI cycles and were compared with concentration measured during the normal menstrual cycle., Result(s): Development of a single dominant follicle was observed in 92% of all OI cycles, reflected by similar E(2) concentrations compared with those in spontaneous cycles. AMH concentrations were constant during low-dose ovarian stimulation. Inhibin B concentrations remained elevated in patients with PCOS, suggesting prolonged survival of small antral follicles, whereas in controls inhibin B concentrations declined during the late follicular phase., Conclusion(s): The lack of change in AMH and inhibin B concentrations suggest that follicle dynamics during low-dose stimulation seem different from those during controlled ovarian hyperstimulation. In addition, constant AMH and inhibin B levels suggest that neither AMH nor inhibin B is an accurate marker of ovarian response after low-dose gonadotropin OI in patients with PCOS., (Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

The composition of the plasma membrane affects the responsiveness of cells to metabolically important hormones such as insulin and vasoactive intestinal peptide. Ghrelin is a metabolically regulated hormone that activates the G protein-coupled receptor GH secretagogue receptor type 1a (GHSR) not only in the pituitary gland but also in peripheral tissues such as the pancreas, stomach, and T cells in the circulation. We have investigated the effects of lipids and altered plasma membrane composition on GHSR activation. Oligounsaturated fatty acids (OFAs) disrupt the structure of membranes and make them more fluid. Prolonged (96 h), but not acute, treatment of the GHSR cells with the 18C OFAs oleic and linoleic acid caused a significant increase in sensitivity of the receptor to ghrelin (EC(50) reduced by a factor of 2.4 and 2.9 at 60 and 120 microM OFAs, respectively). OFAs were found to block the inhibitory effects of ghrelin pretreatment on subsequent ghrelin responsiveness, suggesting that OFAs suppress desensitization of GHSR. Radioligand displacement studies did not show a significant shift in receptor binding after incubation with OFAs. However, it was found that OFA treatment suppressed GHSR internalization, likely explaining OFA-induced refractoriness to ligand-induced desensitization. The involvement of lipid rafts in this process was indicated by the altered responsiveness of GHSR under conditions that alter membrane cholesterol. In conclusion, our findings demonstrate the importance of membrane composition for GHSR activation and desensitization and indicate at least part of the mechanism through which OFAs and cholesterol could affect ghrelin's activity in vivo.

The rapid expansion of mutant mouse colonies for biomedical research has resulted in lack of space at laboratory animal facilities and increasing risks of losing precious lines. These challenges require cheap and effective methods in addition to freezing embryos and sperm to archive the expanding mutant mouse lines. Cryopreservation of mouse ovarian tissue has been reported, but the application in the diverse mutant lines and genetic backgrounds has not yet been studied. In this study, juvenile ovaries (10-day-old) collected from genetically modified mouse lines were cryopreserved using high concentrations of cryoprotectants (dimethyl sulfoxide (Me(2)SO) and ethylene glycol (EG)) and instrumented ultra-rapid freezing. The validation of the frozen ovary batches was assessed by orthotopically transplanting a thawed ovary into a nearly completely ovariectomized mature female (congenic with the ovary donor). After 2 weeks of recovery, the ovary recipient was continuously paired with a male (congenic with the ovary donor) to evaluate the fertility of the recipient and delivered offspring were genotyped to evaluate the continued functionality of the grafted ovary. The recipient females delivered genetically modified offspring starting 6 weeks after ovary transplantation and lasting up to 6 months. The presented cryopreservation and transplantation protocols enabled retrieval of the genetic modification in 20 (from 22) genetically modified mutant mouse models on a C57BL/6 (17), FVB (2), or BALB/c (1) background. The thawed ovaries functioned after successful orthotopic allotransplantation to congenic wild-type recipients and produced mutant offspring, which allowed recreation of the desired genotype as a heterozygote on the proper genetic background. The results indicate that cryopreservation of mouse ovaries is a promising method to preserve genetic modification of the increasing number of mutant mouse models and can be used as a model for ovary cryopreservation using a variety of mouse mutants., (Copyright 2009 Elsevier Inc. All rights reserved.)

Objective: To evaluate serum anti-Müllerian hormone (AMH) in well-characterized men with normal and reduced sperm concentration and in men with a history of or persistent maldescended testes as a possible clinical marker of male factor infertility and/or maldescended testes., Design: Retrospective analysis of 199 men selected from our database (Androbase)., Setting: The university-based Institute of Reproductive Medicine., Patient(s): One hundred eight men with normal and 60 men with reduced sperm concentration without known cause of infertility and additionally 31 infertile men with current or former maldescended testes were evaluated., Intervention(s): Serum AMH was analyzed by an in-house ELISA., Main Outcome Measure(s): Hormone and semen parameters were compared and correlated with AMH., Result(s): No significant differences were found in AMH levels. Only in men with maldescended testes did AMH correlate negatively with FSH and positively with testicular volume and sperm concentration. No correlations between AMH and LH or testosterone (T) were found., Conclusion(s): Anti-Müllerian hormone serum levels are not significantly affected by impaired spermatogenesis in general but are correlated with spermatogenic parameters in men with current or former maldescended testes. Therefore, AMH measurement does not improve clinical routine diagnostics but should be evaluated further in patients with maldescended testes. Anti-Müllerian hormone might serve as a marker of Sertoli cell number, function, and/or maturation in these men.

Worldwide, breast cancer is the most frequently occurring malignancy in women. Early age at full term pregnancy has a protective effect against breast cancer. Evidence coming from a rat breast cancer model suggests a possible role for the pregnancy hormone hCG, a ligand of the LH receptor, as a mediator for this effect. In a previous study, we found that a common polymorphism in the LH receptor associates with tumor progression in premenopausal breast cancer patients, as carriers of the variant receptor showed a shorter disease free survival compared to non-carriers. How hCG and its receptor exert their effects on breast cancer, however, is unclear. One possibility is that these effects take place through LH receptors present in the ovaries, thereby influencing steroid hormone production. Another possibility is that the effects take place through LH receptors present in breast tumor cells themselves, as some studies have detected the receptor in both normal and neoplastic breast tissues and in breast cancer cell lines. To investigate whether a direct effect of LH signaling in breast cancer is likely, we measured LH receptor mRNA expression levels in 1551 breast tumors and 42 different human breast cancer cell lines using a qRT-PCR with a wide dynamic range. In addition, associations between LH receptor expression and clinico-pathologic factors were investigated. Assay validation showed that as little as ?10 copies per reaction volume of LH receptor cDNA could still be detected by our assay. We show that LH receptors are undetectable in 62% of breast tumor samples and 41 of 42 breast cancer cell lines. For the remaining samples we found expression levels to be very low. Although low, expression of the LH receptor appears to be associated with normal breast cells, favorable tumor characteristics and low tumor percentage. Since expression of the LH receptor in breast cancer cells is very low, it almost excludes the possibility of direct signaling effects. We therefore conclude that signaling effects of the LH receptor on breast cancer most likely take place by an indirect pathway through the ovaries.

Background: Polycystic ovaries display an increased number of pre-antral and antral follicles compared with normal ovaries, suggesting that early and late follicle development are disturbed. The pathophysiology of this process is poorly understood. Since the transforming growth factor beta family members, anti-Müllerian hormone (AMH) and bone morphogenetic proteins (BMPs), inhibit FSH sensitivity, their signalling may contribute to the aberrant follicle development in these women. Here, we investigated the role of ALK2, a type I receptor for AMH/BMP signalling, in PCOS using a genetic approach., Methods: Seven single nucleotide polymorphisms in the ACVR1 gene, encoding ALK2, were genotyped in 359 PCOS patients and 30 normo-ovulatory and 3543 population-based control women, and haplotypes were determined. Subsequently, the association of ACVR1 variants with ovarian parameters and hormone levels was investigated., Results: The polymorphisms rs1220134, rs10497189 and rs2033962 and their corresponding haplotypes did not show different frequencies from controls, but were associated with AMH levels in PCOS women (P = 0.001, P = 0.002 and P = 0.007, respectively). Adjustment for follicle number revealed that the association with AMH levels was, in part, independent from follicle number, suggesting that variants in ACVR1 also influence AMH production per follicle., Conclusions: Genetic variation within ACVR1 is associated with AMH levels and follicle number in PCOS women, suggesting that ALK2 signalling contributes to the disturbed folliculogenesis in PCOS patients.

Anti-Müllerian hormone (AMH) has important roles in postnatal ovarian function. Produced by ovarian granulosa cells, AMH is involved in initial follicle development. In fact, serum AMH level correlates with ovarian follicle number. In patients with polycystic ovary syndrome (PCOS), AMH levels are elevated, which indicates its potential relevance in PCOS diagnosis and management. AMH represents a useful clinical marker for the assessment of ovarian reserve in cases of subfertility caused by advanced age in women. A potential role for AMH in dominant follicle selection has also been suggested. Future challenges comprise the availability of a well-standardized assay and the development of AMH agonists and antagonists as possible tools to manipulate ovarian function for contraception or ovarian longevity.

A chemically induced model of ovarian failure has been developed in rodents, and was used to test whether or not anti-Müllerian hormone (AMH) can be used as a non-invasive measure of primordial follicle numbers. Repeated exposures of mice to 4-vinylcyclohexene diepoxide (VCD) induce loss of primordial and earliest growing ovarian follicles. An accelerated exposure regimen was used to eliminate small ovarian follicles in C57BL6/J mice (240mg VCD/kg/day, 5 days, i.p.). Follicle populations were determined and correlated with circulating AMH levels. Exposures decreased only primordial and small primary follicles by 96% on day 16 after initiating exposures, followed by almost complete follicle elimination on days 37-100. AMH levels in VCD-exposed mice were similar to vehicle-treated mice on day 16, but became significantly lower or undetectable at later time points. Thus, AMH correlated well with growing follicle numbers. AMH only correlated with primordial follicles at time points after ovarian insult at which their loss led to decreased growing follicle numbers.

The luteinizing hormone (LH) receptor plays an essential role in male and female gonadal function. Together with the follicle-stimulating hormone (FSH) and thyroid stimulating hormone (TSH) receptors, the LH receptor forms the family of glycoprotein hormone receptors. All glycoprotein hormone receptors share a common modular topography, with an N-terminal extracellular ligand binding domain and a C-terminal seven-transmembrane transduction domain. The ligand binding domain consists of 9 leucine-rich repeats, flanked by N- and C-terminal cysteine-rich regions. Recently, crystal structures have been published of the extracellular domains of the FSH and TSH receptors. However, the C-terminal cysteine-rich region (CCR), also referred to as the "hinge region," was not included in these structures. Both structure and function of the CCR therefore remain unknown. In this study we set out to characterize important domains within the CCR of the LH receptor. First, we mutated all cysteines and combinations of cysteines in the CCR to identify the most probable disulfide bridges. Second, we exchanged large parts of the LH receptor CCR by its FSH receptor counterparts, and characterized the mutant receptors in transiently transfected HEK 293 cells. We zoomed in on important regions by focused exchange and deletion mutagenesis followed by alanine scanning. Mutations in the CCR specifically decreased the potencies of LH and hCG, because the potency of the low molecular weight agonist Org 41841 was unaffected. Using this unbiased approach, we identified Asp(330) and Tyr(331) as key amino acids in LH/hCG mediated signaling.

Polymorphic variation of the LHR gene may affect receptor function and accordingly may influence ovarian steroid hormone action, including steroid hormone-dependent clinical outcome. The functional effects of two single nucleotide polymorphisms (SNPs), i.e. LHR 291Asn/Ser (rs12470652) and 312Ser/Asn (rs2293275) in the biologically interesting exon 10 of the LHR gene are described. Furthermore, ethnic diversity in allele frequencies and genotype distributions of both SNPs was determined. In addition associations with breast cancer were studied in 751 breast cancer patients. In vitro transfection studies revealed altered glycosylation status and increased receptor sensitivity for the 291Ser LHR variant. No functional consequences were observed for the 312SerAsn LHR SNP. The LHR 312Asn allele was slightly more often present in two independent breast cancer patient cohorts as compared to controls (OR=1.15; p=0.03 and 1.26; p=0.001, respectively). In conclusion, although functional changes of the LHR 291Ser candidate allele were observed, no associations with breast cancer were found, while the LHR 312Asn allele can be regarded as a weak breast cancer risk allele.

Acylated and unacylated ghrelin (AG and UAG) are gut hormones that exert pleiotropic actions, including regulation of insulin secretion and glucose metabolism. In this study, we investigated whether AG and UAG differentially regulate portal and systemic insulin levels after a glucose load. We studied the effects of the administration of AG (30 nmol/kg), UAG (3 and 30 nmol/kg), the ghrelin receptor antagonist [D-Lys(3)]GHRP-6 (1 micromol/kg), or various combinations of these compounds on portal and systemic levels of glucose and insulin after an intravenous glucose tolerance test (IVGTT, d-glucose 1 g/kg) in anesthetized fasted Wistar rats. UAG administration potently and dose-dependently enhanced the rise of insulin concentration induced by IVGTT in the portal and, to a lesser extent, the systemic circulation. This UAG-induced effect was completely blocked by the coadministration of exogenous AG at equimolar concentrations. Similarly to UAG, [D-Lys(3)]GHRP-6, alone or in combination with AG and UAG, strongly enhanced the portal insulin response to IVGTT, whereas exogenous AG alone did not exert any further effect. Our data demonstrate that, in glucose-stimulated conditions, exogenous UAG acts as a potent insulin secretagogue, whereas endogenous AG exerts a maximal tonic inhibition on glucose-induced insulin release.

Recent findings demonstrate that the effects of ghrelin can be abrogated by co-administered unacylated ghrelin (UAG). Since the general consensus is that UAG does not interact with the type 1a growth hormone secretagogue receptor (GHS-R), a possible mechanism of action for this antagonistic effect is via another receptor. However, functional antagonism of the GHS-R by UAG has not been explored extensively. In this study we used human GHS-R and aequorin expressing CHO-K1 cells to measure [Ca(2+)](i) following treatment with UAG. UAG at up to 10(-5)M did not antagonize ghrelin induced [Ca(2+)](i). However, UAG was found to be a full agonist of the GHS-R with an EC(50) of between 1.6 and 2 microM using this in vitro system. Correspondingly, UAG displaced radio-labeled ghrelin from the GHS-R with an IC(50) of 13 microM. In addition, GHS-R antagonists were found to block UAG induced [Ca(2+)](i) with approximately similar potency to their effect on ghrelin activation of the GHS-R, suggesting a similar mode of action. These findings demonstrate in a defined system that UAG does not antagonize activation of the GHS-R by ghrelin. But our findings also emphasize the importance of assessing the concentration of UAG used in both in vitro and in vivo experimental systems that are aimed at examining GHS-R independent effects. Where local concentrations of UAG may reach the high nanomolar to micromolar range, assignment of GHS-R independent effects should be made with caution.

Background: Ovarian failure as a complication of uterine artery embolization (UAE) for symptomatic uterine fibroids has raised concerns about this new treatment modality., Methods: We investigated the occurrence of ovarian reserve reduction in a randomized trial comparing UAE and hysterectomy by measuring follicle stimulating hormone (FSH) and anti-Mullerian hormone (AMH). A total of 177 pre-menopausal women with menorrhagia due to uterine fibroids were included (UAE:n=88; hysterectomy:n=89). FSH and AMH were measured at baseline and at several time-points during the 24 months follow-up period. Follow-up AMH levels were also compared to the expected decrease due to ovarian ageing during the observational period., Results: FSH increased significantly compared to baseline in both groups after 24 months follow-up (within group analysis: UAE:+12.1; P=0.001; hysterectomy:+16.3; P<0.0001). No differences in FSH values between the groups were found (P=0.32). At 24 months after treatment the number of patients with FSH levels>40 IU/l was 14/80 in the UAE group and 17/73 in the hysterectomy group (relative risk=0.75; P=0.37). AMH was measured in 63 patients (UAE: n=30; hysterectomy: n=33). After treatment AMH levels remained significantly decreased during the entire follow-up period only in the UAE group compared to the expected AMH decrease due to ageing. No differences were observed between the groups., Conclusions: This study shows that both UAE and hysterectomy affect ovarian reserve. This results in older women becoming menopausal after the intervention. Therefore, the application of UAE in women who still wish to conceive should only be considered after appropriate counselling.

Background: In mice, anti-Müllerian hormone (AMH) inhibits primordial follicle recruitment and decreases FSH sensitivity. Little is known about the role of AMH in human ovarian physiology. We hypothesize that in women AMH has a similar role in ovarian function as in mice and investigated this using a genetic approach., Methods: The association of the AMH Ile(49)Ser and the AMH type II receptor (AMHR2) -482 A > G polymorphisms with menstrual cycle characteristics was studied in a Dutch (n = 32) and a German (n = 21) cohort of normo-ovulatory women., Results: Carriers of the AMH Ser(49) allele had higher serum estradiol (E(2)) levels on menstrual cycle day 3 when compared with non-carriers in the Dutch cohort (P = 0.012) and in the combined Dutch and German cohort (P = 0.03). Carriers of the AMHR2 -482G allele also had higher follicular phase E(2) levels when compared with non-carriers in the Dutch cohort (P = 0.028), the German cohort (P = 0.048) and hence also the combined cohort (P = 0.012). Women carrying both AMH Ser(49) and AMHR2 -482G alleles had highest E(2) levels (P = 0.001). For both polymorphisms no association with serum AMH or FSH levels was observed., Conclusions: Polymorphisms in the AMH and AMHR2 genes are associated with follicular phase E(2) levels, suggesting a role for AMH in the regulation of FSH sensitivity in the human ovary.

Objective: To investigate whether serum levels of follicle-stimulating hormone (FSH), inhibin B, and anti-Müllerian hormone (AMH) can be used as predictors of recovery of ovarian function in anorexia nervosa after weight gain., Design: Follow-up cohort study., Setting: Two specialized treatment centers for eating disorders, one for adolescents (aged between 12 and 17 years) and one for adults (older than the age of 17 years)., Patient(s): Sixty-one young women (mean age, 18.2 years) with anorexia nervosa., Intervention(s): None (standard treatment program)., Main Outcome Measure(s): Time to recovery of menses., Result(s): Forty-two (69%) patients recovered in weight within the 1st year, of which only 24 (39%) reached resumption of regular menstrual cycles. Next to weight gain itself, initial ovarian endocrine markers such as FSH, inhibin B, and AMH hormone were capable of predicting chances for resumption of menses in a multivariate analysis with time to recovery as the main outcome measure., Conclusion(s): Initial ovarian endocrine markers FSH, inhibin B, and AMH can predict successful recovery of ovarian function in anorexia nervosa patients undergoing treatment to gain weight.

Background: Breast cancer development and progression are dependent on estrogen activity. In premenopausal women, estrogen production is mainly regulated through the hypothalamic-pituitary-gonadal (HPG) axis., Methods: We have investigated the prognostic significance of two variants of genes involved in the HPG-axis, the GnRH (encoding gonadotropin-releasing hormone) 16Trp/Ser genotype and the LHR (encoding the luteinizing hormone receptor) insLQ variant, in retrospectively collected premenopausal breast cancer patients with a long follow-up (median follow-up of 11 years for living patients)., Results: Carriership was not related with breast cancer risk (the case control study encompassed 278 premenopausal cases and 1,758 premenopausal controls). A significant adverse relationship of the LHR insLQ and GnRH 16Ser genotype with disease free survival (DFS) was observed in premenopausal (hormone receptor positive) breast cancer patients. In particular, those patients carrying both the GnRH 16Ser and LHR insLQ allele (approximately 25%) showed a significant increased risk of relapse, which was independent of traditional prognostic factors (hazard ratio 2.14; 95% confidence interval 1.32 to 3.45; P = 0.002)., Conclusion: We conclude that the LHR insLQ and GnRH 16Ser alleles are independently associated with shorter DFS in premenopausal patients. When validated, these findings may provide a lead in the development of tailored treatment for breast cancer patients carrying both polymorphisms.

Both unacylated ghrelin (UAG) and acylated ghrelin (AG) exert metabolic effects. To investigate the interactions between AG and UAG on ghrelin receptors we evaluated the effects of AG and UAG on INS-1E rat insulinoma cells, using insulin secretion after 30min static incubation as a read-out. A possible involvement of the growth hormone secretagogue receptor type 1a (GHS-R1a) or the corticotropin-releasing factor 2 (CRF2) receptor (CRF2R), as a putative receptor for UAG, was also studied determining their mRNA expression and the functional effects of receptor antagonists on insulin release. Both UAG and AG stimulated insulin release dose-dependently in the nanomolar range. The AG-induced insulin output was antagonized by two GHS-R1a antagonists ([d-Lys(3)]GHRP-6 and BIM28163), which did not block UAG actions. These effects occurred in the presence of low levels of GHS-R1a mRNA. Neither CRF2R expression nor effects of the CRF2R antagonist (astressin(2)B) on insulin output were observed. In conclusion, we provide a sensitive and reproducible assay for specific effects of UAG, which in this study is responsible for insulin release by INS-1E cells. Our data support the existence of a specific receptor for UAG, other than the CRF2R and GHS-R1a. The stimulatory effect on insulin secretion by AG in this cell line is mediated by the GHS-R1a.

This paper reviews the role of anti-Müllerian hormone, a member of the TGF(beta) family signaling through a BMP-like pathway, in the ovary. In vivo and in vitro studies showed that AMH has an inhibitory effect on primordial follicle recruitment and it decreases the sensitivity of follicles for the FSH-dependent selection for dominance. Besides its functional role in the ovary, AMH serum level serves as an excellent candidate marker of ovarian reserve.

Objective: The aim of this study was to assess which of the basal ovarian reserve markers provides the best reflection of the changes occurring in ovarian function over time (i.e., reproductive aging)., Design: Prospective longitudinal study., Setting: Healthy volunteers in an academic research center., Patient(s): Eighty-one women with normal reproductive performance during the course of their lives were longitudinally assessed. In this select group of women, becoming chronologically older was considered as a proxy variable for becoming older from a reproductive point of view., Intervention(s): The women were assessed twice, with on average a 4-year interval (T(1) and T(2)). The number of antral follicles on ultrasound (AFC) and blood levels of antimullerian hormone (AMH), FSH, inhibin B, and E(2) were assessed., Main Outcome Measure(s): Longitudinal changes of the markers mentioned and the consistency of these parameters over time., Result(s): The mean ages at T(1) and T(2) were 39.6 and 43.6 years, respectively. Although AFC was strongly associated with age in a cross-sectional fashion, it did not change over time. The AMH, FSH, and inhibin B levels showed a significant change over time, in contrast to E(2) levels. The AMH and AFC were highly correlated with age both at T(1) and T(2), whereas FSH and inhibin B predominantly changed in women more than 40 years of age. To assess the consistency of these parameters over time, we investigated whether a woman's individual level above or below the mean of her age group at T(1) remained above or below the mean of her age group at T(2). Serum AMH concentrations showed the best consistency, with AFC as second best. The FSH and inhibin B showed only modest consistency, whereas E(2) showed no consistency at all., Conclusion(s): These results indicate that serum AMH represents the best endocrine marker to assess the age-related decline of reproductive capacity.

Objective: Age at menopause and age at the start of the preceding period of cycle irregularity (menopausal transition) show considerable individual variation. In this study we explored several markers for their ability to predict the occurrence of the transition to menopause., Design: A group of 81 normal women between 25 and 46 years of age visited the clinic two times (at T1 and T2) with an average interval of 4 years. All had a regular menstrual cycle pattern at T1. At T1, anti-mullerian hormone (AMH), follicle-stimulating hormone (FSH), inhibin B and estradiol (E2) were measured, and an antral follicle count (AFC) was made during the early follicular phase. At T2, information regarding cycle length and variability was obtained. Menopause transition was defined as a mean cycle length of less than 21 days or more than 35 days or as a mean cycle length of 21 to 35 days, but with the next cycle not predictable within 7 days during the last half year. A logistic regression analysis was performed, with the outcome measure as menopause transition. The area under the receiver operating curve (ROCAUC) was calculated as a measure of predictive accuracy., Results: In 14 volunteers, the cycle had become irregular at T2. Compared with women with a regular cycle at T2, these women were significantly older (median 44.7 vs 39.8 y, P < 0.001) and differed significantly in AFC, AMH, FSH, and inhibin B levels assessed at T1. All parameters with the exception of E2 were significantly associated with the occurrence of cycle irregularity; AMH, AFC, and age had the highest predictive accuracy (ROCAUC 0.87, 0.80, and 0.82, respectively). After adjusting for age, only AMH and inhibin B were significantly associated with cycle irregularity. Inclusion of inhibin B and age to AMH in a multivariable model improved the predictive accuracy (ROCAUC 0.92)., Conclusions: The novel marker AMH is a promising predictor for the occurrence of menopausal transition within 4 years. Adding inhibin B improved the prediction. Therefore, AMH alone or in combination with inhibin B may well prove a useful indicator for the reproductive status of an individual woman.

Background: Anti-Müllerian hormone (AMH), produced by growing pre-antral and early antral ovarian follicles, has been shown to be a useful marker for ovarian ageing. Serum AMH concentrations are elevated during reproductive life in anovulatory women, especially in those patients exhibiting polycystic ovaries (PCO). The current study was designed to investigate whether the decrease in AMH serum concentrations over time is different comparing women with normogonadotrophic anovulation [World Health Organization (WHO) group 2 (including polycystic ovary syndrome (PCOS)] and normo-ovulatory controls., Methods and Results: AMH serum levels were assessed on two occasions in 98 patients suffering from WHO 2 anovulatory infertility as well as in 41 normo-ovulatory premenopausal women. Median time interval between both visits was 2.6 years (range 0.3-9.0) for WHO 2 patients compared with 1.6 years (range 1.0-7.3) in controls. Serum AMH concentrations were significantly (P < 0.0001) elevated on both occasions in WHO 2 patients (AMH1, median = 7.5 microg/l, range 0.1-35.8; and AMH2, median = 6.7 microg/l, range 0.0-30.6) compared with controls (AMH1, median = 2.1 microg/l, range 0.1-7.4; and AMH2, median = 1.3 microg/l, range 0.0-5.0). Regression analysis, corrected for age, indicated a significant relative decrease in serum AMH concentrations over time for both groups (P < 0.001). However, the decline in serum AMH in WHO 2 patients was significantly less compared with controls (P = 0.03)., Conclusion: The present longitudinal study shows that serum AMH concentrations decrease over time both in women presenting with WHO 2 anovulatory infertility and in normo-ovulatory controls. The decrease in WHO 2 patients is less pronounced despite distinctly elevated concentrations. This observation may suggest retarded ovarian ageing and hence a sustained reproductive life span in these patients.

Anti-Müllerian hormone (AMH) is a member of the transforming growth factor-beta superfamily, which plays an important role in both ovarian primordial follicle recruitment and dominant follicle selection in mice. However, the role of AMH in folliculogenesis in humans has not been investigated in detail. In the present study, AMH expression was assessed using immunohistochemistry in ovarian sections, obtained from healthy regularly cycling women. To this end, a novel monoclonal antibody to human AMH was developed. AMH expression was not observed in primordial follicles, whereas 74% of the primary follicles showed at least a weak signal in the granulosa cells. The highest level of AMH expression was present in the granulosa cells of secondary, preantral and small antral follicles

Anti-Müllerian hormone (AMH) is expressed after birth in the ovary in the granulosa cells of healthy, small growing follicles. We have shown that AMH affects two important regulatory steps during folliculogenesis. At initial recruitment, AMH inhibits recruitment of primordial follicles into the growing pool, while at cyclic recruitment AMH lowers the FSH-sensitivity of follicles. In these ways, AMH plays an important role in regulation of ovarian follicle growth. AMH serum level is a strong candidate marker for ovarian reserve in women. In normo-ovulatory women, AMH serum levels correlated strongly with the number of antral follicles. In addition, AMH is a strong predictor for the number of oocytes retrieved in patients undergoing IVF treatment. The convenience of determination and its relative stable expression during the menstrual cycle indicate that further validation of the use of serum AMH is recommended as a clinical measure of ovarian reserve.

Mouse knockout studies have indicated that Insl3 is involved in development of the gubernaculum in males, which is essential for normal testicular descent. To determine further the functions of Insl3 we have generated transgenic (TG) mice ubiquitously expressing Insl3. In these mice low levels of transgenic Insl3 mRNA are expressed in all tissues analyzed. In the TG females the ovaries descend to the base of the abdominal cavity during the fetal period, as a consequence of the formation of male-like gubernaculum structures. Furthermore, the gubernacular structures developed express androgen receptor, identically to the corresponding structures in males. At adult age the ligaments formed connect the uterine horns to the inguinal region of the abdomen. Ligaments are also formed between the lower and upper parts of the uterine horns, and these ligaments force the uterus to form a coiled structure. However, the TG females retain their reproductive functions, indicating that neither the location of the ovaries nor the macroscopic structure of the uterus is vital for reproduction. In addition, Insl3 expression causes inguinal hernia in females, suggesting that a combination of estrogen and Insl3 action disrupts proper development of the muscular and connective tissue structures of the abdomen. The lack of a phenotype in other tissues indicates that gubernaculum formation is the most sensitive biological response as regards Insl3.

Anti-Müllerian hormone (AMH), also known as Müllerian inhibiting substance, is a member of the transforming growth factor beta superfamily of growth and differentiation factors. In contrast to other members of the family, which exert a broad range of functions in multiple tissues, the principal function of AMH is to induce regression of the Müllerian ducts during male sex differentiation. However, the patterns of expression of AMH and its type II receptor in the postnatal ovary indicate that AMH may play an important role in ovarian folliculogenesis. This review describes several in vivo and in vitro studies showing that AMH participates in two critical selection points of follicle development: it inhibits the recruitment of primordial follicles into the pool of growing follicles and also decreases the responsiveness of growing follicles to FSH.

In this article the role of LH receptor gene mutations in patients with aberrant sex differentiation is discussed. In a dominant autosomal familial form of precocious puberty in boys (familial male-limited precocious puberty) LH receptor gene mutations have been identified. These single amino acid changes, mostly found in the sixth transmembrane helix and the third intracellular loop of the transmembrane domain of the LH receptor, cause constitutive activation of LH receptor protein without the hormone present, resulting in precocious production of testosterone by the testicular Leydig cells. The large number of activating LH receptor mutations have allowed more precise molecular modeling of the LH receptor protein. In a rare hereditary form of 46,XY male pseudohermaphroditism known as Leydig cell hypoplasia, LH receptor gene mutations have been identified that completely or partially inactivate the LH receptor protein. Large gene deletions cause complete absence of the LH receptor protein, whereas other, more subtle missense mutations prevent the receptor from assuming an active conformation.

Objective: To investigate whether serum concentrations of antimüllerian hormone may be used as a marker for ovarian aging., Design: Longitudinal observational study., Setting: Academic research center., Patients: Forty-one normo-ovulatory premenopausal women and 13 healthy postmenopausal women., Main Outcome Measure(s): Concentrations of serum antimüllerian hormone (assessed on two occasions 2.6 +/- 1.7 years apart), FSH, inhibin B, and estradiol and number of ovarian follicles on ultrasonography., Result(s): Concentrations of antimüllerian hormone decreased significantly over time (median value, 2.1 microg/L [range, 0.1-7.4 microg/L] at visit 1 vs. 1.3 microg/L [range, 0.0-5.0 microg/L] at visit 2), whereas the number of antral follicles and levels of FSH and inhibin B did not change. During visits 1 and 2, concentrations of antimüllerian hormone correlated with age (r = -.40, P=.01 and r = -.57, P<.001, respectively); number of antral follicles (r =.66, P<.001 and r =.71, P<.001); and, to a lesser extent, with FSH level (r = -.29, P=.07 and r = -.37, P<.05) but not with inhibin B levels., Conclusion(s): Serum concentrations of antimüllerian hormone decreased over time in young normo-ovulatory women, whereas other markers associated with ovarian aging did not change. Concentrations of antimüllerian hormone correlate with the number of antral follicles and age and less strongly with FSH level. Concentrations of antimüllerian hormone may be a novel marker for ovarian aging.