Despite extensive research, the mechanisms by which stress affects reproduction are unknown. Activation of stress systems could potentially influence reproduction at any level of the hypothalamo-pituitary gonadal axis. Nonetheless, the predominant impact is on the secretion of gonadotrophin releasing hormone (GnRH) from the brain and the secretion of the gonadotrophins, luteinizing hormone (LH) and follicle stimulating hormone (FSH), from the gonadotrophs of the anterior pituitary gland. When stress is prolonged, it is likely that secretion of the gonadotrophins will be suppressed but the effects of acute stress or repeated acute stress are not clear. Different stressors activate different pathways for varying durations, and the actions of stress vary with sex and are influenced by the predominance of particular sex steroids in the circulation. The mechanisms by which stress influences reproduction are likely to involve complex interactions between a number of central and peripheral pathways and may be different in males and females. To understand these mechanisms, it is important to determine the stress pathways that are activated by particular stressors and to establish how these pathways affect the secretion and actions of GnRH. Furthermore, there is a need to know how stress influences the feedback actions of gonadal steroids and inhibin.

OBJECTIVE

The purpose of this study was to describe hematopoietic and reproductive hazards of Korean electronic workers exposed to solvents containing 2-bromopropane.

METHODS

Detailed medical and occupational histories were taken and thorough physical examinations with clinical laboratory tests were done for 33 workers (8 men and 25 women). Previous and present exposure was investigated in detail by industrial hygienists.

RESULTS

Of the 25 female workers, 16 were shown to have secondary amenorrhea with high follicle-stimulating hormone levels, normal prolactin levels, and hot flashes. A total of eight workers with amenorrhea concurrently showed findings of pancytopenia. Among eight male workers, two showed azoospermia and another four showed some degree of oligospermia (normal>> 20 million. ml-1) or reduced sperm motility (normal>> 50%). The bone marrow effects and the testis or ovarian failure was shown to be the main health hazards in this workplace. Except for the cleaning solution containing 97.4% 2-bromopropane, no other known physical or chemical agents could be identified as responsible for the gonadal and bone marrow effects, including ionizing radiation, lead, ethylene glycol ether and its acetates, benzene, and dibromochloropropane.

CONCLUSIONS

No previous studies have reported human toxicity for 2-bromopropane, but the results of this study lead to the tentative conclusion that the causal agent for the gonadal and bone marrow effects among the workers might be 2-bromopropane.

Sixteen nondiabetic women with polycystic ovary syndrome (PCOS) aged 18 to 33 years were studied before and after 8 weeks on metformin (1.5 g/d) therapy to assess whether reducing hyperinsulinemia would reduce the levels of the major inhibitor of fibrinolysis, antigenic plasminogen activator inhibitor type 1 (PAI-1). Compared with six normal control women, PCOS women had a higher body mass index (BMI), waist to hip ratio, fasting insulin (Izero), insulin area under the curve during oral glucose tolerance testing (IA), glucose area under the curve during oral glucose tolerance testing (GA), IA/GA ratio, PAI-1, luteinizing hormone (LH) and ratio of LH to follicle-stimulating hormone (FSH), and free testosterone, and lower high-density lipoprotein (HDL) cholesterol (all P < .025). On metformin, BMI decreased 1.3% (P = .04), Izero 43% (P = .002), IA 31% (P = .03), GA 11% (P = .02), PAI-1 16% (P = .01), lipoprotein(a) [Lp(a)] 42% (P = .004), free testosterone 46% (P = .0006), LH 44% (P = .004), and the LH/FSH ratio 41% (P = .0001). On metformin, absolute and percent reductions in Izero correlated with absolute and percent reductions in PAI-1 (r = .60, P = .015 and r = .64, P = .008). On metformin, by stepwise multiple regression, the absolute reduction in Izero was a significant determinant of the absolute reduction in PAI-1 (partial R2 = 35%, P = .02), and the percent reduction in Izero was a significant determinant of the percent reduction in PAI-1 (partial R2 = 52%, P = .003). Metformin decreases Izero in hyperinsulinemic PCOS patients, reverses the hyperinsulinemia-driven endocrinopathy, decreases PAI-1, and decreases Lp(a), and should thus reduce the increased risk of atherothrombosis in PCOS.

The interaction of the testis and gonadotropin secretion was studied in 15 men surviving chemotherapy for lymphoma. Azoospermia and complete destruction of all testicular germinal elements were present in 10 of the 15 men; however, Sertoli cells and Leydig cells were present. In these 10 men plasma follicle-stimulating hormone (FSH) levels were fourfold higher than in normal men of similar age whereas luteinizing hormone (LH) levels were normal. In contrast, both FSH and LH were normal in the remaining five men. Three had a full complement of spermatogenic tissue on biopsy and normal sperm concentrations. The other two men were azoospermic; one demonstrated full spermatogenesis in 30% of his tubules; the other had only a few spermatogonia in all tubules. In those patients with lower levels of gonadotropins pituitary insufficiency was excluded by the demonstration of appropriate responsiveness of FSH and LH to clomiphene administration. Similarly, Leydig cell function was normal since plasma testosterone was within the normal range in 13 of the 15 men and only slightly decreased in two. Thus, following chemotherapy, testicular damage was restricted to the germinal tissue, and this in turn was associated with a selective increase in FSH. The source of the FSH inhibitor is either the Sertoli cell or early germinal elements. However, since FSH levels are only half as high as those reported for castrate men, other testicular factors may modify FSH secretion.

There is experimental evidence of adverse effects of endosulfan on the male reproductive system, but there are no human data. Therefore, we undertook a study to examine the relationship between environmental endosulfan exposure and reproductive development in male children and adolescents. The study population was composed of 117 male schoolchildren (10-19 years of age) of a village situated at the foothills of cashew plantations, where endosulfan had been aerially sprayed for more than 20 years, and 90 comparable controls with no such exposure history. The study parameters included recording of clinical history, physical examination, sexual maturity rating (SMR) according to Tanner stages, and estimation of serum levels of testosterone, luteinizing hormone (LH), follicle-stimulating hormone, and endosulfan residues (70 study and 47 control subjects). Mean +/- SE serum endosulfan levels in the study group (7.47 +/- 1.19 ppb) were significantly higher (p < 0.001) than in controls (1.37 +/- 0.40 ppb). Multiple regression analysis showed that SMR scoring for development of pubic hair, testes, penis, and serum testosterone level was positively related to age and negatively related to aerial exposure to endosulfan (AEE; p < 0.01). Serum LH levels were significantly positively related to AEE after controlling for age (p < 0.01). The prevalence of congenital abnormalities related to testicular descent (congenital hydrocele, undescended testis, and congenital inguinal hernia) among study and controls subjects was 5.1% and 1.1%, respectively, but the differences were statistically nonsignificant. Our study results suggest that endosulfan exposure in male children may delay sexual maturity and interfere with sex hormone synthesis. Our study is limited by small sample size and nonparticipation.

BACKGROUND

Polycystic ovary syndrome (PCOS) is often characterized by chronic oligo- or anovulation (usually manifested as oligo- or amenorrhea), and hyperandrogenism. In addition, 30-40% of PCOS women have impaired glucose tolerance, and a defect in the insulin signaling pathway (inositol-containing phosphoglycan mediators) seems to be implicated in the pathogenesis of insulin resistance. PCOS patients are subfertile as a consequence of such ovulatory disorders and often need drugs, such as clomiphene citrate or follicle-stimulating hormone, for ovulation induction, which increases the risk of multiple pregnancy and ovarian hyperstimulation syndrome. We hypothesized that the administration of an isoform of inositol (myo-inositol), belonging to the vitamin B complex, would improve the insulin-receptor activity, restoring normal ovulatory function.

METHODS

Twenty-five PCOS women of childbearing age with oligo- or amenorrhea were enrolled in the study. Ovulatory disorder due to PCOS was apparently the only cause of infertility; no tubal defect or deficiency of male semen parameters was found. Myo-inositol combined with folic acid (Inofolic) 2 g twice a day was administered continuously. During an observation period of 6 months, ovulatory activity was monitored with ultrasound scan and hormonal profile, and the numbers of spontaneous menstrual cycles and eventually pregnancies were assessed.

RESULTS

Twenty-two out of the 25 (88%) patients restored at least one spontaneous menstrual cycle during treatment, of whom 18 (72%) maintained normal ovulatory activity during the follow-up period. A total of 10 singleton pregnancies (40% of patients) were obtained. Nine clinical pregnancies were assessed with fetal heart beat at ultrasound scan. Two pregnancies evolved in spontaneous abortion.

CONCLUSIONS

Myo-inositol is a simple and safe treatment that is capable of restoring spontaneous ovarian activity and consequently fertility in most patients with PCOS. This therapy did not cause multiple pregnancy.

To test the hypothesis that estradiol, inhibin A, and inhibin B contribute differentially to FSH negative feedback in specific phases of the menstrual cycle, daily blood samples were obtained across a control cycle and after selective estrogen blockade with tamoxifen. To examine the site of estradiol-negative feedback in control and tamoxifen treatment cycles, early follicular phase GnRH (free alpha-subunit) pulse frequency was assessed in normal women, and FSH levels were examined in GnRH-deficient women in whom hypothalamic output was fixed with GnRH administration. FSH was higher in the early follicular phase in the presence of estrogen receptor blockade (15.7 +/- 3.1 vs. 13.2 +/- 1.9 IU/liter; P < 0.05) but was not increased in the late follicular phase. In the luteal phase, FSH was elevated (10.1 +/- 0.7 vs. 7.3 +/- 0.6 IU/liter; P < 0.01). In normal women, free alpha-subunit pulse frequency increased (7.3 +/- 0.4 vs. 4.8 +/- 0.4 pulses per 8 h; P < 0.003), but in GnRH-deficient women, there was no FSH increase (11.1 +/- 1.6 vs. 12.5 +/- 3.6 IU/liter) in the early follicular phase in the presence of estrogen blockade. In conclusion, estradiol exerts a greater role over inhibin in FSH-negative feedback regulation during the luteal phase and the luteal-follicular transition. In contrast, inhibin A and/or B plays a more critical role as the follicular phase progresses. In addition, these studies support a primary if not exclusive hypothalamic site of estrogen-negative feedback in the early follicular phase.

OBJECTIVE

The aim of this study was to estimate the probabilities and identify risk factors for entering the menopausal transition and moving into each subsequent transition stage.

METHODS

Estimations of probabilities of entry into each menopausal transition stage and predictors associated with each transition stage were conducted in a population-based cohort of midlife women.

RESULTS

The likelihood of entering the menopausal transition and moving into each subsequent stage was increased for each unit increase in follicle-stimulating hormone (FSH) (P < 0.001) and with each unit decrease in inhibin B (P < 0.001) in the adjusted multivariable model. The largest observed change in average FSH levels was the comparison of women in the late transition (stage 4), with an average of 24.78 mIU/mL, to those in the early transition (stage 3), with 10.38 mIU/mL. Women experiencing this amount of change in FSH had an odds of transitioning from stages 3 to 4 of 1.90 (95% CI, 1.86-1.95). Decreases in inhibin B resulted in odds ratios similar to the magnitude of changes in FSH. Current smoking increased the odds of transition into each stage by approximately 30% (odds ratio, 1.30; 95% CI, 1.28-1.32). Average estradiol levels did not change dramatically between stages. However, higher estradiol significantly increased the odds of entering the transition (P = 0.013). Age and race predicted transitions into some but not all stages. Body mass index, alcohol use, and age at menarche did not predict entrance into any stage of the menopausal transition after adjusting for other study variables.

CONCLUSIONS

These results show that increased FSH, decreased inhibin B, and smoking strongly predict entry into the earliest stages of the menopausal transition as defined by changes in bleeding patterns. African Americans entered the transition before white women, but race did not predict entry into late transition stages. Higher estradiol levels predict entry into the earliest transition stage but not subsequent stages.

We have investigated the hypothesis that hyperinsulinemia may cause the polycystic ovary syndrome (PCO) by directly stimulating gonadal steroidogenesis and/or gonadotropin secretion. 10 insulin-resistant women with PCO and 5 age- and weight-matched ovulatory normal women had pulsatile gonadotropin release, gonadotrope sensitivity to gonadotropin-releasing hormone, and sex hormone levels studied on two consecutive study days, basally and during the infusion of insulin (mean +/- SEM steady state insulin levels, 1,254 +/- 63 microU/ml PCO vs. 907 +/- 92 microU/ml normal, P less than or equal to 0.01). Insulin acutely increased mean delta (6 h minus prestudy) levels of androstenedione (A) (P less than or equal to 0.001) and estradiol (E2) (P less than or equal to 0.05) and decreased mean plasma pool (0-6 h) levels of testosterone (T) (P less than 0.05), nonsex hormone binding globulin-bound T (P less than 0.05), and dihydrotestosterone (P less than or equal to 0.01) in the PCO women. Insulin also decreased mean plasma 6 h A to estrone (E1) ratios and increased 6 h E1 levels (both P less than or equal to 0.05) in the PCO women. There were significant sequence effects (insulin + day) in the PCO women on T/E2 ratios, indicating a carryover action of insulin. Insulin had no effects on gonadotropin release in the PCO women. In the normal women, the only significant change was an insulin or study day effect that increased mean 6 h E2 levels (P less than or equal to 0.01). There were significant spontaneous decreases in mean luteinizing hormone (p less than 0.05) and follicle-stimulating hormone levels (p less than or equal to 0.01) in the PCO but not the normal women on the second day of study. This study indicates that insulin can directly alter peripheral sex hormone levels independent of changes in gonadotropin release in insulin-resistent PCO women. Insulin decreased the levels of potent androgens in PCO women and did not increase androgen levels in normal women, arguing against a simple, direct causal relationship between hyperinsulinemia and hyperandrogenism in PCO.

The thyrotropin (TSH) receptor belongs to a subfamily of G protein-coupled receptors, which also includes luteinizing hormone and follicle-stimulating hormone receptors. The TSH receptor (TSHR) differs from the latter by the presence of an additional specific segment in the C-terminal part of its ectodomain. We show here that this insertion is excised in the majority of receptor molecules. Preparation of specific monoclonal antibodies to this region, microsequencing, enzyme-linked immunosorbent assay, and immunoblot studies have provided insight into the mechanisms of this excision. In the human thyroid gland, N termini of the transmembrane receptor beta subunit were found to be phenylalanine 366 and leucines 370 and 378. In transfected L cells a variety of other more proximal N termini were found, probably corresponding to incomplete excisions. The most extreme N terminus was observed to lie at Ser-314. These observations suggest that after initial cleavage at Ser-314 the inserted fragment of TSHR is progressively clipped out by a series of cleavage reactions progressing up to amino acids 366-378. The impossibility of recovering the excised fragment from purified receptor, cell membranes, or culture medium supports this interpretation. The cleavage enzyme has previously been shown to be inhibited by BB-2116, an inhibitor of matrix metalloproteases. However, we show here that it is unaffected by tissue inhibitors of metalloproteases. The cleavage enzyme is very similar to TACE (tumor necrosis factor alpha-converting enzyme) in both these characteristics. However, incubation of the TSH receptor with the purified recombinant catalytic domain of TACE, co-transfection of cells with TACE and TSHR expression vectors, and the use of mutated Chinese hamster ovary cells in which TACE is inactive suggested that the TSHR cleavage enzyme is different from TACE. TACE and TSHR cleavage enzyme may thus possibly be related but different members of the adamalysin family of metzincin metalloproteases.

A double-lind crossover study involving 16 hypogonadal women compared the effects of placebo and conjugated estrogens, 0.625 mg daily, on gonadotropin levels, symptoms, sleep patterns, and psychological state. After one month, serum concentrations of follicle-stimulating hormone fell 31%, and levels of luteinizing hormone, 19%; the number of vasomotor flushes also decreased. The administration of estrogens was also associated with a shorter mean sleep latency, a longer period of rapid eye movement sleep, and a positive correlation between psychological intactness (as clinically ranked) and latency to sleep onset. Psychological testing, including the Clyde Mood Scale, and the Gottschalk-Gleser Test indicated that estrogens caused this group to be less outwardly aggressive but more inwardly hostile.

The human (h) follicle-stimulating hormone receptor (FSHR) belongs to the superfamily of G protein-coupled receptors (GPCRs). This receptor consists of 695 amino acid residues and is preferentially coupled to the G(s) protein. This receptor is highly conserved among species (overall homology, 85%), with a 25-69% homology drop when compared to the human LH and TSH receptors. Although studies in prototypical rhodopsin/beta-adrenergic receptors suggest that multiple domains in the intracellular loops (iL) and the carboxyl-terminus (Ctail) of these receptors contribute to G protein coupling and receptor expression, there is a paucity of structure/function data on the role of these domains in FSHR function. Employing point mutations we have found that several residues present in the iL2 of the hFSHR are important for both coupling the receptor to the G(s) protein and maintaining the receptor molecule in an inactive conformation. In fact, HEK-293 cells expressing several hFSHR mutants with substitutions at R(450) (central to the highly conserved ERW triplet motif) and T(453) (a potential target for phosphorylation) failed to mediate ligand-provoked G(s) protein activation but not agonist binding, whereas substitutions at the hydrophobic L(460) (a conserved residue present in all glycoprotein hormone receptors) conferred elevated basal cAMP to the transfected cells. Thus, this particular loop apparently acts as a conformational switch for allowing the receptor to adopt an active conformation upon agonist stimulation. Residues in both ends of the iL3 are important for signal transduction in a number of GPCRs, including the FSHR. We have recently explored the importance of the reversed BBXXB motif (BXXBB; where B represents a basic residue and X a non-basic residue) present in the juxtamembrane region of the hFSHR iL3. A hFSHR mutant with all basic amino acids present in the iL3 BXXBB motif replaced by alanine failed to bind agonist and activate effector, and was expressed as an immature < or =62kDa form of the receptor. Individual substitutions of basic residues resulted in mutants that bound agonist normally but failed to activate effector when replaced at R(552) or R(556). Triple mutations in the same motif located in the NH(2)-end of the Ctail resulted in a complete inability of the receptor to bind agonist and activate effector, whereas individual substitutions resulted in decreased or virtually abolished agonist binding and cAMP accumulation, with both functions correlating with the detected levels of mature (80kDa) forms of the receptor. Thus, the BXXBB motif at the iL3 of the FSHR is essential for coupling the activated receptor to the G(s) protein, whereas the same motif in the Ctail is apparently more important for membrane expression. The role of cysteine residues present in the Ctail of the FSHR is an enigma since there are no conserved cysteines amongst LHR, FSHR and TSHR. C(629) and C(655) are conserved in the gonadotropin receptors but not in the TSHR. Alanine replacement of C(627) had no effect on hFSHR expression and function, whereas the same mutation at C(629) altered membrane expression and signal transduction. Serine or threonine substitutions of C(655) did not modify any of the parameters analyzed. In the hFSHR, C(629) may be a target for palmitoylation, and apparently it is the only cysteine residue in the Ctail domain that might play an important role in receptor function.

Concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), progesterone (P), 17 alpha-hydroxyprogesterone (17 alpha OHP), 17 beta-estradiol (E2), and prolactin (HPr) were monitored for one complete menstrual cycle in teenage swimmers, a gynecologically age-matched control group, and a group of fertile adult women. The swimmers experienced anovulatory menstrual cycles. The time from the LH surge to the onset of menses ("luteal" phase) was very short in the swimmers (4.5 +/- 0.6 days) in comparison with the lengths of these phases in the adults (13.4 +/- 1.7 days; P less than 0.05) and in the control group (7.8 +/- 3.0 days; P less than 0.05). In the follicular phase the swimmers' LH concentration was elevated and their FSH concentration was depressed in comparison with each of the other groups (P less than 0.05). Luteal phase FHS, P, E2, and 17 alpha OHP were also lower in the swimmers (P less than 0.05), as was HPr (0.05 greater than P less than 0.10). Gonadotropin concentrations and luteal phase P concentrations were not different (P greater than 0.05) in the adults and the control group. The present findings indicate that the corpora lutea in the swimmers were not functioning properly. It is likely that the swimmers' strenuous daily 2-4 h training regimen is implicated.

To study the role of extracellular nucleotides in the regulation of Sertoli cells, the effects of ATP and its analogs on the Ca(2+)-phospholipid- and cAMP-dependent pathways were tested. Cultured Sertoli cells from immature animals were incubated with ATP or structurally related compounds, and phosphoinositide (PI) turnover or cAMP accumulation was measured. Among the several nucleotide phosphate analogs tested, adenosine 5'-O-(3-thiotriphosphate) was the agonist most potent in stimulating inositol phosphate accumulation. The effects of purine nucleotides on PI turnover were time and concentration dependent. Because nonhydrolizable ATP analogs also stimulated PI turnover, ATP metabolites or metabolic products are not responsible for the observed stimulation. The order of potency of the different ATP analogs [adenosine 5'-O-(3-thiotriphosphate)>> ATP approximately equal to UTP>> beta, gamma-methyleneadenosine 5'-triphosphate, 2-methylthio-ATP>> adenosine] was consistent with the presence of P2U receptors (nucleotide receptors) on the surface of the Sertoli cell. Augmented PI turnover was accompanied by a transient increase in Ca2+ concentration, measured in single Sertoli cells loaded with the intracellular Ca2+ indicator fura-2. When used alone, ATP and its analogs did not have a direct effect on cAMP levels in the Sertoli cell. However, ATP or its analogs inhibited FSH-dependent cAMP accumulation by more than 70%. Purine nucleotides also efficiently blocked the effects of FSH distal to cAMP accumulation, because extracellular ATP completely reversed the changes in Sertoli cell shape induced by FSH. The nucleotide-dependent inhibition of cAMP accumulation was blocked by pertussis toxin to a different degree depending on the purine or pirimidine nucleotide used. This indicated that more than one mechanism contributes to the purine nucleotide-dependent inhibition of cAMP accumulation. These data provide evidence that purine nucleotide receptors coupled to multiple pathways are present on the Sertoli cell in culture, and that extracellular ATP has profound biological effects on the FSH responsiveness of the Sertoli cell.

Changes in the endocrinology of the pituitary-ovarian axis first become manifest at about the age of 40, a selective rise in serum follicle stimulating hormone (FSH) levels occurring at about the same time as a marked acceleration in the loss of primordial follicles from the ovary. FSH levels gradually increase with increasing age in women who continue to cycle regularly. During the menopausal transition, initiated when changes in cycle frequency or in menstrual flow are first observed, both gonadotrophins, oestradiol and inhibin show a marked degree of variability with abrupt changes from typical post-menopausal patterns to those characteristic of the reproductive age group. Within 1-2 years after the final menstrual period or menopause, FSH levels are markedly elevated, luteinizing hormone (LH) levels moderately so, while oestradiol and inhibin levels are low or undetectable. Post-menopausally, adrenal androstenedione is the major source of oestrogen and serum testosterone levels fall moderately, with oophorectomy leading to a further significant fall. Serum sex hormone binding globulin levels fall to a small degree post-menopausally. Areas of persisting controversy include the question of whether oestradiol levels fall with increasing age prior to the onset of the menopausal transition, the relative roles of oestradiol and inhibin in the selective rise of serum FSH and the role of serum androgens post-menopausally.

The present clinical study examines the neuroregulatory hypothesis that feedback restraint of LH and FSH secretion by testosterone requires in vivo aromatization. To test this postulate, we prospectively and randomly assigned 47 healthy young men to 1 of 5 parallel short-term (5-day) double-blind interventions with: 1) placebo; 2) high-dose ketoconazole (KTCZ, 400 mg orally 4 times daily) to block both Leydig-cell and adrenal steroidogenesis; 3) KTCZ and transdermal testosterone delivery (7.5 mg daily); 4) KTCZ and transdermal estradiol (0.05 mg daily); or 5) KTCZ, testosterone, and the selective and potent aromatase inhibitor, anastrazole (5 mg orally twice daily). Blood was sampled every 10 min for 27 h on the last day of intervention to quantitate 24-h mean spontaneous and 3-h post-GnRH-stimulated (100 ng/kg iv bolus) LH and FSH release. KTCZ administration lowered the serum total testosterone concentration markedly from (mean +/- SEM) 423 +/- 57 ng/dL (15 +/- 2.0 nmo/L) during placebo ingestion to 58 +/- 8.6 ng/dL (2.0 +/- 0.3 nmol/L) (P < 10(-3)). Transdermal androgen addback along with KTCZ blockade increased testosterone levels to 607 +/- 57 ng/dL (21 +/- 2.0 nmol/L). KTCZ exposure alone drove a 3-fold increase in serum LH concentrations (P < 10(-3)) and a 2.5-fold rise in FSH secretion (P = 0.015), as assessed by high-specificity immunoradiometric assays. Concomitant transdermal testosterone (or estradiol) delivery repressed the elevated secretion of both LH and FSH to mid-normal baseline values. A 3-fold administration of anastrazole, KTCZ, and testosterone completely opposed exogenous testosterone's suppression of 24-h LH and FSH secretion. Anastrazole coadministration likewise abolished testosterone-dependent inhibition of 3-h GnRH-stimulated LH and FSH release. In summary, assuming the specificity of anastrazole's inhibition of aromatase activity, we conclude that circulating testosterone in healthy men curtails endogenously driven as well as exogenous GnRH-stimulated LH and FSH secretion conditional on its in vivo aromatization.

Fragile X syndrome is the most common inherited form of mental retardation, affecting approximately 1 in 4,000 males and 1 in 8,000 females. DNA-based molecular analysis is the preferred method of diagnosis for fragile X syndrome and its premutations. Prenatal testing for fragile X syndrome should be offered to known carriers of the premutation or mutation. Testing for fragile X syndrome should be considered for any child with developmental delay of uncertain etiology, autism, or autistic behavior or for any individual with mental retardation of uncertain etiology. Women with ovarian failure or an elevated follicle-stimulating hormone level before 40 years of age without a known cause should be screened to determine whether they have the fragile X premutation.

Expansion of the cumulus cell-oocyte complex (COC) in the preovulatory mammalian follicle requires a transient induction of hyaluronan (HA) synthesis by the cumulus cells. We studied the interactions of known factors that regulate this process by isolating compact COCs from mice and inducing their expansion in vitro. Maximum HA synthesis requires either follicle-stimulating hormone (FSH) or epidermal growth factor (EGF) in combination with either a soluble factor(s) produced by the oocyte or transforming growth factor beta1. FSH (or EGF) exerts its effects during the first 2 h of incubation, before HA synthesis actually begins. The oocyte factor(s) (or transforming growth factor beta1) exerts its effects from 2 h onwards and must be continuously present throughout the subsequent approximately 10 h to achieve a maximum level of HA synthesis. FSH stimulates intracellular cAMP synthesis, which correlates with net HA production up to approximately 14 fmol/COC at 5 ng/ml FSH; however, higher concentrations of FSH increase cAMP levels approximately 10-fold higher with no additional effect on HA synthesis. EGF at saturating concentrations for HA synthesis does not stimulate cAMP above basal levels. Tyrosine kinase inhibitors genistein and tyrphostin AG18 nearly abolish the HA synthesis response to EGF and inhibit the response to FSH by approximately 60%, suggesting that a tyrosine kinase activity is involved for both factors, whereas FSH also operates partially through another signaling pathway. Actinomycin D abolishes HA synthesis if added at the beginning of culture and reduces HA synthesis by approximately 50% if added between 6-12 h when HA synthesis is normally maximal. The results suggest that regulation of HA synthesis is primarily controlled at the transcriptional level.

Gonadotropin-releasing hormone (GnRH) acts via 7 transmembrane region receptors on gonadotrophs to stimulate synthesis and secretion of the luteinizing hormone and follicle-stimulating hormone. It is secreted in pulses, and its effects depend on pulse frequency, but decoding mechanisms are unknown. Here we have used (nuclear factor of activated T-cells 2 (NFAT2)-emerald fluorescent protein) to monitor GnRH signaling. Increasing [Ca(2+)](i) causes calmodulin/calcineurin-dependent nuclear NFAT translocation, a response involving proteins (calmodulins and NFATs) that decode frequency in other systems. Using live cell imaging, pulsatile GnRH caused dose- and frequency-dependent increases in nuclear NFAT2-emerald fluorescent protein, and at low frequency, translocation simply tracked GnRH exposure (albeit with slower kinetics). At high frequency (30-min intervals), failure to return to basal conditions before repeat stimulation caused integrative tracking, illustrating how the relative dynamics of up- and downstream signals can increase efficiency of GnRH action. Mathematical modeling predicted desensitization of GnRH effects on [Ca(2+)](i) and that desensitization would increase with dose, frequency, and receptor number, but no such desensitization was seen in HeLa and/or LbetaT2 cells possibly because pulsatile GnRH did not reduce receptor expression (measured by immunofluorescence). GnRH also caused dose- and frequency-dependent activation of alphaGSU, luteinizing hormone beta, and follicle-stimulating hormone beta luciferase reporters, effects that were blocked by calcineurin inhibition. Pulsatile GnRH also activated an NFAT-responsive luciferase reporter, but this response was directly related to cumulative pulse duration. This together with the lack of desensitization of translocation responses suggests that NFAT may mediate GnRH action but is not a genuine decoder of GnRH pulse frequency.

The effects of 30 min of exercise (74.1 +/- 3.0% (VO2), on the responses of progesterone (P), estradiol (E2), follicle stimulating hormone (FSH), and luteinizing hormone (LH) were investigated in 10 women. With such exercise significant increments occurred in P (37.6 +/- 9.5%) and E2 (13.5 +/- 7.5%) (P less than 0.05), whereas no changes were observed in FSH and LH (p greater than 0.05). Exercise in the luteal phase and during menses provoked similar changes in P, but E2 concentrations remained unchanged when exercise occurred during menses (p greater than 0.05). With 8-11 weeks of training the menstrual cycles were quite irregular and retesting of subjects in the same phase of the cycle was not possible. Yet, when subjects were retested after training, no changes occurred in P, E2 or LH (p greater than 0.05) but a decrement did occur in FSH (p less than 0.10). Thus, heavy exercise in untrained subjects provokes significant increments in ovarian hormones, whereas no such increments are observed in trained subjects exercising at the same absolute workload.

Pulsatile hypothalamic release of GnRH tightly controls reproduction by activating a specific cell membrane receptor (GnRHR) on the surface of pituitary gonadotrophs to stimulate luteinizing hormone and follicle-stimulating hormone secretion. During the last 10 years, 21 loss-of-function GNRHR mutations have been identified in patients with idiopathic hypogonadotropic hypogonadism. Although most patients with hypogonadotropic hypogonadism can be treated by delivery of exogenous pulsatile GnRH, in several cases, patients with GNRHR mutations fail to respond efficiently to GnRH treatment. The impact of each mutation on GnRHR function has been studied extensively in vitro, but correlation with clinical phenotype is not always evident. By combining recent advances into the molecular mechanisms controlling ligand binding and receptor activation with data accumulated from clinical studies, this review summarizes the overall structure-function relationships of the human GnRH receptor, with an emphasis on the impact of naturally occurring mutations. Furthermore, given that it was recently demonstrated that pharmacological chaperones can rescue altered receptor function in vitro, potential therapeutic approaches are also discussed.

The study presented characterizes the ovarian and pituitary function of the aged female macaque through a complete annual reproductive cycle to compare hormone dynamics during the human and nonhuman primate menopausal transition. Data collected over an entire year from aged macaque females indicated that urinary FSHbeta subunit baseline levels statistically significantly increased in females after age-related abnormal menstrual cycles occurred. These abnormal cycles were followed by anovulation and complete cessation of follicular activity. No statistically significant difference in urinary FSHbeta subunit levels was seen between females that exhibited year-round normal ovarian cycles and those that exhibited seasonal ovarian cycles followed by an interval of anovulation during the nonbreeding season. Basal urinary estrogen metabolite levels were not observed to decrease until ovarian cycles became abnormal and FSHbeta subunit levels began to rise. Early follicular phase circulating inhibin beta levels were statistically significantly reduced only when ovariectomized females were compared to the year-round normally cycling females. A statistically nonsignificant trend toward decreased inhibin secretion, however, was apparent in aged females with normal cycles, aged females with abnormal cycles, anovulatory aged females, and finally, ovariectomized females. Whereas decreased circulating levels of dehydroepiandrosterone sulfate showed a general decline over the 1-yr study period in all groups, they were lowest in the year-round normally cycling group, progressively higher in the normal-to-anovulatory group and abnormal-to-anovulatory group, and highest in the anovulatory group. Finally, the nonbreeding season was associated with the highest number of abnormal cycles, suggesting that onset of complete ovarian senescence in these study macaques was more likely to occur during that time (i.e., females were less likely to return to normal ovarian cycles the following breeding season and more likely to exhibit permanent ovarian quiescence).

PURPOSE We compared the endocrine effects of 6 and 12 months of adjuvant letrozole versus tamoxifen in postmenopausal patients with hormone-responsive early breast cancer within an ongoing phase III trial. PATIENTS AND METHODS Patients were randomly assigned to receive tamoxifen, letrozole, or letrozole plus zoledronic acid. Serum values of estradiol, follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, dehydroepiandrosterone-sulphate (DHEA-S), progesterone, and cortisol were measured at baseline and after 6 and 12 months of treatment. For each hormone, changes from baseline at 6 and 12 months were compared between treatment groups, and differences over time for each group were analyzed. Results Hormonal data were available for 139 postmenopausal patients with a median age of 62 years, with 43 patients assigned to tamoxifen and 96 patients assigned to letrozole alone or combined with zoledronic acid. Baseline values were similar between the two groups for all hormones. Many significant changes were observed between drugs and for each drug over time. Namely, three hormones seemed significantly affected by one drug only: estradiol that decreased and progesterone that increased with letrozole and cortisol that increased with tamoxifen. Both drugs affected FSH (decreasing with tamoxifen and slightly increasing with letrozole), LH (decreasing more with tamoxifen than with letrozole), testosterone (slightly increasing with letrozole but not enough to differ from tamoxifen), and DHEA-S (increasing with both drugs but not differently between them). Zoledronic acid did not have significant impact on hormonal levels. CONCLUSION Adjuvant letrozole and tamoxifen result in significantly distinct endocrine effects. Such differences can explain the higher efficacy of letrozole as compared with tamoxifen.

Amenorrhea can cause bone loss, but not all mechanisms in this process are known. The degree of bone loss in amenorrheic women is determined by the cause of the amenorrhea. The aim of this study was to investigate the influence of secondary amenorrhea on bone density and to compare the bone density between hypogonadotropic amenorrheic women and hypergonadotropic amenorrheic women. Twenty-two amenorrheic and 12 eumenorrheic women under the age of 40 were involved in this study. Every woman underwent measurements of lumbar spine and femoral neck bone density, body mass index (BMI), and serum levels of follicle-stimulating hormone (FSH), luteinizing hormone (LH), estradiol, progesterone, and prolactin. According to FSH levels, we divided the women with amenorrhea into two groups: hypergonadotropic (n = 7; FSH, >40 IU/l) and hypogonadotropic (n = 15; FSH, < or =40 IU/l) amenorrheic women. Amenorrheic women had a lower lumbar spine bone density than eumenorrheic controls (P = 0.002). Hypergonadotropic amenorrheic women had lower lumbar spine bone density (P = 0.026) than hypogonadotropic ameneorrheic women. In the hypergonadotropic group, only FSH level had a correlation (negative) with lumbar spine bone density (P = 0.05), but in the hypogonadotropic group, there was no correlation between hormonal levels, BMI, age, or duration of amenorrhea. BMI was positively correlated with lumbar spine bone density in amenorrheic women (P < 0.025). Amenorrheic women had lower bone density than eumenorrheic women, but hypergonadotropic amenorrheic women had lower bone density than hypogonadotropic women. The greater bone loss in the hypergonadotropic amenorrheic group could have been caused by a potential direct effect of FSH on bone metabolism.