Citations
All
Search in:AllTitleAbstractAuthor name
Publications
(21K+)
Patents
Grants
Pathways
Clinical trials
Publication
Journal: Journal of Biological Chemistry
April/18/2005
Abstract
Ovarian follicles undergo exponential growth in response to follicle-stimulating hormone (FSH), largely as a result of the proliferation of granulosa cells (GCs). In vitro under serum-free conditions, rat GCs differentiate in response to FSH but do not proliferate unless activin is also present. In the presence of FSH plus activin, GCs exhibit enhanced expression of cyclin D2 as well as inhibin-alpha, aromatase, steroidogenic factor-1 (SF-1), cholesterol side chain (SCC), and epiregulin. In this report we sought to identify the signaling pathways by which FSH and activin promote GC proliferation and differentiation. Our results show that these responses are associated with prolonged Akt phosphorylation relative to time-matched controls and are dependent on phosphatidylinositol 3-kinase (PI 3-kinase) and Smad2/3 signaling, based on the ability of the PI 3-kinase inhibitor LY294002 or infection with adenoviral dominant negative Smad3 (DN-Smad3) mutant to attenuate induction of cyclin D2, inhibin-alpha, aromatase, SCC, SF-1, and epiregulin. The DN-Smad3 mutant also abolished prolonged Akt phosphorylation stimulated by FSH plus activin 24 h post-treatment. Infection with the adenoviral constitutively active forkhead box-containing protein, O subfamily (FOXO)1 mutant suppressed induction of cyclin D2, aromatase, inhibin-alpha, SF-1, and epiregulin. Transient transfections of GCs with constitutively active FOXO1 mutant also suppressed cyclin D2, inhibin-alpha, and epiregulin promoter-reporter activities. Chromatin immunoprecipitation results demonstrate in vivo the association of FOXO1 with the cyclin D2 promoter in untreated GCs and release of FOXO1 from the cyclin D2 promoter upon addition of FSH plus activin. These results suggest that proliferation and differentiation of GCs in response to FSH plus activin requires both removal of FOXO1-dependent repression and positive signaling from Smad2/3.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
January/10/1999
Abstract
The purposes of this investigation were to evaluate the characteristics of three consecutive menstrual cycles and to determine the frequency ofluteal phase deficiency (LPD) and anovulation in a sample of sedentary and moderately exercising, regularly menstruating women. For three consecutive menstrual cycles, subjects collected daily urine samples for analysis of FSH, estrone conjugates (E1C), pregnanediol-3-glucuronide (PdG), and creatinine (Cr). Sedentary (n=11) and exercising (n=24) groups were similar in age (27.0+/-1.3 yr), weight (60.3+/-3.1 kg), gynecological age (13.8+/-1.2 yr), and menstrual cycle length (28.3+/-0.8 days). Menstrual cycles were classified by endocrine data as ovulatory, LPD, or anovulatory. No sedentary women (0%) had inconsistent menstrual cycle classifications from cycle to cycle, but 46% of the exercising women were inconsistent. The sample prevalence of LPD in the exercising women was 48%, and the 3-month sample incidence was 79%. In the sedentary women, 90% of all menstrual cycles were ovulatory (SedOvul; n=28), whereas in the exercising women only 45% were ovulatory (ExOvul; n=30); 43% were LPD (ExLPD; n=28), and 12% were anovulatory (ExAnov; n=8). In ExLPD cycles, the follicular phase was significantly longer (17.9+/-0.7 days), and the luteal phase was significantly shorter (8.2+/-0.5 days) compared to ExOvul (14.8+/-0.9 and 12.9+/-0.3 days) and SedOvul (15.9+/-0.6 and 12.9+/-0.4 days) cycles. Luteal phase PdG excretion was lower (P < 0.001) in ExLPD (2.9+/-0.3 microg/mg Cr) and ExAnov (0.8+/-0.1 microg/mg Cr) cycles compared to SedOvul cycles (5.0+/-0.4 microg/mg Cr). ExOvul cycles also had less (P < 0.01) PdG excretion during the luteal phase (3.7+/-0.3 microg/mg Cr) than the SedOvul cycles. E1C excretion during follicular phase days 2-5 was lower (P=0.05) in ExOvul, ExLPD, and ExAnov cycles compared to SedOvul cycles and remained lower (P < 0.02) in the ExLPD and ExAnov cycles during days 6-12. The elevation in FSH during the luteal-follicular transition was lower (P < 0.007) in ExLPD (0.7+/-0.1 ng/mg Cr) cycles compared to SedOvul and ExOvul cycles (1.0+/-0.1 and 1.1+/-0.1 ng/mg Cr, respectively). Energy balance and energy availability were lower (P < 0.05) in ExAnov cycles than in other menstrual cycle categories. The blunted elevation in FSH during the luteal-follicular transition in exercising women with LPD may explain their lower follicular estradiol levels. These alterations in FSH may act in concert with disrupted LH pulsatility as a primary and proximate factor in the high frequency of luteal phase and ovulatory disturbances in regularly menstruating, exercising women.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
November/25/1999
Abstract
The aims of this study were: 1) to describe, in relation to the date of final menses, the average hormone levels of women in the years before and after this date and to determine the extent to which these average levels were dependent on age and body mass index (BMI); and 2) to determine the degree of tracking in residual hormone levels [i.e., the extent to which individuals above (below) the mean for their age or time relative to final menstrual period (FMP) and BMI remain above (below) the mean as time progresses]. Serial levels of serum FSH, circulating estradiol (E2), and the dimeric inhibins (INH) A and B were measured annually in 150 women who experienced a natural menopause during 6 years of follow-up. Means of the log-transformed hormonal levels were analyzed as a double-logistic function of time relative to FMP, as well as age and BMI and correlations between repeated hormonal levels, were measured. Mean FSH levels started to increase from about 2 years before the FMP, increased most rapidly about 10 months before the FMP, and had virtually plateaued by 2 years after the FMP. FSH levels were, on average, 3% greater for each year of age and 2% lower for each kg/m2 of BMI. After adjusting for time relative to the FMP, logFSH showed modest tracking. Age-adjusted values of logFSH were moderately correlated across time, and much of this tracking was explained by the actual timing of a woman's FMP. Mean E2 levels started to decrease about 2 years before the FMP, decreased most rapidly around the time of the FMP, and had virtually plateaued by 2 years after the FMP. E2 levels were lower, on average, by about 9% per year of age, and residual values showed weak tracking. Levels of both INHA and INHB decreased, on average, in the years before the FMP and were undetectable (INHA, < 10 pg/mL; INHB, < 25 pg/mL) in the majority of women by the time of the FMP and in almost all women by 4 years post-FMP. Significant negative correlations between log serum FSH and log E2 (r = -0.73) and log INHA (r = -0.41) and log INHB (r = -0.36) were observed. It is concluded that substantial changes in reproductive hormone levels occur within 1-2 yr on each side of the FMP, that falling concentrations of E2 and the INH contribute to the rising concentrations of FSH, and that there is no single reliable hormonal marker of menopausal status for an individual woman.
Publication
Journal: Molecular and Cellular Endocrinology
October/24/2001
Abstract
Development-related paracrine cues that sensitize follicles to follicle stimulating hormone (FSH) and luteinizing hormone (LH) are crucial to the emergence of a single dominant follicle in each ovulatory menstrual cycle. Sex steroids, insulin-like growth factors and members of the transforming growth factor-beta superfamily are key players in the follicular paracrine system. FSH acts through membrane-associated granulosa cell receptors (FSHR) to stimulate granulosa cell proliferation and differentiation. The most responsive follicle at the beginning of the cycle is the first to produce estrogen and express granulosa cell LHR. Paracrine signalling activated by FSH and LH sustains growth and oestrogen secretion until an ovulation-inducing LH surge is discharged by the pituitary gland. LH then reprograms granulosa cell function, leading to terminal differentiation (luteinization) rupture of the follicle wall, and release of the fertilizable egg. The genes regulated by the LH surge orchestrate profound changes in sex steroid production, metabolism and action which are necessary for ovulation. Preovulatory granulosa cells also increase their ability to metabolise cortisone to cortisol, which may be part of a local anti-inflammatory mechanism to promote rapid healing of the ruptured ovarian surface.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
May/10/2004
Abstract
Serum reproductive hormone concentrations were measured longitudinally in a community-based, multiethnic population of midlife women to assess whether ethnic differences exist in the patterns of change in estradiol (E2) and FSH and, if so, whether these differences are explained by host characteristics. We studied 3257 participants from seven clinical sites in the Study of Women's Health Across the Nation (SWAN) who were aged 42-52 yr at baseline and self-identified as African American (28.2%), Caucasian (47.1%), Chinese (7.7%), Hispanic (8.4%), or Japanese (8.6%). E2 and FSH were assayed in serum collected primarily in the early follicular phase of a spontaneous menstrual cycle in three consecutive annual visits. The primary explanatory variables included in repeated-measures regression analyses were race/ethnicity, menopausal status, age, body mass index (BMI), day of the cycle, smoking, parity, socioeconomic status, study site, and the self-report of diabetes at baseline. At the baseline visit, 46.2% of the women were classified as being early perimenopausal, with the remaining being premenopausal. By the second follow-up visit, 5.5% of the women in that cohort were postmenopausal, 66.8% were early perimenopausal, 8.3% were late perimenopausal, and 19.4% remained premenopausal. Serum E2 concentrations decreased significantly with age, with a steeper decline at higher ages. FSH concentrations increased significantly with age, with a steeper increase at higher ages. Similar patterns in the decline of E2 and the increase in FSH with age were found across ethnic groups, but the levels of these hormones differed by race/ethnicity. Specifically, over time, Chinese and Japanese women had lower E2 concentrations but similar FSH levels, compared with Caucasian women, and African American women had higher FSH concentrations but comparable E2 levels with those of Caucasian women. These ethnic differences in E2 and FSH were independent of menopausal status. The effect of BMI on serum E2 and FSH levels varied by menopausal status. Increasing BMI was associated with decreasing concentrations of E2 among premenopausal and early perimenopausal women but was associated with increasing concentrations of E2 among late perimenopausal and postmenopausal women. Increasing BMI was associated with decreasing concentrations of FSH, with the effect of BMI becoming larger as women transitioned through menopause. We conclude that serum E2 levels decrease and FSH concentrations increase with increasing age in midlife women, that ethnic differences in E2 over time differ from ethnic differences in FSH and suggest ethnic differences in the pituitary-ovarian relationship, and that the effect of BMI on E2 and FSH concentrations varies by menopausal status.
Publication
Journal: JAMA - Journal of the American Medical Association
August/19/1984
Abstract
To investigate whether endurance running in men produced basal hormonal changes similar to those reported in women, we obtained blood samples from 31 men running at least 64 km each week and 18 sedentary controls for measurement of levels of total testosterone, non-sex hormone-binding globulin-bound and free testosterone, luteinizing hormone, follicle-stimulating hormone, prolactin, and cortisol. The mean levels of total and nonspecifically bound testosterone as well as prolactin were significantly lower than in controls, although levels remained within the physiological range. Other hormone levels were similar in both groups. The lowered testosterone and prolactin levels parallel the changes reported in women runners.
Publication
Journal: Cytokine and Growth Factor Reviews
July/26/2006
Abstract
Activins are transforming growth factor beta superfamily members, which were originally identified as inducers of follicle-stimulating hormone release from the pituitary. In recent years, however, additional functions of activins have been discovered, including a role in the morphogenesis of various tissues and organs. In addition, they have been identified as novel players in inflammation and repair, and are most likely involved in the pathogenesis of inflammatory and fibrotic human diseases. In this review we highlight recent data regarding the expression and function of activins in tissue repair, fibrosis, and inflammation.
Publication
Journal: Menopause
March/22/2005
Abstract
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.
METHODS
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.
Publication
Journal: Human Reproduction
April/9/1997
Abstract
A simplified culture system was developed for the in-vitro maturation of early preantral mouse ovarian follicles. The follicles were cultured singly in 20 microliters droplets under oil in medium supplemented with recombinant follicle stimulating hormone (r-FSH) at 37 degrees C and 5% CO2 in air. The follicles grew and became attached to the bottom of the dish, progressively lost their spherical structure by outgrowth of the granulosa cells through the basal membrane and developed follicles with antral-like cavities. The normal three-dimensional follicular structure was lost but all components, i.e. theca, granulosa and oocyte, remained functional, as was proven by the oestradiol, inhibin and progesterone secretion patterns. Follicle survival exceeded 80% and histological analysis proved the absence of atresia and cell death in granulosa cells up to day 16. Oocytes of 55 (+/-4) microns diameter on the day of isolation reached 74 (+/-3) microns by day 16 of culture. The optimal moment for inducing the final meiotic maturation with human chorionic gonadotrophin was investigated: the highest absolute numbers of metaphase II oocytes were obtained on days 12 and 14 (39 and 41%). The fertilizing potential of the in-vitro matured oocytes was comparable to in-vivo matured controls. A 50% hatched-blastocyst development rate was observed.
Publication
Journal: Endocrine Practice
August/4/2004
Abstract
In these clinical practice guidelines, specific recommendations are made for determining the most effective methods of diagnosing and treating hypogonadism in adult male patients. The target populations for these guidelines include the following: (1) men with primary testicular failure requiring testosterone replacement (hypergonadotropic hypogonadism); (2) male patients with gonadotropin deficiency or dysfunction who may have received testosterone replacement therapy or treatment for infertility (hypogonadotropic hypogonadism); and (3) aging men with symptoms relating to testosterone deficiency who could benefit from testosterone replacement therapy. Initial hormonal evaluation generally consists of a testosterone determination, in conjunction with a free testosterone or sex hormone-binding globulin level, inpatients with clear symptoms and signs but normal-range total testosterone, follicle-stimulating hormone, luteinizing hormone, and prolactin levels. Other possible tests include semen analysis, pituitary imaging studies, genetic studies, bone densitometry, testicular ultrasonography,testicular biopsy, and specialized hormonal dynamic testing. Therapeutic options generally consist of testosterone replacement by injections, patches, or topically applied gel in hypergonadotropic patients and in hypogonadotropic patients not interested in fertility. In hypogonadotropic patients interested in fertility, gonadal stimulation option scan be considered, including human chorionic gonadotropin stimulation therapy with or without human menopausal gonadotropin (or follicle-stimulating hormone) or gonadotropin-releasing hormone pump therapy. These therapies may be combined with assisted reproductive technologies such as in vitro fertilization with intracytoplasmic sperm injection, which may allow pregnancy to occur with very low numbers of sperm.
Publication
Journal: The Lancet
February/17/1978
Abstract
A number of cases of infertility were discovered among men working in a California pesticide factory. The suspected cause was exposure to the chemical 1,2-dibromo-3-chloropropane (D.B.C.P.). The major effects, seen in 14 of 25 non-vasectomised men, were azoospermia or oligospermia and raised serum-levels of follicle-stimulating hormone and luteinising hormone. No other major abnormalities were detected, and testosterone levels were normal. Although a quantitative estimation of exposure could not be obtained, the observed effects appeared to be related to duration of exposure to D.B.C.P.
Publication
Journal: Journal of Clinical Investigation
July/5/1976
Abstract
To evaluate gonadotropin release in polycystic ovary syndrome (PCO), one or more of the following hypothalamic-pituitary function tests were performed on 24 patients with the syndrome. These tests included (a) the pulsatile pattern and day-to-day fluctuation of gonadotropin release; (b) effects of exogenous estrogen and antiestrogen (clomiphene) administration on gonadotropin release; and (c) pituitary responsiveness to maximal (150 mug) and submaximal (10 mug) luteinizing hormone-releasing factor (LRF) injections. In 10 of the 14 patients sampled frequently (15 min) for 6 h, luteinizing hormone (LH) levels were elevated above the concentration seen in normal cycling women (except the LH surge). These high LH concentrations appeared to be maintained by and temporally related to the presence of exaggerated pulsatile LH release, either in the form of enhanced amplitude or increased frequency. In all subjects, levels of follicle-stimulating hormone (FSH) were low or low normal, and a pulsatile pattern was not discernible. In four patients, daily sampling revealed marked day-to-day fluctuation of LH but not FSH. That the elevated LH levels were not related to a defect in the negative-feedback effect of estrogen was suggested by the appropriate fall of LH in four patients given an acute intravenous infusion of 17beta-estradiol. This infusion had no effect on FSH levels. In addition, clomiphene elicited rises of both LH and FSH that were comparable to the ones observed in normal women given the same treatment. The clomiphene study also suggested that the positive-feed-back mechanism of estrogen on LH release was intact when the preovulatory rises of 17beta-estradiol induced appropriate LH surges. The elevated LH levels appeared to be related to a heightened pituitary responsiveness to the LRF. This was found in the 11 and 2 patients given maximal (150 mug) and submaximal (10 mug) doses of LRF, respectively. The augmented pituitary sensitivity for LH release correlated with the basal levels of both estrone (P less than 0.025) and 17beta-estradiol (P less than 0.02). The net increase in FSH was significantly greater (P less than 0.001) in the PCO patients than the normal women with maximal doses of LRF. With the smaller dose study none of the injections had a discernible effect on FSH concentrations in either subject. The disparity between LH and FSH secretion could be explained by the preferential inhibitory action of estrogen on FSH release, coupled with a relative insensitivity of FSH release. These data indicate that in these PCO patients the abnormalities of the hypothalamic-pituitary regulation of gonadotropin secretion was not an inherent defect but represented a functional derangement consequent to inappropriate estrogen feedback, which led to a vicious cycle of chronic anovulation and inappropriate gonadotropin secretion.
Publication
Journal: Journal of Clinical Endocrinology and Metabolism
July/5/1976
Abstract
Studies of menstrual cycle length in large populations demonstrated that there is a striking increase in the variability of intermenstrual intervals just before menopause. The changes in serum concentrations of luteinizing hormone (LH), follicle-stimulating hormone (FSH), estradiol (E2), and progesterone (P) during menstrual cycles in a group of perimenopausal women were compared with the findings in young normal women. In 8 women, 46-56 years old with regular cycles, cycle length was shorter and the mean E2 concentration was lower than in younger women. There was a striking increase in FSH concentration throughout the cycle while LH remained in the normal range. In 2 women, 14 cycles of variable length were studied during 2 years of the menopausal transition. In some instances, hormonal changes associated with follicular maturation and corpus luteum function occurred in the presence of high, menopausal levels of LH and FSH with a diminished secretion of E2 and P. In others vaginal bleeding occurred during a fall in serum E2 with no associated rise in P. Cycles of variable length during the menopausal transition may be due either to irregular maturation of residual follicles with diminished responsiveness to gonadotropin stimulation, or to anovulatory vaginal bleeding that may follow estrogen withdrawal without evidence of corpus luteum function. The observation of elevated FSH concentrations and normal LH levels in perimenopausal women emphasizes the complexity of the hypothalamic-pituitary-ovarian regulatory system and suggests that LH and FSH are modulated independently at the level of the pituitary.
Publication
Journal: Biology of Reproduction
January/4/2010
Abstract
In vitro ovarian <em>follicle</em> cultures may provide fertility-preserving options to women facing premature infertility due to cancer therapies. An encapsulated three-dimensional (3-D) culture system utilizing biomaterials to maintain cell-cell communication and support <em>follicle</em> development to produce a mature oocyte has been developed for the mouse. We tested whether this encapsulated 3-D system would also support development of nonhuman primate preantral <em>follicles</em>, for which in vitro growth has not been reported. Three questions were investigated: Does the cycle stage at which the <em>follicles</em> are isolated affect <em>follicle</em> development? Does the rigidity of the hydrogel influence <em>follicle</em> survival and growth? Do <em>follicles</em> require luteinizing <em>hormone</em> (LH), in addition to <em>follicle</em>-<em>stimulating</em> <em>hormone</em> (FSH), for steroidogenesis? Secondary <em>follicles</em> were isolated from adult rhesus monkeys, encapsulated within alginate hydrogels, and cultured individually for </=30 days. <em>Follicles</em> isolated from the follicular phase of the menstrual cycle had a higher survival rate (P < 0.05) than those isolated from the luteal phase; however, this difference may also be attributed to differing sizes of <em>follicles</em> isolated during the different stages. <em>Follicles</em> survived and grew in two hydrogel conditions (0.5% and 0.25% alginate). <em>Follicle</em> diameters increased to a greater extent (P < 0.05) in the presence of FSH alone than in FSH plus LH. Regardless of gonadotropin treatment, <em>follicles</em> produced estradiol, androstenedione, and progesterone by 14-30 days in vitro. Thus, an alginate hydrogel maintains the 3-D structure of individual secondary macaque <em>follicles</em>, permits <em>follicle</em> growth, and supports steroidogenesis for </=30 days in vitro. This study documents the first use of the alginate system to maintain primate tissue architecture, and findings suggest that encapsulated 3-D culture will be successful in supporting the in vitro development of human <em>follicles</em>.
Publication
Journal: Menopause
July/31/2012
Abstract
OBJECTIVE
The aim of this article is to summarize the recommended updates to the 2001 Stages of Reproductive Aging Workshop (STRAW) criteria. The 2011 STRAW + 10 reviewed advances in understanding of the critical changes in hypothalamic-pituitary-ovarian function that occur before and after the final menstrual period.
METHODS
Scientists from five countries and multiple disciplines evaluated data from cohort studies of midlife women and in the context of chronic illness and endocrine disorders on change in menstrual, endocrine, and ovarian markers of reproductive aging including antimüllerian hormone, inhibin-B, follicle-stimulating hormone, and antral follicle count. Modifications were adopted by consensus.
RESULTS
STRAW + 10 simplified bleeding criteria for the early and late menopausal transition, recommended modifications to criteria for the late reproductive stage (Stage -3) and the early postmenopause stage (Stage +1), provided information on the duration of the late transition (Stage -1) and early postmenopause (Stage +1), and recommended application regardless of women's age, ethnicity, body size, or lifestyle characteristics.
CONCLUSIONS
STRAW + 10 provides a more comprehensive basis for assessing reproductive aging in research and clinical contexts. Application of the STRAW + 10 staging system should improve comparability of studies of midlife women and facilitate clinical decision making. Nonetheless, important knowledge gaps persist, and seven research priorities are identified.
Publication
Journal: Journal of Biological Chemistry
March/2/2004
Abstract
Regulation of follicle-stimulating hormone (FSH) synthesis is a central point of convergence for signals controlling reproduction. The FSHbeta subunit is primarily regulated by gonadotropin-releasing hormone (GnRH), gonadal steroids, and activin. Here, we identify elements in the mouse FSHbeta promoter responsible for GnRH-mediated induction utilizing the LbetaT2 cell line that endogenously expresses FSH. The proximal 398 bp of the mouse FSHbeta promoter is sufficient for response to GnRH. This response localizes primarily to an AP-1 half-site (-72/-69) juxtaposed to a CCAAT box, which binds nuclear factor-Y. Both elements are required for AP-1 binding, creating a novel AP-1 site. Multimers of this site confer GnRH induction, and mutation or internal deletion of this site reduces GnRH induction by 35%. The same reduction was achieved using a dominant negative Fos protein. This is the only functional AP-1 site identified in the proximal 398 bp, since its mutation eliminates FSHbeta induction by c-Fos and c-Jun. GnRH regulation of the FSHbeta gene occurs through induction of multiple Fos and Jun isoforms, forming at least four different AP-1 molecules, all of which bind to this site. Mitogen-activated protein kinase activity is required for induction of FSHbeta and JunB protein. Finally, AP-1 interacts with nuclear factor-Y, which occupies its overlapping site in vivo.
Publication
Journal: Journal of Pain
December/18/2003
Abstract
Naturally occurring opiates (endorphins) diminish testosterone levels by inhibiting both hypothalamic gonadotrophin releasing hormone production and testicular testosterone synthesis. Heroin addicts treated with a single daily dose of methadone and nonaddicts receiving continuous intrathecal opioids quickly develop low luteinizing hormone and total testosterone levels. A similar pattern was sought in men consuming commonly prescribed oral opioids. Free testosterone (FT), total testosterone (TT), estradiol (E(2)), dihydrotestosterone (DHT), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) were measured in 54 community-dwelling outpatient men consuming oral sustained-action dosage forms of opioids several times daily for control of nonmalignant pain. Hormone levels were related to the opioid consumed, dosage and dosage form, nonopioid medication use, and several personal characteristics and were compared with the hormone analyses of 27 similar men consuming no opioids. Hormone levels averaged much lower in opioid users than in control subjects in a dose-related pattern (P < .0001 for all comparisons). FT, TT, and E(2) levels were subnormal in 56%, 74%, and 74%, respectively, of opioid consumers. Forty-eight men (89%) exhibited subnormal levels of either FT or E(2). Either TT or E(2) level was subnormal in all 28 men consuming the equivalent of 100 mg of methadone daily and in 19 of 26 (73%) consuming smaller opioid doses. Eighty-seven percent (39 of 45) of opioid-ingesting men who reported normal erectile function before opioid use reported severe erectile dysfunction or diminished libido after beginning their opioid therapy. Commonly prescribed opioids in sustained-action dosage forms usually produce subnormal sex hormone levels, which may contribute to a diminished quality of life for many patients with painful chronic illness.
Publication
Journal: Journal of Molecular Endocrinology
April/27/2005
Abstract
Reproductive function in mammals is regulated by the pituitary gonadotropins luteinizing hormone (LH) and follicle-stimulating hormone (FSH). LH and FSH are secreted by the gonadotrope cell and act on the gonad in a sequential and synergistic manner to initiate sexual maturation and maintain cyclic reproductive function. The synthesis and secretion of LH and FSH are regulated mainly by the pulsatile release of the hypothalamic decapeptide hormone gonadotropin-releasing hormone (GnRH). The control of differential LH and FSH synthesis and secretion is complex and involves the interplay between the gonads, hypothalamus and pituitary. In this review, the transcriptional regulation of the gonadotropin subunit genes is discussed in a physiologic setting, and we aimed to examine the mechanisms that drive those changes.
Publication
Journal: Recent progress in hormone research
June/3/2002
Abstract
A detailed understanding of the hormonal regulation of spermatogenesis is required for the informed assessment and management of male fertility and, conversely, for the development of safe and reversible male hormonal contraception. An approach to the study of these issues is outlined based on the use of well-defined in vivo models of gonadotropin/androgen deprivation and replacement, the quantitative assessment of germ cell number using stereological techniques, and the directed study of specific steps in spermatogenesis shown to be hormone dependent. Drawing together data from rat, monkey, and human models, we identify differences between species and formulate an overview of the hormonal regulation of spermatogenesis. There is good evidence for both separate and synergistic roles for both testosterone and follicle-stimulating hormone (FSH) in achieving quantitatively normal spermatogenesis. Based on relatively selective withdrawal and replacement studies, FSH has key roles in the progression of type A to B spermatogonia and, in synergy with testosterone, in regulating germ cell viability. Testosterone is an absolute requirement for spermatogenesis. In rats, it has been shown to promote the adhesion of round spermatids to Sertoli cells, without which they are sloughed from the epithelium and spermatid elongation fails. The release of mature elongated spermatids from the testis (spermiation) is also under FSH/testosterone control in rats. Data from monkeys and men treated with steroidal contraceptives indicate that impairment of spermiation is a key to achieving azoospermia. The contribution of 5alpha-reduced androgens in the testis to the regulation of spermatogenesis is also relevant, as 5alpha-reduced androgens are maintained during gonadotropin suppression and may act to maintain low levels of germ cell development. These concepts are also discussed in the context of male hormonal contraceptive development.
Publication
Journal: Mechanisms of Development
October/7/2002
Abstract
Stem cell regulatory mechanisms are difficult to study because self-renewal and production of differentiated progeny, which are both strictly controlled, occur simultaneously in these cells. To focus on the self-renewal mechanism alone, we investigated the behavior of germinal stem cells (GSCs) in progeny-deficient testes with defective GSC differentiation. In these testes, we found that the proliferation of undifferentiated spermatogonia, some of which are GSCs, was accelerated by high concentrations of glial cell line-derived neurotrophic factor (GDNF). Furthermore, we found that follicle-stimulating hormone (FSH) stimulation via homeostatic control was one of the major regulators of GDNF concentration. These results suggest that in mammalian testes, GSC proliferation and population size are regulated homeostatically by the GDNF/FSH pathway.
Publication
Journal: The Lancet
January/28/1986
Abstract
By means of pelvic ultrasonography, a multifollicular ovarian appearance was observed in women with weight-loss-related amenorrhoea. Multifollicular ovaries (MFO) are normal in size or slightly enlarged and filled by six or more cysts 4-10 mm in diameter; in contrast to women with polycystic ovaries (PCO), stroma is not increased. Unlike PCO patients, women with MFO were not hirsute and serum concentrations of luteinising hormone and follicle stimulating hormone were normal and decreased, respectively. The uterus was small indicating oestrogen deficiency. In MFO, treatment with gonadotropin releasing hormone (LHRH) induced ovulation in 83% of cycles and there were seven pregnancies in 8 women; in PCO, only 40% of cycles were ovulatory and there were eleven pregnancies (8 women) but six of these aborted. In MFO ovarian morphology reverted to normal in ovulatory cycles, whereas in PCO the polycystic pattern persisted despite the presence of a dominant follicle. MFO may represent a normal ovarian response to weight-related hypothalamic disturbance of gonadotropin control.
Publication
Journal: BioEssays
September/29/2004
Abstract
In the seminiferous tubule of the mammalian testis, one type A1 spermatogonium (diploid, 2n) divides and differentiates into 256 spermatozoa (haploid, n) during spermatogenesis. To complete spermatogenesis and produce approximately 150 x 10(6) spermatozoa each day in a healthy man, germ cells must migrate progressively across the seminiferous epithelium yet remain attach to the nourishing Sertoli cells. This active cell migration process involves precisely controlled restructuring events at the tight (TJ) and anchoring junctions at the cell-cell interface. While the hormonal events that regulate spermatogenesis by follicle-stimulating hormone and testosterone from the pituitary gland and Leydig cells, respectively, are known, less is known about the mechanism(s) that regulates junction restructuring during germ cell movement in the seminiferous epithelium. The relative position of tight (TJs) and anchoring junctions in the testis is of interest. Sertoli cell TJs that constitute the blood-testis barrier (BTB) are present side by side with anchoring junctions and are adjacent to the basement membrane. This intimate physical association with the TJs, the anchoring junctions and the basement membrane (a modified form of extracellular matrix, ECM) suggests a role for the ECM in the junction dynamics of the testis. Indeed, evidence is accumulating that ECM proteins are crucial to Sertoli cell TJ dynamics. In this review, we discuss the pivotal role of tumor necrosis factor alpha (TNFalpha) on BTB dynamics via its effects on the homeostasis of ECM proteins. In addition, discussion will also be focused on the novel findings regarding the role of non-basement-membrane-associated ECM proteins and components of focal adhesion (a cell-matrix anchoring junction type) in the regulation of junction dynamics in the testis.
Publication
Journal: Cancer Causes and Control
May/9/2001
Abstract
OBJECTIVE
To investigate the relationships between plasma concentrations of sex hormones and risk factors for breast cancer.
METHODS
We investigated the relationship of plasma concentrations of estradiol, progesterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH) and sex hormone-binding globulin (SHBG) with breast cancer risk factors in 636 premenopausal and 456 postmenopausal women. Risk factor data were obtained from questionnaires and hormone concentrations measured by immunoassays; variations in geometric means were compared using analysis of covariance.
RESULTS
SHBG decreased with increasing body mass index and increasing waist-hip ratio both in pre- and postmenopausal women. In postmenopausal women only, estradiol increased with increasing body mass index. In premenopausal women, estradiol decreased with increasing physical activity, estradiol was higher in current than in ex- and non-smokers, and FSH decreased with increasing alcohol intake. No associations were observed between sex hormones and age at menarche, parity, age at menopause, and previous use of oral contraceptives in either pre- or postmenopausal women.
CONCLUSIONS
Certain factors such as obesity and perhaps waist-hip ratio, physical activity and alcohol consumption, but probably not age at menarche and parity, may mediate their effects on breast cancer risk by changing circulating concentrations of sex hormones.
Publication
Journal: EMBO Journal
April/18/2002
Abstract
The glycoprotein hormone receptors (thyrotrophin receptor, TSHr; luteinizing hormone/chorionic gonadotrophin receptor, LH/CGr; follicle-stimulating hormone receptor, FSHr) constitute a subfamily of rhodopsin-like G protein-coupled receptors (GPCRs) with a long N-terminal extracellular extension responsible for high-affinity hormone binding. These ectodomains contain two cysteine clusters flanking nine leucine-rich repeats (LRR), a motif found in several protein families involved in protein-protein interactions. Similar to the situation described recently in CCR5, we demonstrate here that the TSHr, as it is present at the cell surface, is sulfated on tyrosines in a motif located downstream of the C-terminal cysteine cluster. Sulfation of one of the two tyrosines in the motif is mandatory for high-affinity binding of TSH and activation of the receptor. Site-directed mutagenesis experiments indicate that the motif, which is conserved in all members of the glycoprotein hormone receptor family, seems to play a similar role in the LH/CG and FSH receptors.
load more...