Gonadotropic control of ovarian follicular growth and development

Origin and Identity of Adrenocortical Tumors in Inhibin Knockout Mice: Implications for Cellular Plasticity in the Adrenal Cortex

Inhibin knockout (Inha−/−) mice develop gonadal sex-cord tumors and—when gonadectomized—adrenocortical tumors. Previous reports demonstrated that adrenocortical tumors from Inha−/− mice produce estrogen and depend on gonadotropin signaling for initiation. Here we show that, in addition to producing estrogen, the adrenocortical tumors display a global change in cellular identity, composed of two unique cell types expressing differing arrays of genes normally restricted to theca and granulosa cells of the ovary. Many of these genes are also induced in wild-type adrenals after gonadectomy or upon chronic gonadotropin stimulation, suggesting that the adrenal cortex normally contains a population of pluripotent cells that can be driven toward an adrenal or gonadal identity given the appropriate pituitary stimuli. A central feature of this altered cellular identity is the switch from predominant expression of Gata6 (endogenous to the adrenal cortex) to Gata4, which defines cellular identity in the ovary. We show that stable transfection of Gata4 in cultured adrenocortical cells is sufficient to activate ovarian-specific genes of both theca and granulose lineages. Spatial analysis of Gata4 expression reveals a distinct pattern of localization to the supcapsular region of the adrenal, which contains undifferentiated progenitor cells that continuously populate the adrenocortical zones. Although both wild-type and Inha−/− mice display this pattern, only Inha−/− mice produce tumors composed of these Gata4-positive cells. These data suggest that Inha−/− adrenocortical tumors cells are derived from pluripotent adrenocortical progenitor cells that adopt a gonadal fate due to the convergent loss of inhibin and chronic exposure to elevated gonadotropins.

Induction of apoptosis increases SUMO-1 protein expression and conjugation in mouse periovulatory granulosa cells in vitro

The small ubiquitin-related modifier-1 (SUMO-1) with broad cellular expression has been implicated in a range of cellular processes, such as cell proliferation, differentiation, and apoptosis. As shown recently, SUMO-1 is expressed and regulated by gonadotropins, in particular an ovulatory hCG stimulus in mouse granulosa cells in vivo. To test the hypothesis that modulation of granulosa cell apoptosis changes SUMO-1 expression during granulosa cell differentiation in the mouse ovary, we demonstrate that progesterone receptor (PR) proteins are absent in pre-ovulatory granulosa cell nuclei, whereas they are expressed in periovulatory granulosa cell nuclei in parallel with decreases in SUMO-1 expression, caspase-3 activation, and DNA fragmentation in vivo. Second, treatment with either PR antagonists or a cell permeable ceramide analog consistently increases SUMO-1 expression in parallel with an increase in apoptosis as well as a decrease in cell proliferation in periovulatory granulosa cells in vitro. However, we do not observe an increase in SUMO-1 expression in pre-ovulatory granulosa cells that have undergone the same treatment. Third, we have also demonstrated, in pre-ovulatory granulosa cells in vitro, neither induction of spontaneous apoptosis nor the protective effect of EGF against spontaneous apoptosis changes SUMO-1 protein expression. Fourth, we show that induction of apoptosis enhances SUMO-1 conjugation in periovulatory granulosa cells in vitro, pointing to the pivotal link between the SUMO-1 conjugation and cell death. Taken together, our observations suggest that SUMO-1 via sumoylation has an important role in the regulation of granulosa cell apoptosis during granulosa cell differentiation in the mouse ovary.

Circadian Clock Gene Expression in the Ovary: Effects of Luteinizing Hormone1

A molecular device that measures time on a daily, or circadian, scale is a nearly ubiquitous feature of eukaryotic organisms. A core group of clock genes, whose coordinated function is required for this timekeeping, is expressed both in the central clock and within numerous peripheral organs. We examined expression of clock genes in the rat ovary. Transcripts for core oscillator elements (Arntl, Clock, Per1, Per2, and Cry1) were present in the ovary as indicated by quantitative real-time RT-PCR. Rhythmic expression patterns of Arntl and Per2 transcripts and protein products were out of phase with respect to the central oscillator and in complete antiphase to each other. Expression of Arntl was significantly elevated after the LH surge on the day of proestrus. Finally, hCG treatment induced cyclic expression of both Arntl and Per2 gene products in hypophysectomized, immature rats primed with eCG. Collectively, these data suggest that the core underpinnings of the transcriptional/translational feedback loop that drives circadian rhythmicity is present in the rat ovary. Furthermore, the study identifies LH as a potential regulator of circadian clock gene rhythms in the ovary.

Biological properties of a novel follicle-stimulating hormone/human chorionic gonadotropin chimeric gonadotropin

A chimeric recombinant human gonadotropin, termed C3, demonstrates both follitropic and lutropic bioactivities. The alpha-subunit construct for C3 is comprised of the recombinant wild-type human glycoprotein hormone alpha-subunit. The beta-subunit DNA construct for C3 encodes residues 1-145 from human chorionic gonadotropin (hCG)-beta with the exceptions that FSH beta amino acid 88 (D) is substituted for hCG beta amino acid 94 (R) and FSH beta amino acids 95-108 (TVRGLGPSYCSFGE) are substituted for hCG beta amino acids 101-114 (GGPKDHPLTCDDPR). C3 is a potent FSH and LH agonist able to bind and to signal through FSH and LH receptors in vitro. In in vivo bioassays optimized to quantify each type of activity, C3 was found to have lutropin and follitropin potencies at levels similar to those of recombinant human LH and recombinant human FSH, respectively. In immature rats, C3 was sufficient to support the maturation of normal ovarian follicles. Moreover, a significant portion of follicles matured by C3 ruptured in response to an ovulatory hCG stimulus and gave rise to morphologically normal oocytes. Furthermore, a low dose of C3 promoted weight gain in the rodent uterus, suggesting it also supported preparation for implantation without histological evidence of excessive luteinization of the ovary. In summary, the biological properties of C3 indicate that its chimeric nature has resulted in a fully functional, dual-acting human gonadotropin.

Steroidogenic alterations and adrenal androgen excess in PCOS

BACKGROUND

This cross-sectional study was undertaken to improve our understanding of the steroidogenic alterations leading to adrenal hyperandrogenism in polycystic ovarian syndrome (PCOS).

METHODS

Two-hundred and thirty-four women with clinical and biochemical features suggestive of PCOS underwent metabolic and hormonal evaluation. We used the androstenedione/DHEAS ratio as a surrogate for the level of ovarian 3betaHSD activity. We then selected the 90th percentile for the ratio in those with elevated DHEAS (>9 micromol/l) as the cut-off level beyond which excess DHEAS production will be minimized by excess ovarian 3betaHSD activity. This cut-off level was at a ratio of 1.5 and all PCOS women were then divided into two groups, the higher (>1.5) being the group with excess ovarian 3betaHSD activity. We hypothesized that women with a high ratio would be unlikely to have DHEAS excess due to the rapid conversion of DHEA to androstenedione. Those with a low ratio (concordant ovarian and adrenal steroidogenesis) could then either have high DHEAS or normal DHEAS, depending on whether CYP17 activity was higher or lower respectively.

RESULTS

Insulin resistance was found to be associated with decreased CYP17 activity while irregular cycles and neuroendocrine dysfunction were determined to be associated with higher ovarian 3betaHSD activity.

CONCLUSION

Adrenal androgen excess in PCOS seems to be related to insulin sensitivity as well as decreased activity of 3betaHSD, the latter being preferentially present in those women with regular cycles or without neuroendocrine dysfunction.

LH in the follicular phase: neither too high nor too low

The role of LH in the natural menstrual cycle is not disputed. However, there are a variety of opinions regarding the potential role of exogenous LH in ovulation induction and whether it is actually needed. Recent years have seen renewed interest in this issue for several reasons. First, ovulation-inducing drugs are increasingly being administered to normally ovulating women. Second, recombinant human FSH products completely devoid of LH activity are now available. Third, gonadotrophin-releasing hormone (GnRH) analogues (agonists and antagonists) prevent the untimely LH surge but also suppress endogenous LH activity during the follicular phase. This review analyses whether or not all patients need LH for follicular growth stimulation and new opportunities for improved treatment as a result of the availability of recombinant human LH both in patients with ovulatory disorders (World Health Organization (WHO) groups I and II anovulatory patients) and those undergoing multiple follicular development for assisted reproduction.

Ovarian steroids: the good, the bad, and the signals that raise them

Ovarian steroid production and subsequent local steroid-mediated signaling are critical for normal ovarian processes, including follicle growth, oocyte maturation, and ovulation. In contrast, elevated steroidogenesis and/or increased steroid signaling in the ovary can lead to profound ovarian pathology, such as polycystic ovarian syndrome, the leading cause of infertility in reproductive age women. Through the use of several in vitro and animal models, great strides have been made toward characterizing the mechanisms regulating local steroid production and action in the ovary. Examples of this progress include insights into luteinizing hormone (LH)- and growth factor-mediated signaling, steroidogenic acute regulatory protein (StAR) activation, and both genomic and nongenomic steroid-mediated signaling in somatic and germ cells, respectively. The following review will address these advances, focusing on how this rapidly expanding knowledge base can be used to better understand female reproduction, and to further improve treatments for common diseases of infertility.

Gonadotropin-releasing hormone antagonists increase follicular fluid insulin-like growth factor-I and vascular endothelial growth factor during ovarian stimulation cycles

The aim of the present study was to investigate the effect of gonadotropin-releasing hormone (GnRH) antagonists (GnRH-ant) on follicular fluid (FF) insulin-like growth factor-I (IGF-I) and FF vascular endothelial growth factor (VEGF) levels. Sixty women undergoing assisted reproduction were randomized and assigned to two different GnRH analog regimens: GnRH agonist (GnRH-a) and GnRH-ant. FF VEGF and FF IGF-I concentrations were significantly increased in the patients treated with GnRH-ant (p < 0.001). In the same patients we observed a statistically significant reduction in serum luteinizing hormone (LH) and estradiol (E2) levels (p < 0.001 and p < 0.05, respectively), FF E2 and FF androstenedione levels (p < 0.05 and p < 0.001, respectively), as well as a reduction in the number of pregnancies although this was not statistically significant. In the GnRH-ant group, FF VEGF levels were positively correlated with FF IGF-I levels, and both were negatively correlated with serum LH levels. The increase in FF IGF-I and FF VEGF levels in women treated with GnRH-ant could be explained by a deleterious follicular environment in response to profound suppression of LH and E2 levels.

Oocyte-granulosa cell interactions during mouse follicular development: regulation of kit ligand expression and its role in oocyte growth

Ovarian folliculogenesis is regulated by both endocrine and intraovarian mechanisms that coordinate the processes of oocyte growth and somatic cell proliferation and differentiation. Within the follicle, paracrine interactions between the oocyte and surrounding granulosa cells are critical for normal cell development and function. This review focuses on the role of paracrine interactions during early oocyte and follicular development that ensure proper coordination of oocyte and somatic cell function. Particular emphasis is given to granulosa cell-derived Kit Ligand (KitL), whose functional importance for oocyte growth has been demonstrated by a wide range of in vivo and in vitro studies. Reported interactions between KitL and oocyte-derived growth differentiation factor-9 (GDF9) and bone morphogenetic protein-15 (BMP15) suggest the molecular basis of oocyte-granulosa cell interactions, but also hint at the complexity of these communications. These paracrine interactions and the structure of the oocyte-granulosa cell interface are follicle stage-specific and regulated by FSH. Elucidation of the molecular mechanisms that promote the development of healthy oocytes with good developmental competence has potential applications for improving fertility and for in vitro growth systems for oocytes from domestic animals and humans.

Effects of recombinant human luteinizing hormone supplementation on ovarian stimulation and the implantation rate in down-regulated women of advanced reproductive age

OBJECTIVE

To evaluate the effects of recombinant human luteinizing hormone (rhLH) supplementation on ovarian stimulation and implantation rate in down-regulated women of advanced reproductive age.

DESIGN

Prospective randomized study.

SETTING

University teaching hospital.

PATIENT(S)

A total of 120 consecutive normogonadotropic infertile women > or = 35 years old undergoing their first cycle of IVF or intracytoplasmic sperm injection (ICSI) treatment.

INTERVENTION(S)

Ovarian stimulation in a long agonist protocol with a combination of recombinant human follicle-stimulating hormone (rhFSH) and rhLH (group 1, n = 60) starting on day 6 of FSH stimulation until hCG at a daily fixed dose of 150 IU of rhLH, or with rhFSH alone (group 2, n = 60).

MAIN OUTCOME MEASURE(S)

Ovarian stimulation characteristics, ovum retrieval, and IVF/ICSI outcome.

RESULT(S)

The mean number of intermediate (10-14 mm) and large (> 14- < 18 mm) but not leading (> or = 18 mm) follicles was significantly lower in group 1 on the day of hCG injection. The oocyte yield and maturity as well as the number of oocytes fertilized were significantly higher in group 2 than in group 1. However, the number of patients having embryo transfer (n = 55 in both treatment groups), the number and quality of embryos replaced, the implantation rate (20.6% vs. 21.7%) and clinical pregnancy rates per embryo transfer (44% vs. 45%) were similar in groups 1 and 2.

CONCLUSION(S)

The rhLH supplementation does not increase ovarian response and implantation rates in patients of older reproductive age stimulated with rhFSH under pituitary suppression for assisted reproductive technologies (ARTs).

Ovarian aging and menopause: current theories, hypotheses, and research models

Aging of the reproductive system has been studied in numerous vertebrate species. Although there are wide variations in reproductive strategies and hormone cycle components, many of the fundamental changes that occur during aging are similar. Evolutionary hypotheses attempt to explain why menopause occurs, whereas cellular hypotheses attempt to explain how it occurs. It is commonly believed that a disruption in the hypothalamic-pituitary-gonadal axis is responsible for the onset of menopause. Data exist to demonstrate that the first signs of menopause occur at the level of the brain or the ovary. Thus, finding an appropriate and representative animal model is especially important for the advancement of menopause research. In primates, there is a gradual decline in the function of the hypothalamic-pituitary-gonadal (HPG) axis ultimately resulting in irregularities in menstrual cycles and increasingly sporadic incidence of ovulation. Rodents also exhibit a progressive deterioration in HPG axis function; however, they also experience a period of constant estrus accompanied by intermittent ovulations, reduced progesterone levels, and elevated circulating estradiol levels. It is remarkable to observe that females of other classes also demonstrate deterioration in HPG axis function and ovarian failure. Comparisons of aging in various taxa provide insight into fundamental biological mechanisms of aging that could underlie reproductive decline.

Evaluating the role of exogenous luteinizing hormone in poor responders undergoing in vitro fertilization with gonadotropin-releasing hormone antagonists

OBJECTIVE

To evaluate the importance of exogenous LH in poor responders undergoing IVF with GnRH antagonists.

DESIGN

Retrospective cohort study.

SETTING

University-based IVF center.

PATIENT(S)

All patients with a history of poor response to ovarian stimulation undergoing IVF with GnRH antagonists between September 2000 and August 2001.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy rates.

RESULT(S)

Two hundred forty GnRH-antagonist cycles were initiated in poor responders. One hundred fifty-three progressed to oocyte retrieval. Seventy-five patients received recombinant FSH (Rec) for ovarian stimulation, and 66 received hMG in combination with Rec. In patients aged <40 years, there were no significant differences in amount and duration of treatment, number of oocytes retrieved, and number of embryos between treatment groups. In patients aged > or =40 years, significantly fewer oocytes were retrieved in groups who received exogenous LH in their stimulation, resulting in significantly fewer fertilized embryos. Implantation and clinical pregnancy rates did not differ by treatment group.

CONCLUSION(S)

In poor responders undergoing IVF with GnRH antagonists, outcomes are comparable whether stimulation is achieved in the presence or absence of supplemental LH. Exogenous LH does not appear to be necessary to achieve pregnancy in these challenging patients and may be detrimental to older patients with a history of poor response.

Serum luteinizing hormone in patients undergoing ovarian stimulation with gonadotropin-releasing hormone antagonists and recombinant follicle-stimulating hormone and its relationship with cycle outcome

The serum LH was determined on days 3, 6, and 8 of stimulation and on the day of hCG in 110 normogonadotropic patients undergoing controlled ovarian hyperstimulation (COH) for IVF induced with GnRH antagonists and recombinant FSH, creating three groups of patients according to Tukey's hinges (percentiles 25 and 75) for each determination. No differences were observed between the number of oocytes recovered or the fertilization, implantation, and pregnancy rates (PR) of the groups, although patients with high serum LH levels during stimulation showed significantly higher serum E2 levels on the day of hCG.

The use of recombinant human LH (lutropin alfa) in the late stimulation phase of assisted reproduction cycles: a double-blind, randomized, prospective study

BACKGROUND

The effect of recombinant human LH (r-hLH; lutropin alfa) in women undergoing controlled ovarian stimulation with recombinant human FSH (r-hFSH) prior to IVF was investigated.

METHODS

After down-regulation with the GnRH agonist, buserelin, 114 normo-ovulatory women (aged 18-37 years) received r-hFSH alone until the lead follicle reached a diameter of 14 mm. Patients were then randomized in a double-blind fashion to receive r-hFSH in addition to r-hLH, 75 IU s.c., or placebo daily for a maximum of 10 days prior to oocyte retrieval and IVF. The primary end-point was the number of metaphase II oocytes.

RESULTS

There were no significant differences between treatment groups for the primary end-point. Serum estradiol concentrations on the day of HCG administration were significantly higher in the group receiving r-hLH plus r-hFSH than in the group receiving r-hFSH alone (P = 0.0001), but there were no significant differences between the groups in dose and duration of r-hFSH treatment required, oocyte maturation, fertilization rate, pregnancy rate and live birth rate.

CONCLUSION

In this patient population, the addition of r-hLH during the late follicular phase of a long GnRH agonist and r-hFSH stimulation cycle provides no further benefit in terms of oocyte maturation or other end-points.

Steroid signalling in the ovarian surface epithelium

Human ovarian surface epithelium (HOSE) undergoes serial injury-repair with each ovulation, which is probably why most ovarian epithelial cancers arise there. Considering the proposed inflammatory aetiology of ovarian cancer, anti-inflammatory steroid signalling might be vital for HOSE regulation. HOSE cells express hydroxysteroid dehydrogenase (HSD) enzymes that undertake prereceptor metabolism of bioinert steroidogenic precursors formed elsewhere in the body. Ovulation-associated cytokines activate anti-inflammatory cortisol from precursor cortisone in HOSE cells owing to up-regulation of the gene encoding 11betaHSD type 1 (HSD11B1) in vitro. Cortisol further enhances its own formation and action through augmentation of cytokine-induced HSD11B1 and glucocorticoid receptor gene expression. Understanding this feed-forward signalling process has implications for the improved diagnosis and treatment of inflammation-associated reproductive disease states such as ovarian cancer.

Specificity and promiscuity of gonadotropin receptors

The dichotomy between hormone recognition by the ectodomain and activation of the G protein by the rhodopsin-like serpentine portion is a well established property of glycoprotein hormone receptors. The specificity barrier avoiding promiscuous activation of the FSH receptor by the high concentration of human chorionic gonadotropin (hCG) prevailing during human pregnancy was thus believed to lie in the ectodomain. In the past two years, mutations responsible for rare spontaneous cases of ovarian hyperstimulation syndromes have partially modified this simple view. Five naturally occurring mutations have been identified which cause an increase in the sensitivity of the FSH receptor to hCG. Surprisingly, these mutations are all located in the serpentine portion of the receptor. In addition to their effect on sensitivity to hCG, they increase sensitivity of the FSH receptor to TSH, and are responsible for activating the receptor constitutively. Together, the available information indicates that the ectodomain and the serpentine domain of the FSH receptor each contribute to the specificity barrier preventing its spurious activation by hCG. While the former is responsible for establishment of binding specificity, the latter introduces a novel notion of functional specificity.

Recent data demonstrate that LH and FSH receptors can constitute functional homo- and heterodimers. This suggests the possibility that in cells co-expressing the two receptors, such as granulosa cells, the heterodimers might be endowed with functional characteristics different from those of each homodimer.

Intrafollicular paracrine communication in the zebrafish ovary: the state of the art of an emerging model for the study of vertebrate folliculogenesis

The development and function of vertebrate ovary are primarily controlled by the gonadotropins, follicle-stimulating hormone (FSH) and luteinizing hormone (LH), from the pituitary. However, most of the activities of FSH and LH are mediated or modulated by a variety of locally produced factors that form an intimate regulatory network within and between the follicles. As a top vertebrate model for genetic and developmental studies, the zebrafish has caught tremendous attention in the past two decades; however, its utility has quickly been extended to other areas including physiology. In the past few years, a variety of peptide growth factors have been identified and characterized in the zebrafish ovary including activin and epidermal growth factor (EGF), and lines of evidence point to the existence of an ovarian network of communication involving these factors. This article provides the state of the art of zebrafish as a model for analyzing ovarian development and its regulation.

Serum luteinizing hormone, follicle-stimulating hormone and oestradiol pattern in women undergoing pituitary suppression with different gonadotrophin-releasing hormone analogue protocols for assisted reproduction

Gonadotrophin-releasing hormone analogues (GnRH-a) are used widely in controlled ovarian stimulation (COS) cycles for assisted reproduction. At present, there is great debate about the influence of exogenous hormone activity on the hypothalamus-pituitary axis following pituitary desensitization. The objective of this comparative study was to investigate the pattern of luteinizing hormone (LH), follicle-stimulating hormone (FSH) and oestradiol in women undergoing ovarian stimulation with different GnRH-a preparations. We retrospectively analysed 201 women, aged between 27 and 43 years, who were referred consecutively to our infertility clinic between January 2002 and January 2003. All women had no endocrinopathies or occult ovarian failure as assessed by day-3 hormone profile. Women were enrolled in one of the following COS protocols: depot triptorelin long protocol (n = 38), buserelin long protocol (n = 101) or buserelin short protocol (n = 62). Recombinant FSH was used to induce ovulation. Treatment was monitored by transvaginal ultrasound scan and serum measurement of FSH, LH and oestradiol. Among the women initially included, 30 had cancelled cycles due to poor ovarian response. Serum LH levels were significantly higher in the short-protocol group compared with the long-protocol groups (p < 0.001). The number of follicles, oocyte yield, number of grade-I embryos and fertilization rate were significantly lower in the short-protocol group than in the long-protocol groups. These findings showed that LH concentrations are significantly higher in women undergoing reversible medical hypophysectomy with a GnRH-a short protocol than in women treated with a long protocol. The hypothesis of an LH ceiling is confirmed.

Evaluation of two doses of recombinant luteinizing hormone supplementation in an unselected group of women undergoing follicular stimulation for in vitro fertilization

OBJECTIVE

To evaluate the efficacy of two doses of recombinant (r)LH, 75 IU (recommended) or 37.5 IU, for follicular stimulation and outcomes in a randomized cohort of IVF patients.

DESIGN

Randomized, prospective analysis.

SETTING

Private hospital incorporating an established IVF center.

PATIENT(S)

Women undergoing IVF who had a body mass index >18 or <35 and no abnormal karyotype, anovulation, oligomenorrhea, or any known endocrinopathy/illness.

INTERVENTION(S)

Pituitary desensitization was achieved with triptorelin (0.1 mg SC), and gonadotropin stimulation was performed with either rFSH alone (group A) or in combination with rLH in one of two doses: 37.5 IU (group B) or 75 IU (group C), daily.

MAIN OUTCOME MEASURE(S)

A range of endocrinologic, embryologic, clinical, and outcome parameters were evaluated.

RESULT(S)

With rLH supplementation there was a significant increase in the incidence of implantation (9% for rFSH only [group A] vs. 11% and 16% with 37.5 IU rLH and 75.0 IU rLH [groups B and C], respectively) and clinical pregnancy (19% vs. 23% and 31%) (P<.01 and P<.04, respectively), whereas there was no difference in the multiple pregnancy rates. There was a significant (P<.001) increase in the total units of rFSH used in proportion to the amount of rLH supplementation (2,645 U vs. 3,475 U and 3,681 U) and in the level of peripheral E(2) on the day of hCG administration (1,049 pg/mL vs. 1,640 pg/mL and 1,226 pg/mL) (P<.001). There was no significant between difference in mean age, numbers of oocytes recovered, basal and downregulation hormone levels, or the incidence of fertilization in the absence or presence of rLH supplementation, but a higher incidence of grade 1 to 2 embryos was observed when rLH was supplemented.

CONCLUSION(S)

After pituitary desensitization, there was an increase in the incidence of implantation, clinical pregnancy, and delivery rates in patients stimulated with rFSH supplemented with rLH.

Expression of CCAAT/enhancer binding proteins alpha and beta in the porcine ovary and regulation in primary cultures of granulosa cells

CCAAT/enhancer binding proteins alpha and beta (CEBPA/ CEBPB) were evaluated in the porcine ovary during the estrous cycle. CEBPB mRNA was present in antral follicles and was significantly increased in healthy corpora lutea (CL), whereas CEBPA mRNA was constitutively expressed in these structures. Both isoforms of CEBPA (42 and 30 kDa) exhibited greater expression in preovulatory follicles, and the 42-kDa isoform increased in CL, whereas the 30-kDa isoform decreased. All major isoforms of CEBPB (38, 34, and 20 kDa) were expressed, with the 34- and 20-kDa isoforms being more abundant in preovulatory follicles and further increased in CL. The effects of FSH and cAMP analogue on the distribution of CEBP isoforms were evaluated in primary cultures of porcine granulosa cells. FSH and 8-Br-cAMP had little stimulatory effect on isoform distribution, but cAMP treatment for 24 h tended to decrease the 30-kDa form of CEBPA and the 34-kDa form of CEBPB. The 34-kDa form of CEBPB was decreased by the protein kinase A inhibitor H89 at 4 h (with FSH treatment), and by both protein kinase A and phosphatidylinositol 3-kinase inhibitors at 24 h of treatment. In transfected granulosa cells, FSH and cAMP analogue stimulated a CEBP consensus sequence-reporter construct that was blocked by H89. These data implicate protein kinase A as the major regulator of CEBPB isoform distribution and CEBP-mediated transactivation in granulosa cells. The differential expression of specific CEBPA/B isoforms observed in maturing follicles and CL may contribute to changes in follicular cell differentiation and increasing steroidogenic capacity.

The effects of reduced oxygen tension on swine granulosa cell

Follicular growth is characterized by an augmented vascularization, possibly driven by a fall in the oxygen supply. The present study was undertaken to investigate the effects of hypoxia on swine granulosa cells. At first, we quantified oxygen partial pressure (pO2) in follicular fluid from different size follicles; the granulosa cells collected from large follicles (>5 mm) were subjected for 18 h to normoxia (19% O2), partial (5% O2) or total hypoxia (1% O2). The effects of these conditions were tested on the main parameters of granulosa cell function, steroidogenesis and cell proliferation, and on vascular endothelial growth factor (VEGF), nitric oxide (NO) and superoxide anion (O2-) production. Oxygen tension in follicular fluid was negatively related to follicular size, pointing out a gradual reduction during follicular growth. Severe hypoxic conditions determined a reduction of both 17beta estradiol and progesterone production, while partial hypoxia did not seem to affect them. Hypoxia increased VEGF as well as O2- production in swine granulosa cells without impairing cell growth; in addition, it decreased NO output. We may conclude that physiological hypoxia could play a pivotal role in the follicular angiogenic process stimulating VEGF synthesis by granulosa cells. ROS are possibly involved in hypoxic signalling.

The Roles of Vitamin A for Cytoplasmic Maturation of Bovine Oocytes

Vitamin A is one of the micronutrients which have been implicated in cattle reproduction. In cattle, ingested vitamin A, mainly as beta-carotene (BC) from forages and retinol ester from formula feed, is metabolized and transported to the oocytes and cumulus-granulosa cells in ovarian follicles through binding to various interacting molecules. The active form of vitamin A, retinoic acid (RA), functions as a regulator of gene expression in these targets. Early research showed the positive effects of vitamin A supplementation on bovine fertility in artificial insemination, and several studies on effects of vitamin A metabolites used in other artificial reproductive techniques (ART), including superovulation, ovum pick up, and in vitro maturation culture have provided evidence for the specific roles of vitamin A in oocyte cytoplasmic maturation (acquisition of developmental competence of oocytes during their meiotic maturation period for the embryonic development after fertilization). BC may enhance cytoplasmic maturation by its antioxidant properties which cannot be replaced by RA. Furthermore, RA may promote cytoplasmic maturation of bovine oocytes via its modulatory effects on the gene expression of gonadotrophin receptors, midkine, cyclooxygenase-2, and nitric oxide synthase in cumulus-granulosa cells.

Proliferation of rat granulosa cells during the periovulatory interval

Granulosa cell proliferation during luteinization and terminal differentiation has historically been assumed to decline rapidly after an ovulatory stimulus. In contrast, terminal differentiation in other cell types has recently been associated with a transient increase in proliferation, suggesting that this may occur in the ovarian follicle. The goal of the current study was to test the hypothesis that an ovulatory stimulus to rats results in additional granulosa cell proliferation before cell cycle arrest. Immature rats were given a single injection of pregnant mare serum gonadotropin (PMSG) followed by human chorionic gonadotropin (hCG) to initiate periovulatory events. The proportion of granulosa cells in S phase did not change until 12 h after hCG, although the majority of the post-hCG proliferation was localized to cumulus granulosa cells for up to 10 h after hCG. The expression of cyclin D2 mRNA did not decline until 12 h after hCG, although both cyclin-dependent kinase (Cdk)4 and Cdk6 mRNA increased at 6 h. Protein levels of cyclin D2 and Cdk4 did not change as a result of hCG, whereas cyclin E increased 6 h after hCG. Kinase activity of Cdk2 dropped markedly by 4 h after hCG, but a slight increase in activity was evident 6-8 h after hCG. These data suggest that cumulus granulosa cells continue to proliferate for up to 10 h after an ovulatory stimulus, possibly via cyclin E/Cdk2. It is concluded that proliferation is maintained in granulosa cells in the proximity of the oocyte during luteinization of the rat follicle.

Cryopreservation of pig granulosa cells: effect of FSH addition to freezing medium

We cryopreserved swine granulosa cells by a slow cooling rate system; FSH was added to the freezing medium to test its effectiveness in protecting the cells. After thawing, proliferative activity, viability, steroidogenesis and apoptosis were tested; moreover, we determined heat shock protein (HSP70) production, to investigate the recovery from stress and superoxide dismutase (SOD) and catalase activity to evaluate a possible impairment of the antioxidant pathway. E2 production was enhanced by cryopreservation in particular with FSH; on the contrary, P4 production was inhibited by the freezing process in particular without FSH. Only the higher FSH concentration (10 ng/ml) stimulated steroid secretion in freshly collected cells; P4 production by cells cryopreserved in the presence and in absence of FSH was increased by both 5 and 10 ng/ml while the lowest concentration was effective in stimulating E2 production only when FSH was added to freezing medium. Freezing did not modify proliferative activity, while apoptosis was higher in frozen than in fresh cells. HSP70 production was lower in cells cryopreserved in presence of FSH, whose antioxidant metabolism was also conserved: SOD and catalase activities were similar to control. In conclusion, cryopreservation does not seem to markedly affect granulosa cells, in particular if they are frozen in presence of FSH; the gonadotrophin somehow improves their performances after thawing, probably stimulating E2 production and the antioxidant metabolism.

PCOS: an ovarian disorder that leads to dysregulation in the hypothalamic–pituitary–adrenal axis?

This review focuses on the role of the ovaries in the pathogenesis of the polycystic ovarian syndrome. In particular, the failure of follicular development, hypothalamo-pituitary dysregulation, alterations in adrenal steroid output and derangement of intermediary metabolism are discussed in the context of the ovaries. It is concluded that the central and adrenal alterations associated with PCOS are unlikely to be primary but rather are secondary to the events within the ovary.

Development and application of a rat ovarian gene expression database

The pituitary gonadotropins play a key role in follicular development and ovulation through the induction of specific genes. To identify these genes, we have constructed a genome-wide rat ovarian gene expression database (rOGED). The database was constructed from total RNA isolated from intact ovaries, granulosa cells, or residual ovarian tissues collected from immature pregnant mare serum gonadotropin (PMSG)/human chorionic gonadotropin-treated rats at 0 h (no PMSG), 12 h, and 48 h post PMSG, as well as 6 and 12 h post human chorionic gonadotropin. The total RNA was used for DNA microarray analysis using Affymetrix Rat Expression Arrays 230A and 230B (Affymetrix, Santa Clara, CA). The microarray data were compiled and used for display of individual gene expression profiles through specially developed software. The final rOGED provides immediate analysis of temporal gene expression profiles for over 28,000 genes in intact ovaries, granulosa cells, and residual ovarian tissue during follicular growth and the preovulatory period. The accuracy of the rOGED was validated against the gene profiles for over 20 known genes. The utility of the rOGED was demonstrated by identifying six genes that have not been described in the rat periovulatory ovary. The mRNA expression patterns and cellular localization for each of these six genes (estrogen sulfotransferase, synaptosomal-associated protein 25 kDa, runt-related transcription factor, calgranulin B, alpha1-macroglobulin, and MAPK phosphotase-3) were confirmed by Northern blot analyses and in situ hybridization, respectively. The current findings demonstrate that the rOGED can be used as an instant reference for ovarian gene expression profiles, as well as a reliable resource for identifying important yet, to date, unknown ovarian genes.

Randomized trial to compare the effect of recombinant human FSH (follitropin alfa) with or without recombinant human LH in women undergoing assisted reproduction treatment

Women undergoing intracytoplasmic sperm injection (ICSI) for male factor infertility were randomly assigned to receive ovarian stimulation in a long agonist protocol with a combination of recombinant human FSH (r-hFSH; Gonal-F) and recombinant human LH (r-hLH; Luveris) (n = 212) starting on day 6 of FSH stimulation until human chorionic gonadotrophin (HCG) at a daily fixed dose of 150 IU r-hLH, or with r-hFSH alone (n = 219). There was no significant difference in the number of metaphase II oocytes retrieved (10.3 versus 10.4) in patients treated with r-hFSH and r-hLH versus r-hFSH alone; however, more embryos were transferred in the LH-supplemented group (2.9 versus 2.8, P = 0.037). Overall, the implantation rates were 22.9 versus 27.0% in patients treated with r-hFSH and r-hLH versus with r-hFSH alone respectively (NS). The respective numbers of MII oocytes retrieved in patients <35 or >or=35 years were 11 versus 8.3 (P = 0.010) for patients treated with r-hFSH alone, and 10.7 versus 9.3 (NS) for those given supplemental r-hLH (150 IU) from day 6. Implantation rates in patients <35 years treated with r-hFSH were higher (30.7%) than those receiving r-hFSH and r-hLH, (23.5%) (P = 0.068). In patients >or=35 years, the implantation rates were 21.7% for those patients supplemented with 150 IU r-hLH from day 6 of stimulation versus 15.7% when treated with FSH alone (NS). Younger patients therefore do not seem to benefit from an LH-supplemented ovarian stimulation protocol, but women >or=35 years undergoing assisted reproduction may benefit from using r-hLH in addition to r-hFSH.

Energy Substrate Metabolism of Mouse Cumulus-Oocyte Complexes: Response to Follicle-Stimulating Hormone Is Mediated by the Phosphatidylinositol 3-Kinase Pathway and Is Associated with Oocyte Maturation1

Successful in vitro maturation (IVM) of oocytes obtained from medium-sized antral follicles could avoid the need for superovulation for in vitro fertilization. The wide range of doses of FSH used in IVM prompted us to study the effect of varying concentrations of FSH on the dynamics of nutrient uptake and production by individual maturing mouse cumulus-oocyte complexes (COCs). COCs isolated from the antral follicles of unprimed, prepubertal B6CBF(1) mice were cultured individually in increasing concentrations of FSH (0-2000 ng/ml). Following culture, pyruvate, glucose, and lactate uptake or production by individual complexes were noninvasively assessed and compared with the stage of nuclear maturation of the enclosed oocyte. FSH significantly increased oocyte maturation and produced a two- to threefold increase in glucose uptake and lactate production by COCs in which the enclosed oocyte completed maturation. In these COCs, pyruvate was taken up under control conditions but was produced in progressively higher quantities in increasing concentrations of FSH. In COCs where the oocyte failed to complete maturation, pyruvate was taken up (rather than produced) and glucose uptake and lactate production were lower and unaffected by the presence or absence of FSH. This suggests that there is dialogue between cumulus cells and the maturing oocyte that influences FSH responsiveness and substrate metabolism of the whole COC. Finally, inhibition of FSH-stimulated glucose uptake by the PI3-kinase inhibitor LY294002 and the finding of GLUT4 protein in granulosa cells suggest that FSH increases glucose uptake by PI3-kinase-mediated translocation of GLUT4 to the granulosa cell membrane.

Androgen receptor mRNA expression in the bovine ovary

Previous studies have shown that androgen receptor (AR) is expressed in granulosa cells of healthy, growing ovarian follicles in rats and primates. However, AR expression in the bovine ovary has not been examined. Therefore, a 346-base pair segment of the bovine AR was cloned and sequenced. Using a ribonuclease protection assay, AR expression was detected in total RNA from bovine ovarian cortex. Expression (absence or presence) of AR mRNA was detected by in situ hybridization in bovine ovarian cortex. Follicles (n = 32) were classified as follows: type 1 (1 layer of flattened granulosa cells), type 2 (1-1.5 layers of cuboidal granulosa cells), type 3 (2-3 layers of granulosa cells), type 4 (4-6 layers of cuboidal granulosa cells and formation of thecal layer), and type 5 (>6 layers of cuboidal granulosa cells, defined theca layer, and antrum formation). Frequency of AR mRNA expression increased (P < 0.001) as follicles entered the growing pool. Expression of AR mRNA was absent in type 1 follicles (n = 8), but present in the granulosa cells of 41% of type 2 follicles (n = 12). In types 3-5 follicles, AR mRNA expression was present in granulosa cells of 100% of follicles examined (n = 4, 4, and 4, respectively) and was greater than type 1 follicles (P = 0.002). These data provide evidence of AR mRNA expression in bovine follicles and suggest that AR mRNA increases during early follicle development.

Retention of estradiol negative feedback relationship to LH predicts ovulation in response to caloric restriction and weight loss in obese patients with polycystic ovary syndrome

The present study tests the hypothesis that specific endocrine, metabolic, and anthropometric features distinguish obese women with polycystic ovary syndrome (PCOS) who resume ovulation in response to calorie restriction and weight loss from those who do not. Fifteen obese (body mass index 39 +/- 7 kg/m(2)) hyperandrogenemic oligoovulatory patients undertook a very low calorie diet (VLCD), wherein each lost > or =10% of body weight over a mean of 6.25 mo. Body fat distribution was quantitated by magnetic resonance imaging. Hormones were measured in the morning at baseline, after 1 wk of VLCD, and after 10% weight loss. To monitor LH release, blood was sampled for 24 h at 10-min intervals before intervention and after 7 days of VLCD. Responders were defined a priori as individuals exhibiting two or more ovulatory cycles in the course of intervention, as corroborated by serum progesterone concentrations > or =18 nmol/l followed by vaginal bleeding. At baseline, responders had a higher sex hormone-binding globulin (SHBG) concentration but were otherwise indistinguishable from nonresponders. Body weight, the size of body fat depots, and plasma insulin levels declined to a similar extent in responders and nonresponders. Also, SHBG increased, and the free testosterone index decreased comparably. However, responders exhibited a significant decline of circulating estradiol concentrations (from 191 +/- 82 to 158 +/- 77 pmol/l, means +/- SD, P = 0.037) and a concurrent increase in LH secretion (from 104 +/- 42 to 140 +/- 5 U.l(-1).day(-1), P = 0.006) in response to 7 days of VLCD, whereas neither parameter changed significantly in nonresponders. We infer that evidence of retention of estradiol-dependent negative feedback on LH secretion may forecast follicle maturation and ovulation in obese patients with PCOS under dietary restriction.

Tumor necrosis factor alpha (TNF) increases granulosa cell proliferation: dependence on c-Jun and TNF receptor type 1

TNF alpha has significant in vitro effects on steroidogenesis and folliculogenesis and reproductive alterations occur in TNF receptor type 1 (TNFR1) knockout mice. The present study investigated the effect of in vitro TNF on granulosa cell proliferation from immature mice at 28 d of age, with emphasis on intracellular signaling that regulates granulosa cell proliferation. TNF dose dependently increased granulosa cell proliferation and the proto-oncogene c-Jun protein. However, other Jun family members such as JunD was expressed constitutively and JunB was not expressed. In vitro TNF did not increase c-Jun and proliferation in granulosa cells from TNFR1 knockout mice. The time course of TNF-induced c-Jun revealed biphasic patterns of short-term (3 h) and long-term (24 h) induction. The time courses of Ser63- and Ser73-phospho c-Jun coincided with changes in total c-Jun. Among MAPK cascades, stress-activated protein kinase/c-Jun-NH(2)-teminal kinase signaling was increased transiently in TNF-treated cells, whereas p38MAPK and ERK1 and 2 were not changed. In addition, overexpression of nuclear factor-kappa B and addition of ceramide and 8-bromo-cAMP did not increase c-Jun or proliferation. Antisense oligonucleotides for c-Jun blocked cell proliferation induced by TNF. In conclusion, the above results demonstrate that TNF increased c-Jun by activating stress-activated protein kinase/c-Jun-NH(2)-teminal kinase signaling via TNFR1 in mouse granulosa cells, and the induced c-Jun resulted in increased cell proliferation.

Follicle-stimulating hormone activation of hypoxia-inducible factor-1 by the phosphatidylinositol 3-kinase/AKT/Ras homolog enriched in brain (Rheb)/mammalian target of rapamycin (mTOR) pathway is necessary for induction of select protein markers of follicular differentiation

We sought to elucidate the role of AKT in follicle-stimulating hormone (FSH)-mediated granulosa cell (GC) differentiation. Our results define a signaling pathway in GCs whereby the inactivating phosphorylation of tuberin downstream of phosphatidylinositol (PI) 3-kinase/AKT activity leads to Rheb (Ras homolog enriched in brain) and subsequent mTOR (mammalian target of rapamycin) activation. mTOR then stimulates translation by phosphorylating p70 S6 kinase and, consequently, the 40 S ribosomal protein S6. Activation of this pathway is required for FSH-mediated induction of several follicular differentiation markers, including luteinizing-hormone receptor (LHR), inhibin-alpha, microtubule-associated protein 2D, and the PKA type IIbeta regulatory subunit. FSH also promotes activation of the transcription factor hypoxia-inducible factor-1 (HIF-1). FSH-stimulated HIF-1 activity is inhibited by the PI 3-kinase inhibitor LY294002, the Rheb inhibitor FTI-277 (farnesyltransferase inhibitor-277), and the mTOR inhibitor rapamycin. Finally, we find that the FSH-mediated up-regulation of reporter activities for LHR, inhibin-alpha, and vascular endothelial growth factor is dependent upon HIF-1 activity, because a dominant negative form of HIF-1alpha interferes with the up-regulation of these genes. These results show that FSH enhances HIF-1 activity downstream of the PI 3-kinase/AKT/Rheb/mTOR pathway in GCs and that HIF-1 activity is necessary for FSH to induce multiple follicular differentiation markers.

Comparative responses of molluscs and fish to environmental estrogens and an estrogenic effluent

It is now well established that there is a diverse array of chemical discharged into the environment that can mimic or antagonise the action of hormones. These endocrine-disrupting chemicals (EDCs) can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife that are exposed to them. As yet, however, there is little information on the relative sensitivities of different wild life groups to these chemicals and/or mixtures of them (e.g. estrogenic effluents) and hence, there are fundamental shortfalls in our knowledge of the ecological chemicals (17alpha-ethinylestradiol; EE2, bisphenol-A, and 4-tert octylphenol) and a mixture containing these chemicals (treated sewage effluent) on embryo production in the prosobranch mollusc, Potamopyrgus antipodarum, were studied and compared with the effects of EE2 and the same estrogenic effluent on vitellogenin induction and/or egg production in various species of freshwater fish (fathead minnow; Pimaphales promelas, rainbow trout (Oncorhynchus mykiss); Cyprinus carpio, carp; Cyprinus carpio). The lab-based studies demonstrated that all of the tested chemicals (known to be estrogenic and to cause reproductive effects in fish) also affected embryo production in P. antipodarum. Furthermore, exposure to EE2 induced similar reproductive responses in the snails as in the fathead minnow (Pimephales promelas), stimulating egg/embryo production at low doses (up to 1 ng/l in the minnow and 25 ng/l in the snail) and causing inhibitory effects at higher doses. A similar pattern of embryo production occurred in P. antipodarum when it was exposed to a graded concentration of treated sewage effluent containing mixtures of estrogenic EDCs and hence, the total number of new embryos produced by the snails increased steadily over the 9 week exposure period in treated snails. Plasma vitellogenin concentrations in two species of male fish (the rainbow trout and the carp) also increased over the same time period. These data indicate that both the nature of the response and the relative sensitivities to environmental estrogens in P. antipodarum and three different fish species fish are comparable. P. andtipodarum is thus, potentially a sensitive test organism for assessing estrogenicity of chemicals with a relevance to their activity in vertebrates.

The murine winged-helix transcription factor Foxl2 is required for granulosa cell differentiation and ovary maintenance

Human Blepharophimosis/ptosis/epicanthus inversus syndrome (BPES) type I is an autosomal dominant disorder associated with premature ovarian failure (POF) caused by mutations in FOXL2, a winged-helix/forkhead domain transcription factor. Although it has been shown that FOXL2 is expressed in adult ovaries, its function during folliculogenesis is not known. Here, we show that the murine Foxl2 gene is essential for granulosa cell differentiation and ovary maintenance. In Foxl2(lacZ) homozygous mutant ovaries granulosa cells do not complete the squamous to cuboidal transition leading to the absence of secondary follicles and oocyte atresia. We further demonstrate that activin-betaA and anti-Mullerian inhibiting hormone expression is absent or strongly diminished in Foxl2(lacZ) homozygous mutant ovaries. Unexpectedly, two weeks after birth most if not all oocytes expressed Gdf9 in Foxl2(lacZ) homozygous mutant ovaries, indicating that nearly all primordial follicles have already initiated folliculogenesis at this stage. This activation, in the absence of functional granulosa cells, leads to oocyte atresia and progressive follicular depletion. In addition to providing a molecular mechanism for premature ovarian failure in BPES, these results suggest that granulosa cell function is not only crucial for oocyte growth but also to maintain follicular quiescence in vivo.

Mutant mouse models and their contribution to our knowledge of corpus luteum development, function and regression

The corpus luteum is a unique organ, which is transitory in nature. The development, maintenance and regression of the corpus luteum are regulated by endocrine, paracrine and autocrine signaling events. Defining the specific mediators of luteal development, maintenance and regression has been difficult and often perplexing due to the complexity that stems from the variety of cell types that make up the luteal tissue. Moreover, some regulators may serve dual functions as a luteotropic and luteolytic agent depending on the temporal and spatial environment in which they are expressed. As a result, some confusion is present in the interpretation of in vitro and in vivo studies. More recently investigators have utilized mutant mouse models to define the functional significance of specific gene products. The goal of this mini-review is to identify and discuss mutant mouse models that have luteal anomalies, which may provide some clues as to the significance of specific regulators of corpus luteum function.

Comparative responses of molluscs and fish to environmental estrogens and an estrogenic effluent

It is now well established that there is a diverse array of chemicals discharged into the environment that can mimic or antagonise the action of hormones. These endocrine-disrupting chemicals (EDCs) can thus interact with physiological systems and cause alterations in development, growth and reproduction in wildlife that are exposed to them. As yet, however, there is little information on the relative sensitivities of different wildlife groups to these chemicals and/or mixtures of them (e.g. estrogenic effluents) and hence, there are fundamental shortfalls in our knowledge of the ecological importance of endocrine disruption in wildlife. In this study, the effects of exposure to individual estrogenic chemicals (17alpha-ethinylestradiol; EE2, bisphenol-A, and 4-tert octylphenol) and a mixture containing these chemicals (treated sewage effluent) on embryo production in the prosobranch mollusc, Potamopyrgus antipodarum, were studied and compared with the effects of EE2 and the same estrogenic effluent on vitellogenin induction and/or egg production in various species of freshwater fish (fathead minnow; Pimaphales promelas, rainbow trout (Oncorhynchus mykiss); Cyprinus carpio, carp; Cyprinus carpio). The lab-based studies demonstrated that all of the tested chemicals (known to be estrogenic and to cause reproductive effects in fish) also affected embryo production in P. antipodarum. Furthermore, exposure to EE2 induced similar reproductive responses in the snails as in the fathead minnow (Pimephales promelas), stimulating egg/embryo production at low doses (up to 1 ng/l in the minnow and 25 ng/l in the snail) and causing inhibitory effects at higher doses. A similar pattern of embryo production occurred in P. antipodarum when it was exposed to a graded concentration of treated sewage effluent containing mixtures of estrogenic EDCs and hence, the total number of new embryos produced by the snails increased steadily over the 9 weeks exposure period in treated snails. Plasma vitellogenin concentrations in two species of male fish (the rainbow trout and the carp) also increased over the same time period. These data indicate that both the nature of the response and the relative sensitivities to environmental estrogens in P. antipodarum and three different fish species fish are comparable. P. antipodarum is thus, potentially a sensitive test organism for assessing estrogenicity of chemicals with a relevance to their activity in vertebrates.

Morphodynamics of the follicular-luteal complex during early ovarian development and reproductive life

Female reproductive activity depends upon cyclic morphofunctional changes of the ovarian tissue during the female's fertile period, but the primum movens of an active gonadal rearrangement can be found from early phases of embryo development. To offer a basic account of the main steps of ovarian dynamics, we review the morphofunctional behavior of the follicular-luteal complex in an integrated study using light microscopy and transmission and scanning electron microscopy as well as through the use of numerous drawings. Particular emphasis is given to some reproductive aspects including (1) germ-somatic cell relationships and onset of folliculogenesis during early gonadal development; (2) follicular development and oocyte-follicle cell associations through adult folliculogenesis, finally leading to ovulation; (3) morphodynamics of corpus luteum formation, development, and regression, and (4) degenerative processes involving germ and somatic cells. The results reported, many of which originated in our laboratory, arise from some experiments on laboratory mammals but mostly from a large selection of human specimens. The data obtained are integrated and correlated with classic reports as well as with current views. Crucial biochemical, histophysiological, and clinical aspects are also emphasized.

Impact of carbohydrate heterogeneity in function of follicle-stimulating hormone: studies derived from in vitro and in vivo models

Carbohydrates attached to the protein core of glycoprotein hormones influence a number of intracellular and extracellular processes. As with other members of the glycoprotein hormone family, FSH is produced and released as an array of isoforms that differ from each other in the structure of their oligosaccharide attachments. In this review, we discuss how carbohydrate heterogeneity can impact on FSH action in different in vitro and in vivo systems. We present evidence for diverse effects of distinct charge isoforms at the target cell level, including differential and unique effects on various end responses, and discuss how the use of multiple cell-type assays has allowed identification of some specific effects of FSH isoforms on different cell populations and follicle compartments as well as oocyte maturation. Finally, we discuss recent information on the ability of naturally occurring and laboratory manufactured FSH isoforms to evoke particular effects on granulosa cell function and ovarian follicular maturation in vivo. Such studies have provided evidence that the type(s) of FSH signal delivered may in fact regulate distinct biological outcomes irrespective or in addition to outcomes dictated solely by clearance rate differences.

Ovarian responses to recombinant FSH or HMG in normogonadotrophic women following pituitary desensitization by a depot GnRH agonist for assisted reproduction

At present, there is considerable debate about the utility of supplemental LH in assisted reproduction treatment. In order to explore this, the present authors used a depot gonadotrophin-releasing hormone agonist (GnRHa) protocol combined with recombinant human FSH (rhFSH) or human menopausal gonadotrophin (HMG) in patients undergoing intracytoplasmic sperm injection (ICSI). The response to either rhFSH (75 IU FSH/ampoule; group rhFSH, 25 patients) or HMG (75 IU FSH and 75 IU LH/ampoule; group HMG, 25 patients) was compared in normo-ovulatory women suppressed with a depot triptorelin injection and candidates for ICSI. A fixed regimen of 150 IU rhFSH or HMG was administered in the first 14 days of treatment. Treatment was monitored with transvaginal pelvic ultrasonographic scans and serum measurement of FSH, LH, oestradiol, androstenedione, testosterone, progesterone, inhibin A, inhibin B and human chorionic gonadotrophin (HCG) at 2-day intervals. Although oestradiol serum concentrations on the day of HCG injection were similar, both the duration of treatment and the per cycle gonadotrophin dose were lower in group HMG. In the initial 16 days of gonadotrophin treatment, the area under the curve (AUC) of LH, oestradiol, androstenedione and inhibin B were higher in group HMG; no differences were seen for the remaining hormones measured, including the inhibin B:inhibin A ratio. The dynamics of ovarian follicle development during gonadotrophin treatment were similar in both study groups, but there were more leading follicles (>17 mm in diameter) on the day of HCG injection in the rhFSH group. The number of oocytes, mature oocytes and good quality zygotes and embryos obtained were significantly increased in the rhFSH group. It is concluded that in IVF patients undergoing pituitary desensitization with a depot agonist preparation, supplemental LH may be required in terms of treatment duration and gonadotrophin consumption. However, both oocyte, embryo yield and quality were significantly higher with the use of rhFSH.

Pregnancy after administration of high dose recombinant human LH alone to support final stages of follicular maturation in a woman with long-standing hypogonadotrophic hypogonadism

Traditionally, the roles of LH in folliculogenesis have been considered to be limited to stimulating theca cells androgen production, triggering ovulation and supporting the corpus luteum. However, in the late stages of follicle development, granulosa cells become receptive to LH stimulation and LH becomes capable of exerting its actions on both theca cells and granulosa cells. Thus, it has been postulated that once an appropriate (i.e. LH-responsive) stage of follicular development has been achieved in response to treatment with FSH, there are theoretical grounds for reducing or completely withdrawing FSH and maintaining tonic stimulation of the dominant follicle with exogenous LH. This hypothesis was tested in a woman with long-standing hypogonadotrophic hypogonadism, which is the best and only true model to investigate correctly any LH hypothesis. Ovulation induction treatment was carried out with daily s.c. injections of 150 IU recombinant human FSH (rhFSH) (increased to 225 IU daily on stimulation day 15) and 375 IU recombinant human LH (rhLH). When a 14-mm follicle was identified on stimulation day 26, rhFSH was discontinued and from treatment days 26 to 29 the patient was given only rhLH at the above-mentioned dose of 375 IU/day. On treatment day 30, the single dominant follicle measured 22 mm in diameter and oestradiol serum concentration was 148 pg/ml. Thus, an injection of 10,000 IU i.m. human chorionic gonadotrophin was given and sexual intercourse was advised. The patient conceived and a viable singleton intrauterine pregnancy was obtained.

Reproductive adaptations to a large-brained fetus open a vulnerability to anovulation similar to polycystic ovary syndrome

During the ovarian or menstrual cycle, prior to ovulation, many female primates exhibit a relatively prolonged follicular phase and terminate the postovulatory luteal phase with menstrual bleeding. The prolonged follicular phase is a trait that distinguishes primate from nonprimate species. It enables extended estrogen-induced proliferation and growth of the uterine endometrium prior to progesterone-induced maturation during the luteal phase to accommodate a potential pregnancy with a rapidly invading placenta. Progressive development of both an extended duration of estrogen-induced, preimplantation endometrial proliferation and a rapidly invading placenta across the Primate order may well have been necessary to accommodate differentiation and growth of an increasingly large fetal brain. Prolongation of the follicular phase in primates has also led to the isolation of the final stages of follicle selection (growth deviation of the dominant follicle from its contemporaries) solely within the follicular phase and thus outside the protection of luteal phase progesterone inhibition of pituitary luteinizing hormone (LH) secretion. Such primate reproductive characteristics put the latter stages of ovarian follicle selection at risk of exposure to excessive pituitary secretion of LH. Excessive secretion of LH during follicle selection could result not only in impaired follicle development, excessive ovarian androgen secretion, and ovulation failure, but also in excessive estrogenic stimulation of the uterine endometrium without intervening menstrual periods. Such reproductive abnormalities are all found in a single, prevalent infertility syndrome afflicting women in their reproductive years: polycystic ovary syndrome (PCOS). We propose that successful female reproductive adaptations to accommodate the growth demands of large-brained primate fetuses have facilitated a particular vulnerability of higher primates to hypergonadotropic disruption of ovulatory function, as found in PCOS.

Impact of growth hormone resistance on female reproductive function: new insights from growth hormone receptor knockout mice

We examined multiple aspects of reproductive function in growth hormone receptor gene knockout (GHR-KO) and normal mice to clarify the role of growth hormone in female reproduction. In adult animals, estrous cycle duration was comparable in all mice housed individually but was significantly longer in group-housed GHR-KO females. Histological evaluation of ovaries of adult females at estrus showed that the numbers of preovulatory follicles and corpora lutea were significantly reduced in GHR-KO mice, as was the plasma estradiol level. The number of atretic preovulatory follicles was reduced in GHR gene-ablated animals. Although reverse transcription polymerase chain reaction analysis revealed reduced ovarian insulin-like growth factor I (IGF-I) mRNA expression in GHR-KO females, the expression of several steroidogenic enzyme mRNAs did not differ between groups. The numbers of active corpora lutea and uterine implantation sites were reduced in GHR-KO females at Day 7 of gestation. When young females were mated to normal males, latency to first mating and age of the female at first mating were significantly delayed in GHR-KO females, but maternal age at first conception was similar between groups. Significantly fewer virgin GHR-KO females exhibited pseudopregnancies when initially placed with vasectomized normal males than did normal female counterparts. Growth hormone resistance and IGF-I insufficiency negatively impacted 1) follicular development/ovulation rate, 2) sexual maturation, 3) production of and responsiveness to pheromonal signals, and 4) the ability of virgin females to respond to coitus by activation of luteal function. Although GHR-KO female mice are fertile, they exhibit quantitative deficits in various parameters of reproductive function.

Cell-specific distribution of progesterone receptors in the bovine ovary

This study describes the localization of progesterone receptors (PR) in the bovine ovary. Ovaries were obtained from 11 non-pregnant and two pregnant cows. Progesterone receptors were visualized by immunohistochemistry on paraffin sections. Nuclear staining for PR was observed in cells of the follicles, corpora lutea, theca layers, surface epithelium, tunica albuginea, and in superficial and deep stroma cells. No staining was noticed in apoptotic bodies of atretic follicles. Expression of PR in follicle cells indicates an intrafollicular role of progesterone. The higher expression in thecal cells compared with follicle cells indicates that thecal cells mediate some effects of progesterone on the follicular development. Superficial stroma cells showing high expression might have a similar influence on primordial and primary follicles. In general, luteal cells had a lower expression than follicle cells, which may be explained by the down-regulatory effect of locally produced progesterone. The lower expression in luteal cells during pregnancy can be due to the longer life span of this corpus luteum and concomitant degeneration of its PR. The high and rather constant expression of PR in cells of the surface epithelium remains to be elucidated.

Evidence of a role for the INK4 family of cyclin-dependent kinase inhibitors in ovarian granulosa cell tumors

Granulosa cell tumors (GCTs) of the ovary are relatively rare and account for <5% of all ovarian cancers. The molecular pathogenesis of these tumors is not well understood. We tested the hypothesis that cyclin-dependent kinase inhibitors, specifically the inhibitors of the cyclin-dependent kinase 4 (INK4) family, are targets for altered gene expression in GCTs. The status of RB1, INK4A, INK4B, INK4C, INK4D, and ARF in 13 adult and 2 juvenile ovarian GCTs was determined by reverse transcription-polymerase chain reaction of total RNA and exon-specific sequencing of genomic DNA. Tumors showing loss of INK4A expression were assayed further by exon-deletion analysis and methylation-specific PCR. None of the juvenile tumors demonstrated altered expression, but 7/12 (58%) adult GCTs lacked expression of INK4A, INK4B, or both. In one of these cases, we noted a homozygous deletion of the INK4A locus, and in the remaining tumors we found hypermethylation of the promoter region, a mechanism that can lead to gene inactivation. These data support a role for the INK4 family of CDK inhibitors in the biology of GCTs.

Treatment of the infertile patient with polycystic ovarian syndrome

Polycystic ovarian syndrome is associated with infertility due to anovulation caused by this disorder. Many treatments can increase both ovulation and fertility rates in these women. This is a comprehensive review of the literature, with an emphasis on randomized controlled trials of the medical and surgical treatment options for women with polycystic ovarian syndrome and infertility. Both standard and novel treatments are addressed. In the past, clomiphene citrate was the first-line medical treatment for subfertility in these women, followed by gonadotropins with or without gonadotropin releasing-hormone agonists for those women with clomiphene-resistance. Surgical treatments such as ovarian drilling were occasionally added to these regimens. The introduction of the insulin-sensitizing agents as adjuvants to clomiphene citrate and gonadotropins has changed the treatment strategy. The evidence in support of this change will be discussed. Data on the use of glucocorticoids, opioid receptor antagonists, and antiandrogens as adjuvants to standard therapies, as well as surgical treatments such as wedge resection and ovarian drilling will also be discussed. Based upon the evidence, medical treatment remains the primary therapy for women with this syndrome, especially in light of the recent introduction of insulin-sensitizing agents to the treatment armamentarium. These drugs have allowed us to develop less aggressive therapies that are safer and easier for women to utilize, and may in the future become the primary treatment for women with this syndrome.

TARGET AUDIENCE

Obstetricians & Gynecologists, Family Physicians Learning Objectives: After completion of this article, the reader will be able to explain the pathophysiology of PCOS, to list the factors that predispose women to develop PCOS, and to outline the treatment regiments for PCOS-associated infertility.

Stimulation of apoptosis in human granulosa cells from in vitro fertilization patients and its prevention by dexamethasone: involvement of cell contact and bcl-2 expression

Human granulosa cells obtained from in vitro fertilization patients are highly luteinized, but can still be stimulated by LH/cAMP for production of progesterone. This stimulation involved enhancement of apoptosis. Incubation of the cells with dexamethasone (Dex) reduced the apoptotic incidence compared with nontreated cells and completely abolished the increase in apoptosis stimulated by LH or forskolin, concomitantly with a pronounced increase in progesterone production. Organization of the actin cytoskeleton was dramatically reduced after LH/forskolin stimulation. In contrast, Dex prevented disorganization of the actin filament networks. LH and forskolin also decreased the organization of gap junctions, which could be prevented by Dex. However, the intracellular level of connexin 43 was elevated in the presence of LH, forskolin, and Dex. Endogenous levels of the survival gene protein Bcl-2 were significantly elevated in all cultures treated with Dex compared with either nonstimulated cultures or cultures stimulated with LH and forskolin. Our data suggest that LH/cAMP can stimulate steroidogenesis even during the initial stage of apoptosis of human granulosa cells, whereas Dex, which blocks apoptosis, could further elevate progesterone production. Moreover, the integrity of gap junctions and the actin cytoskeleton as well as elevated levels of Bcl-2 may play an important role in the suppression of apoptosis of human granulosa cells.

Is luteinizing hormone needed for optimal ovulation induction?

The role of luteinizing hormone in the natural menstrual cycle is not disputed. There are, however, a variety of opinions regarding the potential role of exogenous luteinizing hormone in ovulation induction and whether it is actually needed. The recent introduction into clinical practice of recombinant gonadotropins has been paralleled by recent advances in the knowledge of the endocrine and paracrine mechanisms that regulate human folliculogenesis. On this basis, this review analyses whether or not all patients need luteinizing hormone for follicular growth stimulation. In addition, new opportunities for improved treatment are considered as a result of the availability of recombinant human luteinizing hormone both in patients with ovulatory disorders and those undergoing multiple follicular development for assisted reproduction.

Cell-specific distribution of progesterone receptors in the bovine ovary

This study describes the localization of progesterone receptors (PR) in the bovine ovary. Ovaries were obtained from 11 non-pregnant and two pregnant cows. Progesterone receptors were visualized by immunohistochemistry on paraffin sections. Nuclear staining for PR was observed in cells of the follicles, corpora lutea, theca layers, surface epithelium, tunica albuginea, and in superficial and deep stroma cells. No staining was noticed in apoptotic bodies of atretic follicles. Expression of PR in follicle cells indicates an intrafollicular role of progesterone. The higher expression in thecal cells compared with follicle cells indicates that thecal cells mediate some effects of progesterone on the follicular development. Superficial stroma cells showing high expression might have a similar influence on primordial and primary follicles. In general, luteal cells had a lower expression than follicle cells, which may be explained by the down-regulatory effect of locally produced progesterone. The lower expression in luteal cells during pregnancy can be due to the longer life span of this corpus luteum and concomitant degeneration of its PR. The high and rather constant expression of PR in cells of the surface epithelium remains to be elucidated.

Modeling and simulation of pathways in menopause

The analytical representation and simulation of complex molecular pathways can contribute to understanding and evaluating physiological as well as pathological processes. We are interested in modeling the processes of menopause to stratify women in terms of the genotypic and environmental components and their implications for development of individualized risk of postmenopausal disorders, e.g., breast and ovarian cancer, cardiovascular disease, and osteoporosis. We have initiated this study using the UltraSAN package to analyze the pathway associated with estrogen production. This model incorporates detailed information about the hormone factors affecting estrogen production, and the simulations carried out are based on published experimental data corresponding to hormone levels during the course of the normal female reproductive cycle. The agreement between the experimental data and the simulation is typically less than 2 ng/ml or 2 pg/ml respectively for progesterone and estradiol output. This approach further permits inclusion of information about an SNP observed in the gene coding for the enzyme aromatase as a model to study the impact of reduced enzymatic activity on hormone levels.