The road to ovulation: the role of oestrogens

Therapeutic prospect on umbilical cord mesenchymal stem cells in animal model with primary ovarian insufficiency: a meta-analysis

Background

Primary ovarian insufficiency (POI) leads to not only infertile but several adverse health events to women. Traditional treatment methods have their own set of limitations and drawbacks that vary in degree. Application of human umbilical cord mesenchymal stem cell (hUCMSC) is a promising strategy for POI. However, there is a lack of literatures on application of hUCMSC in human. Animal experimental model, however, can reflect the potential effectiveness of this employment. This study aimed to evaluate the curative effect of hUCMSC on animals with POI on a larger scale.

Methods

To gather data, Pubmed, Embase, and Cochrane Library were searched for studies published up to April 2022. Various indices, including the animals' estrous cycle, serum sex hormone levels, and follicle number in the ovary, were compared between the experimental group and those with Premature Ovarian Insufficiency (POI).

Results

The administration of human umbilical cord-derived mesenchymal stem cells (hUCMSC) has been shown to significantly improve the estrous cycle (RR: 3.32, 95% CI: [1.80, 6.12], I² = 0%, P = 0.0001), but robustly decrease its length (SMD: -1.97, 95% CI: [-2.58, -1.36], I² = 0%, P < 0.00001). It can also strikingly increase levels of serum estradiol (SMD: 5.34, 95% CI: [3.11, 7.57], I² = 93%, P < 0.00001) and anti-müllerian hormone (SMD: 1.92, 95% CI: [0.60, 3.25], I² = 68%, P = 0.004). Besides, it lowers levels of serum follicle-stimulating hormone (SMD: -3.02, 95% CI: [-4.88, -1.16], I² = 93%, P = 0.001) and luteinising hormone (SMD: -2.22, 95% CI: [-3.67, -0.76], I² = 78%, P = 0.003), and thus collectively promotes folliculogenesis (SMD: 4.90, 95% CI: [3.92, 5.88], I² = 0%, P < 0.00001).

Conclusions

Based on the presented findings, it is concluded that the administration of hUCMSC in animal models with POI can result in significant improvements in several key indicators, including estrous cycle recovery, hormone level modulation, and promotion of folliculogenesis. These positive outcomes suggest that hUCMSC may have potential as a treatment for POI in humans. However, further research is needed to establish the safety and efficacy of hUCMSC in humans before their clinical application.

Systematic review registration

https://inplasy.com/inplasy-2023-5-0075/, identifier: INPLASY202350075.

Fetal Estrogens are not Involved in Sex Determination But Critical for Early Ovarian Differentiation in Rabbits

AROMATASE is encoded by the CYP19A1 gene and is the cytochrome enzyme responsible for estrogen synthesis in vertebrates. In most mammals, a peak of CYP19A1 gene expression occurs in the fetal XX gonad when sexual differentiation is initiated. To elucidate the role of this peak, we produced 3 lines of TALEN genetically edited CYP19A1 knockout (KO) rabbits that were devoid of any estradiol production. All the KO XX rabbits developed as females with aberrantly small ovaries in adulthood, an almost empty reserve of primordial follicles, and very few large antrum follicles. Ovulation never occurred. Our histological, immunohistological, and transcriptomic analyses showed that the estradiol surge in the XX fetal rabbit gonad is not essential to its determination as an ovary, or for meiosis. However, it is mandatory for the high proliferation and differentiation of both somatic and germ cells, and consequently for establishment of the ovarian reserve.

Hyperin Alleviates Triptolide-Induced Ovarian Granulosa Cell Injury by Regulating AKT/TSC1/mTORC1 Signaling

Premature ovarian insufficiency (POI) is characterized by the loss of ovarian function before 40 years of age and affects approximately 1% of women worldwide. Caragana sinica is a traditional Miao (a Chinese ethnic minority) medicine that improves ovarian function and follicular development. In the present study, we aimed to investigate the effect of active ingredients of C. sinica on POI and determine underlying mechanisms. Herein, the chemical composition of the C. sinica compound was analyzed using ultra-high-performance liquid chromatography, which identified hyperin (HR) as one of the main ingredients in C. sinica. Then, interaction targets of HR and POI were predicted and analyzed using network pharmacology and bioinformatics. The effect of HR on triptolide (TP)-induced granulosa cell injury was evaluated, and the underlying mechanism was explored based on bioinformatic results. A total of 100 interaction targets for POI and HR were obtained. The protein-protein interaction network of identified interaction targets emphasized the topological importance of AKT1. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that HR might regulate POI by modulating the mechanistic target of rapamycin (mTOR) signaling pathway. In addition, the KEGG graph of the mTOR signaling pathway revealed that AKT phosphorylation inhibits the TSC1/2, while TSC1/2 activation inhibits the expression of mTORC1. The fundamental experiment revealed that HR increased proliferation, progesterone receptor levels, and estradiol levels decreased by TP in KGN cells. Additionally, HR alleviated TP-induced apoptosis and G1/G1 phase arrest in KGN cells. Western blotting demonstrated that HR increased the phosphorylation of AKT and mTORC1 and decreased TSC1 expression in TP-induced KGN cells. Collectively, our findings revealed that HR alleviates TP-induced granulosa cell injury by regulating AKT/TSC1/mTORC1 signaling, providing insight into the treatment of POI.

Treg deficiency-mediated TH 1 response causes human premature ovarian insufficiency through apoptosis and steroidogenesis dysfunction of granulosa cells

Immune dysregulation has long been proposed as a component of premature ovarian insufficiency (POI), but the underlying mediators and mechanisms remain largely unknown. Here we showed that patients with POI had augmented T helper 1 (TH 1) responses and regulatory T (Treg ) cell deficiency in both the periphery and the ovary compared to the control women. The increased ratio of TH 1:Treg cells was strongly correlated with the severity of POI. In mouse models of POI, the increased infiltration of TH 1 cells in the ovary resulted in follicle atresia and ovarian insufficiency, which could be prevented and reversed by Treg cells. Importantly, interferon (IFN) -γ and tumor necrosis factor (TNF) -α cooperatively promoted the apoptosis of granulosa cells and suppressed their steroidogenesis by modulating CTGF and CYP19A1. We have thus revealed a previously unrecognized Treg cell deficiency-mediated TH 1 response in the pathogenesis of POI, which should have implications for therapeutic interventions in patients with POI.

The influence of physiological status on the reproductive behaviour of humpback whales (Megaptera novaeangliae)

For most cetacean species, there is little known about how an individual's physiology influences its behaviour. Humpback whales (Megaptera novaeangliae) are a good candidate to examine such links as they have a well-described distribution and behaviour, can be consistently sampled using remote biopsy systems, and have been the subject of several previous endocrine studies. The objective here was to examine whether a female humpback whale's social state (i.e. escorted by a male or not) is related to her endocrine condition, and whether male dominance ranking is related to testosterone levels. Skin and blubber biopsies were collected from the east and west Australian humpback whale populations in 2010-2016 (n = 252) at multiple times throughout the winter-spring breeding season. Steroid hormones were extracted from blubber and concentrations of progesterone (a marker for pregnancy), testosterone (a marker of male testicular activity) and oestradiol (a potential marker of ovarian activity) measured using enzyme-immunoassays. Principal escorts-the dominant males in mixed sex groups-had significantly higher blubber testosterone levels (mean ± SE; 1.43 ± 0.20 ng/g wet weight) than subordinate, secondary escorts (0.69 ± 0.06 ng/g wet weight). Females that were escorted by males typically possessed elevated blubber oestradiol levels (1.96 ± 0.25 ng/g wet weight; p = 0.014); few were considered to be pregnant (p = 0.083). 'Unescorted' females displayed characteristically lower blubber oestradiol levels (0.56 ± 0.06 ng/g wet weight). Together, these results are consistent with 'challenge hypothesis' theory and suggest the existence of associated reproductive patterns in humpback whales.

Effect of Hyperin and Icariin on steroid hormone secretion in rat ovarian granulosa cells

AIM OF THE STUDY

This study was designed to investigate the effect of different concentrations of Hyperin and Icariin (ICA)on proliferation and the secretion of estrogen (E2), and progesterone (P) in granulosa cells, and to explore the effect of Hyperin and Icariin on the expression of CYP17 and CYP19.

MATERIALS AND METHODS

Rat ovary granulosa cells were cultured in vitro and treated with different concentrations of Hyperin and Icariin. The proliferation of ovarian granulosa cells was measured with the MTT assay. The concentration of estradiol was measured with a magnetic particle-based enzyme-linked immunosorbent assay (ELISA) kit. The CYP17 and CYP19 mRNA expression was detected by quantitative real-time reverse-transcription polymerase chain reaction (qRT-PCR). The CYP17 and CYP19 protein expression was determined with Western blotting.

RESULTS

Hyperin (50 μg/l) and Icariin (10 μg/l) significantly increased proliferation of ovarian granulosa cells and secretion of estrogen and progesterone. Hyperin and Icariin stimulated the mRNA and protein expression of CYP17 and CYP19.

CONCLUSIONS

These results showed that Hyperin and Icariin can promote the secretion of E2 and P through up-regulation of CYP17 and CYP19. Frequently used Chinese herbs like Cuscuta Chinensis Lam and Epimedium Brevicornu maxim, which contain Hyperin and Icariin, could improve the ovarian endocrine function through these effects.

Chitosan Hydrogel Supports Integrity of Ovarian Follicles during In Vitro Culture: A Preliminary of A Novel Biomaterial for Three Dimensional Culture of Ovarian Follicles

Objective

Testing novel biomaterials for the three dimensional (3D) culture of ovarian follicles may ultimately lead to a culture model which can support the integrity of follicles during in vitro culture (IVC). The present study reports the first application of a chitosan (CS) hydrogel in culturing mouse preantral follicles.

Materials and Methods

In this interventional experiment study, CS hydrogels with the concentrations of 0.5, 1, and 1.5% were first tested for fourier transform infrared spectroscopy (FT-IR), Compressive Strength, viscosity, degradation, swelling ratio, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cytotoxicity and live/dead assay. Thereafter, mouse ovarian follicles were encapsulated in optimum concentration of CS (1%) and compared with those in alginate hydrogel. The follicular morphology, quality of matured oocyte and steroid secretion in both CS and alginate were assessed by enzyme-linked immunosorbent assay (ELISA). The expression of folliculogenesis, endocrine, and apoptotic related genes was also evaluated by quantitative real-time polymerase chain reaction (qRT-PCR) and compared with day that in 0.

Results

The rates of survival, and diameter of the follicles, secretion of estradiol, normal appearance of meiotic spindle and chromosome alignment were all higher in CS group compared with those in alginate group (P≤0.05). The expression of Cyp19a1 and Lhcgr in CS group was significantly higher than that of the alginate group (P≤0.05).

Conclusion

The results showed that CS is a permissive hydrogel and has a beneficial effect on encapsulation of ovarian follicle and its further development during 3D culture.

Retinoic acid signaling in ovarian folliculogenesis and steroidogenesis

Retinoids are essential for reproduction. Most research has focused on the role of retinoic acid signaling in the regulation of meiosis during early fetal germ cell development. However, less attention has been paid to the possible effects of retinoic acid signaling in adult female gonads. Retinoic acid, its receptors, and the key enzymes required for retinoic acid synthesis are expressed in the ovaries and they are involved in the regulation of folliculogenesis and steroidogenesis. Exposure to compounds that can interfere with normal retinoic acid signaling is associated with adverse ovarian outcomes, including altered steroidogenesis and reduction in indicators of ovarian reserve in women and laboratory animal models. These observations call for more attention to retinoids as regulators of adult ovarian physiology and as possible targets of endocrine disruption by environmental chemicals. In this review, we summarize the current knowledge of retinoids in folliculogenesis and steroidogenesis in post-pubertal mammalian ovaries.

The Impact of Variants in Genes Associated with Estradiol Synthesis on Hormone Levels and Oocyte Retrieval in Patients Who Underwent Controlled Ovarian Hyperstimulation

AIMS

To correlate differences in estradiol levels in serum and follicular fluid with genetic variants and to determine if they play a role in the results following assisted reproductive technology (ART).

PATIENTS AND METHODS

A cross-sectional study was developed at the Ideia Fértil Institute of Reproductive Health. Two hundred two female patients were selected and underwent controlled ovarian hyperstimulation cycles. Patients for this study were chosen based on their male partners' infertility. Genotypes of selected variants of CYP19A1, CYP17A1, HSD17, and COMT were compared to the estradiol measurements from follicular fluid and serum, as well as to the number and maturation status of the oocytes retrieved.

RESULTS

Patients with the variant homozygous genotype AA of CYP19A1 (rs10046) showed increased serum concentrations of estradiol when compared to patients with other genotypes (p = 0.005). The same polymorphism effect was not observed in follicular fluid. This CYP19A1 variant did not affect the number of oocytes recovered nor their maturation level.

CONCLUSION

The CYP19A1 variant is associated with an estradiol imbalance in serum. Other pathways, however, may contribute to the formation of the final estradiol metabolite in follicular fluid as well as its impact on the oocyte maturation.

Responses of gonadal transcriptome and physiological analysis following exposure to 17α-ethynylestradiol in adult rare minnow Gobiocypris rarus

17α-ethynylestradiol (EE2), a synthetic estrogen commonly used in the oral contraceptive pills, disrupts the sexual differentiation, gonadal development and reproduction in aquatic species. Nowadays aquatic species and even humans still have the potential risks of exposure to EE2. However, the mechanism of EE2 endocrine disruption is still unclear. Aiming to elucidate molecular mechanisms, we analyzed transcriptome profiling of gonads, gonadal histology and the sex steroid hormones in response to EE2 in G. rarus. Through this study, we obtained eight RNA-Seq libraries upon EE2 exposure, and found some key genes and pathways in correlation with the disruption effects of EE2. We found EE2 could disrupt oocyte development and spermatogenesis in adult G. rarus, and EE2 has more obvious disruption effects on male G. rarus than females. Interestingly, EE2 was indicated to be an exogenous DPC-inducing agent and ppp2r3b was suggested to be a spermatogenesis candidate gene in rare minnow. The differential gene expressions of rps30, samp9, ppp2r3b and spartan upon EE2 exposure suggest EE2's disruption effects on gonads could attribute to altered pathways of translation, ribosome biogenesis and cell division.

Brain-derived neurotrophic factor promotes human granulosa-like tumor cell steroidogenesis and proliferation by activating the FSH receptor-mediated signaling pathway

Brain-derived neurotrophic factor (BDNF) and FSH receptor (FSHR) are expressed in ovarian granulosa cells, and play important roles in regulating follicle growth and oocyte maturation. Studies have linked the BDNF-associated signaling pathway to FSHR mRNA expression in the regulation of follicle development, but the mechanisms remain unknown. In the current study, we found that BDNF stimulated the secretion of estradiol and progesterone, and increased the proliferation of KGN cells (human granulosa-like tumor cell line). BDNF treatment also increased phosphorylated and ubiquitinated FSHR, and activated cAMP/PKA/CREB signaling pathway. Moreover, inhibition of BDNF expression by siRNA markedly reduced the estradiol secretion and down-regulated FSHR, aromatase and phosphorylated CREB; meanwhile, FSH treatment partly alleviated the effects of BDNF siRNA on KGN cells. These findings suggested that BDNF modulates graunlosa cell functions and the action probably mediated by FSHR-coupled signaling pathway, to affect aromatase-mediated steroidogenesis. These results provide an alternative target to optimize ovarian granulosa cell function.

Short-term hypertonic exposure enhances in vitro follicle growth and meiotic competence of enclosed oocytes while modestly affecting mRNA expression of aquaporin and steroidogenic genes in the domestic cat model

Using the domestic cat as a non-rodent, larger animal model, the objective was to determine the impact of a brief incubation in a hypertonic microenvironment on (1) ovarian follicle and oocyte growth in vitro, (2) developmental capacity of the resident oocyte, and (3) expression of aquaporin (AQP) genes in parallel with genes involved in regulation of folliculogenesis. In Study 1: Secondary or early antral follicles encapsulated in 0.5% alginate were allocated to one of three treatment groups: 1) culture in standard medium at 290 mOsm for 15 d (Control); 2) incubation in 350 mOsm medium for 1 h followed by culture in standard medium for 15 d (Hypertonic-1h); or 3) incubation in 350 mOsm medium for 24 h followed by incubation in standard medium for additional 14 d (Hypertonic-24h). After measuring follicle and oocyte diameters on Day 15, in vitro-grown oocytes were incubated for 24 h before assessing nuclear status. In Study 2: secondary or early antral follicles were subjected to one of the three treatments: 1) culture in standard medium at 290 mOsm for 48 h; 2) incubation in 350 mOsm medium for 1 h followed by culture in standard medium for additional 47 h; or 3) incubation in 350 mOsm medium for 24 h followed by culture in standard medium for additional 24 h. At the end of the culture period, all follicles were assessed for mRNA level of Cyp17a1, Cyp19a1, Star, Aqp1, 3, 5, 7 and 8 as well as Fshr using qPCR. Freshly collected follicles also were subjected to gene expression analysis and served as the 'Non-cultured control'. Hypertonic-24h follicles grew larger (P < 0.05) than the control, whereas those in Hypertonic-1h group exhibited intermediate growth, especially when the culture started at the early antral stage. Oocytes in the Hypertonic-24h group were larger and resumed meiosis at a higher rate than in the other treatments. In vitro culture affected (P < 0.05) mRNA expression of Cyp19a1, Star, Aqp1, and Aqp7 in both the secondary and early antral stage while Fshr was only affected in the former compared to the non-cultured control. Pre-incubating follicles in 350 mOsm medium for 24 h enhanced (P < 0.05) Star and Aqp7 while decreasing (P < 0.05) Aqp1 expression compared to the control in secondary follicles, but not in the early antral stage. In summary, short-term hypertonic exposure promoted cat follicle development in vitro (including the meiotic competence of the enclosed oocyte) possibly through a mechanism that does not involve water transport genes.

Effects of isoliquiritigenin on ovarian antral follicle growth and steroidogenesis

Isoliquiritigenin is a botanical estrogen used as a dietary supplement. Previous studies show that other botanical estrogens affect ovarian estradiol synthesis, but isoliquiritigenin's effects on the ovary are unknown. Thus, this study tested the hypothesis that isoliquiritigenin inhibits ovarian antral follicle growth and steroidogenesis. Antral follicles from CD-1 mice were cultured with vehicle control (dimethyl sulfoxide; DMSO) or isoliquiritigenin (0.6μM, 6 μM, 36 μM, and 100 μM) for 48-96h. During culture, follicle diameters were measured daily to assess follicle growth. After culture, media were collected for hormone assays and follicles were collected for gene expression analysis of steroidogenic enzymes. Isoliquiritigenin inhibited antral follicle growth and altered estradiol, testosterone, and progesterone levels. Additionally, isoliquiritigenin altered the mRNA levels of cytochrome P450 steroid 17-α-hydroxylase 1, aromatase, 17β-hydroxysteroid dehydrogenase 1, and steroidogenic acute regulatory protein. These data indicate that exposure to isoliquiritigenin inhibits growth and disrupts steroid production in antral follicles.

Age and gender effects on bone mass density variation: finite elements simulation

Bone remodeling is a physiological process by which bone constantly adapts its structure to changes in long-term loading manifested by interactions between osteoclasts and osteoblasts. This process can be influenced by many local factors, via effects on bone cells differentiation and proliferation, which are produced by bone cells and act in a paracrine or autocrine way. The aim of the current work is to provide mechanobiological finite elements modeling coupling both cellular activities and mechanical behavior in order to investigate age and gender effects on bone remodeling evolution. A series of computational simulations have been performed on a 2D and 3D human proximal femur. An age- and gender-related impacts on bulk density alteration of trabecular bone have been noticed, and the major actors responsible of this phenomenon have been then discussed.

Genistein exposure inhibits growth and alters steroidogenesis in adult mouse antral follicles

Genistein is a naturally occurring isoflavone phytoestrogen commonly found in plant products such as soybeans, lentils, and chickpeas. Genistein, like other phytoestrogens, has the potential to mimic, enhance, or impair the estradiol biosynthesis pathway, thereby potentially altering ovarian follicle growth. Previous studies have inconsistently indicated that genistein exposure may alter granulosa cell proliferation and hormone production, but no studies have examined the effects of genistein on intact antral follicles. Thus, this study was designed to test the hypothesis that genistein exposure inhibits follicle growth and steroidogenesis in intact antral follicles. To test this hypothesis, antral follicles isolated from CD-1 mice were cultured with vehicle (dimethyl sulfoxide; DMSO) or genistein (6.0 and 36μM) for 18-96h. Every 24h, follicle diameters were measured to assess growth. At the end of each culture period, the media were pooled to measure hormone levels, and the cultured follicles were collected to measure expression of cell cycle regulators and steroidogenic enzymes. The results indicate that genistein (36μM) inhibits growth of mouse antral follicles. Additionally, genistein (6.0 and 36μM) increases progesterone, testosterone, and dehydroepiandrosterone (DHEA) levels, but decreases estrone and estradiol levels. The results also indicate that genistein alters the expression of steroidogenic enzymes at 24, 72 and 96h, and the expression of cell cycle regulators at 18h. These data indicate that genistein exposure inhibits antral follicle growth by inhibiting the cell cycle, alters sex steroid hormone levels, and dysregulates steroidogenic enzymes in cultured mouse antral follicles.

Cross-Talk Between FSH and Endoplasmic Reticulum Stress: A Mutually Suppressive Relationship

Suboptimal cellular conditions result in the accumulation of unfolded proteins in the endoplasmic reticulum (ER) and trigger ER stress. In this study, we investigated the effects of follicle stimulating hormone (FSH) on ER stress in granulosa cells (GCs) obtained from 3-week-old female C57BL6 mice 24 or 48 hours after intraperitoneal injection of 5 IU pregnant mare's serum gonadotropin (PMSG), and in primary mouse GCs in culture treated with FSH (10-100 mIU/mL) for 24 or 48 hours. Moreover, mouse GCs in culture were treated with tunicamycin (Tm) or thapsigargin (Tp), which induce ER stress by inhibiting N-glycosylation of ER proteins and ER calcium adenosine triphosphatase, respectively, and their response to FSH was evaluated. We found that FSH attenuated ER stress in mouse GCs in vivo and in vitro; messenger RNA levels of ER stress-associated genes Xbp1s, Atf6, Chop, and Casp12 were decreased upon exposure to FSH/PMSG. Activating transcription factor 4 protein levels also demonstrated consistent decrease following FSH stimulation. Both Tm and Tp treatments inhibited FSH response, ER stress-induced cells did not show any change in estradiol levels in response to FSH, whereas in untreated GCs, estradiol production increased 3-fold after incubation with FSH for 60 hours. Furthermore, ER stress-induced cells failed to demonstrate aromatase (Cyp19a1) expression upon exposure to FSH. Importantly, under high-ER stress conditions FSH stimulation was unable to downregulate the expression of ER stress-associated genes. Our findings suggest that FSH decreases ER stress in GCs under physiologic conditions. However, under conditions that cause a significant increase in ER stress, FSH response is attenuated.

Effects of 17 α-methyltestosterone on transcriptome, gonadal histology and sex steroid hormones in rare minnow Gobiocypris rarus

The 17α-methyltestosterone (MT), a synthetic androgen, is known for its interference effects on the endocrine system. Aiming to investigate the transcriptome profiling of gonads induced by MT and to understand the molecular mechanism by which MT causes adverse effects in fish, transcriptome profiling of gonads, gonadal histology and the sex steroid hormones in response to MT were analyzed in Gobiocypris rarus. Eight libraries, 4 from the ovary and 4 from the testis, were constructed and sequenced and then a total number of clean reads per sample ranging from 7.03 to 9.99 million were obtained. In females, a total of 191 transcripts were differentially regulated by MT, consisting of 102 up-regulated transcripts and 89 down-regulated transcripts. In males, 268 differentially expressed genes with 108 up-regulated and 160 down-regulated were detected upon MT exposure. Testosterone serves as the major sex steroid hormone content in G. rarus of both sexes. The concentrations of 17β-estradiol, testosterone and 11-ketotestosterone were significantly increased in females and decreased in males after MT exposure. Interestingly, MT caused a decreased number of vitellogenic oocytes in the ovary and spermatozoa in the testis. After MT exposure, four differentially expressed genes (ndufa4, slc1a3a, caskin-2 and rpt3) were found in G. rarus of both sexes. Overall, we suggest that MT seemed to affect genes involved in pathways related to physiological processes in the gonads of G. rarus. These processes include the electron transfer of Complex IV, endothelial cell activation, axon growth and guidance, and proteasome assembly and glutamate transport metabolic.

Evaluation of follicular synchronization caused by estrogen administration and its reproductive outcome

To evaluate multiple follicular development synchronization after estrogen stimulation in prepubertal mice, follicular responsiveness to gonadotropin superovulation, the prospective reproductive potential and ovarian polycystic ovary syndrome (PCOS)-like symptoms at adulthood, prepubertal mice were intraperitoneally injected with estrogen to establish an animal model with solvent as control. When synchronized tertiary follicles in ovaries, in vitro oocyte maturation and fertilization rates, blastocyst formation rate, developmental potential into offspring by embryo transfer, adult fertility and PCOS-like symptoms, and involved molecular mechanisms were focused, it was found that estrogen stimulation (10 μg/gBW) leads to follicular development synchronization at the early tertiary stage in prepubertal mice; reproduction from oocytes to offspring could be realized by means of the artificial reproductive technology though the model mice lost their natural fertility when they were reared to adulthood; and typical symptoms of PCOS, except changes in inflammatory pathways, were not remained up to adulthood. So in conclusion, estrogen can lead to synchronization in follicular development in prepubertal mice, but does not affect reproductive outcome of oocytes, and no typical symptoms of PCOS remained at adulthood despite changes related to inflammation.

Mono(2-ethylhexyl) phthalate accelerates early folliculogenesis and inhibits steroidogenesis in cultured mouse whole ovaries and antral follicles

Humans are ubiquitously exposed to di(2-ethylhexyl) phthalate (DEHP), which is an environmental toxicant present in common consumer products. DEHP potentially targets the ovary through its metabolite mono(2-ethylhexyl) phthalate (MEHP). However, the direct effects of MEHP on ovarian folliculogenesis and steroidogenesis, two processes essential for reproductive and nonreproductive health, are unknown. The present study tested the hypotheses that MEHP directly accelerates early folliculogenesis via overactivation of phosphatidylinositol 3-kinase (PI3K) signaling, a pathway that regulates primordial follicle quiescence and activation, and inhibits the synthesis of steroid hormones by decreasing steroidogenic enzyme levels. Neonatal ovaries from CD-1 mice were cultured for 6 days with vehicle control, DEHP, or MEHP (0.2-20 μg/ml) to assess the direct effects on folliculogenesis and PI3K signaling. Further, antral follicles from adult CD-1 mice were cultured with vehicle control or MEHP (0.1-10 μg/ml) for 24-96 h to establish the temporal effects of MEHP on steroid hormones and steroidogenic enzymes. In the neonatal ovaries, MEHP, but not DEHP, decreased phosphatase and tensin homolog levels and increased phosphorylated protein kinase B levels, leading to a decrease in the percentage of germ cells and an increase in the percentage of primary follicles. In the antral follicles, MEHP decreased the mRNA levels of 17alpha-hydroxylase-17,20-desmolase, 17beta-hydroxysteroid dehydrogenase, and aromatase leading to a decrease in testosterone, estrone, and estradiol levels. Collectively, MEHP mediates the effect of DEHP on accelerated folliculogenesis via overactivating PI3K signaling and inhibits steroidogenesis by decreasing steroidogenic enzyme levels.

Di(2-ethylhexyl) phthalate inhibits antral follicle growth, induces atresia, and inhibits steroid hormone production in cultured mouse antral follicles

Di(2-ethylhexyl) phthalate (DEHP) is a ubiquitous environmental toxicant found in consumer products that causes ovarian toxicity. Antral follicles are the functional ovarian units and must undergo growth, survival from atresia, and proper regulation of steroidogenesis to ovulate and produce hormones. Previous studies have determined that DEHP inhibits antral follicle growth and decreases estradiol levels in vitro; however, the mechanism by which DEHP elicits these effects is unknown. The present study tested the hypothesis that DEHP directly alters regulators of the cell cycle, apoptosis, and steroidogenesis to inhibit antral follicle functionality. Antral follicles from adult CD-1 mice were cultured with vehicle control or DEHP (1-100 μg/ml) for 24-96 h to establish the temporal effects of DEHP on the follicle. Following 24-96 h of culture, antral follicles were subjected to gene expression analysis, and media were subjected to measurements of hormone levels. DEHP increased the mRNA levels of cyclin D2, cyclin dependent kinase 4, cyclin E1, cyclin A2, and cyclin B1 and decreased the levels of cyclin-dependent kinase inhibitor 1A prior to growth inhibition. Additionally, DEHP increased the mRNA levels of BCL2-associated agonist of cell death, BCL2-associated X protein, BCL2-related ovarian killer protein, B-cell leukemia/lymphoma 2, and Bcl2-like 10, leading to an increase in atresia. Further, DEHP decreased the levels of progesterone, androstenedione, and testosterone prior to the decrease in estradiol levels, with decreased mRNA levels of side-chain cleavage, 17α-hydroxylase-17,20-desmolase, 17β-hydroxysteroid dehydrogenase, and aromatase. Collectively, DEHP directly alters antral follicle functionality by inhibiting growth, inducing atresia, and inhibiting steroidogenesis.

Asymmetric steroidogenic response by the ovaries to the vasoactive intestinal peptide

In vitro the vasoactive intestinal peptide (VIP) stimulates progesterone, androgens, and estradiol secretion, and the effects are time-dependent. The present study analyzed the acute (1 h) and sub-acute (24 h) effects of unilateral injection of VIP into the ovarian bursa on each day of the estrous cycle on progesterone, testosterone, and estradiol serum levels. Cyclic 60-day-old virgin female rats on diestrus-1, diestrus-2, proestrus, or estrus were injected with saline or VIP 10(-6) M into the left or right ovarian bursa. One hour after saline injection on each day of estrus cycle, progesterone levels were higher than in control animals. The acute effects of saline solution on testosterone and estradiol levels were asymmetric and varied during the estrous cycle. In comparison with saline groups, the effects of VIPergic stimulation on progesterone, testosterone, and estradiol serum levels depend on the time elapsed between treatment and autopsy and vary during the estrous cycle. An acute asymmetric response from the ovaries to the VIP was observed at diestrus-1, diestrus-2, and proestrus on progesterone and estradiol levels. The asymmetries on testosterone levels were observed at diestrus-1, diestrus-2, and estrus days. The present results suggest that in the cyclic rat, each ovary has different sensitivities to VIPergic stimulation which depends on the endocrine status of the animal.

The effects of phthalates on the ovary

Phthalates are commonly used as plasticizers in the manufacturing of flexible polyvinyl chloride products. Large production volumes of phthalates and their widespread use in common consumer, medical, building, and personal care products lead to ubiquitous human exposure via oral ingestion, inhalation, and dermal contact. Recently, several phthalates have been classified as reproductive toxicants and endocrine-disrupting chemicals based on their ability to interfere with normal reproductive function and hormone signaling. Therefore, exposure to phthalates represents a public health concern. Currently, the effects of phthalates on male reproduction are better understood than the effects on female reproduction. This is of concern because women are often exposed to higher levels of phthalates than men through their extensive use of personal care and cosmetic products. In the female, a primary regulator of reproductive and endocrine function is the ovary. Specifically, the ovary is responsible for folliculogenesis, the proper maturation of gametes for fertilization, and steroidogenesis, and the synthesis of necessary sex steroid hormones. Any defect in the regulation of these processes can cause complications for reproductive and non-reproductive health. For instance, phthalate-induced defects in folliculogenesis and steroidogenesis can cause infertility, premature ovarian failure, and non-reproductive disorders. Presently, there is a paucity of knowledge on the effects of phthalates on normal ovarian function; however, recent work has established the ovary as a target of phthalate toxicity. This review summarizes what is currently known about the effects of phthalates on the ovary and the mechanisms by which phthalates exert ovarian toxicity, with a particular focus on the effects on folliculogenesis and steroidogenesis. Further, this review outlines future directions, including the necessity of examining the effects of phthalates at doses that mimic human exposure.

The ameliorative effect of propolis against methoxychlor induced ovarian toxicity in rat

A study was designed to evaluate ameliorative effect of propolis against methoxychlor (MXC) induced ovarian toxicity in rat. The organochlorine pesticide (MXC) is a known endocrine disruptor with estrogenic, anti-estrogenic, and anti-androgenic properties. To investigate whether chronic exposure to MXC could cause ovarian dysfunction, two groups of Sprague-Dawley adult female rats were exposed to MXC alone in a dose of 200mg/kg, twice/weekly, orally or MXC dose as previous plus propolis in a dose of 200mg/l/day, in drinking water for 10 months. Another two groups of rat were given corn oil (control) or propolis. Multiple reproductive parameters, ovarian weight, serum hormone levels, ovarian oxidative status and ovarian morphology were examined. In MXC-exposed group, there is a significant decrease in body and ovarian weight vs. control. MXC decreases serum estradiol and progesterone levels. A significant increase in the levels of lipid peroxidation was obtained while a significant decrease of the total antioxidant was recorded. Ovarian histopathology showed primary, secondary and vesicular follicles displaying an atretic morphology. Increase in the ovarian surface epithelium height accompanied with vacuolated, pyknotic oocytes were obtained. The previous toxic effects were neutralized by the administration of propolis in MXC+propolis group. The present results suggest that propolis may be effective in decreasing of MXC-induced ovarian toxicity in rat.

Effects of systemic administration or intrabursal injection of serotonin on puberty, first ovulation and follicular development in rats

To elucidate the role of serotonin in the onset of puberty, the effects of both systemic and in-ovarian bursa administration of serotonin on the neuroendocrine mechanism that modulates the onset of puberty, follicular development and first ovulation were evaluated. Two experiments were carried out. For the first, 25 or 37.5 mg kg–1 of bodyweight of serotonin creatinine sulfate was administered by a subcutaneous route to 30-day-old female rats. In the second experiment, serotonin creatinine sulfate was administered directly into the ovarian bursa of 34-day-old female rats. Systemic administration of 25 or 37.5 mg kg–1 of serotonin creatinine sulfate induced a delay in the ages of vaginal opening and first vaginal oestrus, a decrease in the number of ovulating animals, and serum concentrations of FSH, LH, oestradiol and progesterone. An increase in the number of Class 3 (>500 μm) and atretic follicles was observed in the ovaries of these animals. The administration of serotonin creatinine sulfate in the ovarian bursa did not modify the onset of puberty and ovulation, but a reduced serum concentration of oestradiol was observed. Our results suggest that serotonin acts on the components of the hypothalamus–hypophysis–ovary axis by modulating follicular development, ovarian functions and the onset of puberty.

Steroidogenic factor-1 is required for TGF-beta3-mediated 17beta-estradiol synthesis in mouse ovarian granulosa cells

The TGF-β superfamily members are indicated to play key roles in ovarian follicular development, such as granulosa cell proliferation, estrogens, and progesterone production. However, little is known about the roles of TGF-β3 in follicular development. In this study, we found that TGF-β3 was predominantly expressed in granulosa cells of mouse ovarian follicles, and it significantly promoted 17β-estradiol (E(2)) release in a dose-dependent manner. The orphan nuclear receptor steroidogenic factor-1 (SF-1) was required in TGF-β3-induced Cyp19a1 (a key rate-limiting enzyme for estrogen biosynthesis) expression and E(2) release. Additionally, TGF-β3 enhanced the binding of SF-1 to endogenous ovary-specific Cyp19a1 type II promoter, as evidenced by chromatin immunoprecipitation assays. The enhanced effect of SF-1 by TGF-β3 may be mediated through functional interactions between SF-1 and mothers against decapentaplegic homolog (Smad)3 (a mediator of TGF-β signaling pathway), because disruption of the interaction abolished the synergistic effects of SF-1, Smad3, and TGF-β3 on Cyp19a1 mRNA expression. RNA interference and chromatin immunoprecipitation studies also demonstrated that Smad3 was required for SF-1 binding to Cyp19a1 type II promoter and activation of Cyp19a1. Smad3 thus acts as a point of convergence that involves integration of SF-1 and TGF-β signaling in affecting E(2) production. Taken together, our data provide mechanistic insights into the roles of SF-1 in TGF-β3-mediated E(2) synthesis. Understanding of potential cross-points between extracellular signals affecting estrogen production will help to discover new therapeutic targets in estrogen-related diseases.

Methoxychlor reduces estradiol levels by altering steroidogenesis and metabolism in mouse antral follicles in vitro

The organochlorine pesticide methoxychlor (MXC) is a known endocrine disruptor that affects adult rodent females by causing reduced fertility, persistent estrus, and ovarian atrophy. Since MXC is also known to target antral follicles, the major producer of sex steroids in the ovary, the present study was designed to test the hypothesis that MXC decreases estradiol (E₂) levels by altering steroidogenic and metabolic enzymes in the antral follicles. To test this hypothesis, antral follicles were isolated from CD-1 mouse ovaries and cultured with either dimethylsulfoxide (DMSO) or MXC. Follicle growth was measured every 24 h for 96 h. In addition, sex steroid hormone levels were measured using enzyme-linked immunosorbent assays (ELISA) and mRNA expression levels of steroidogenic enzymes as well as the E₂ metabolic enzyme Cyp1b1 were measured using qPCR. The results indicate that MXC decreased E₂, testosterone, androstenedione, and progesterone (P₄) levels compared to DMSO. In addition, MXC decreased expression of aromatase (Cyp19a1), 17β-hydroxysteroid dehydrogenase 1 (Hsd17b1), 17α-hydroxylase/17,20-lyase (Cyp17a1), 3β hydroxysteroid dehydrogenase 1 (Hsd3b1), cholesterol side-chain cleavage (Cyp11a1), steroid acute regulatory protein (Star), and increased expression of Cyp1b1 enzyme levels. Thus, these data suggest that MXC decreases steroidogenic enzyme levels, increases metabolic enzyme expression and this in turn leads to decreased sex steroid hormone levels.

Effect of the methoxychlor metabolite HPTE on the rat ovarian granulosa cell transcriptome in vitro

Ovarian granulosa cells play a central role in steroidogenesis, which is critical for female reproduction. Follicle-stimulating hormone (FSH) promotes cyclic adenosine monophosphate (cAMP)-mediated signaling to regulate granulosa cell steroidogenesis. We have shown previously that 2,2-bis-(p-hydroxyphenyl)-1,1,1-trichloroethane (HPTE) inhibits FSH- and dibutyryl cAMP-stimulated steroidogenesis and affects the messenger RNA levels of steroidogenic pathway enzymes in rat granulosa cells. However, HPTE showed a differential effect in FSH- and cAMP-stimulated cells in that HPTE more completely blocked FSH- when compared to cAMP-driven steroidogenesis. The objective of this study was to analyze the effects of HPTE on global gene expression profiles in untreated granulosa cells and those challenged with FSH or cAMP. Granulosa cells from immature rats were cultured with 0, 1, 5, or 10 microM HPTE in the presence or absence of either 3 ng FSH/ml or 1mM cAMP for 48 h. Total RNA was isolated for real-time quantitative PCR and microarray analysis using the GeneChip Rat Genome 230 2.0 and ArrayAssist Microarray Suite. An investigation of changes in gene expression across all HPTE treatments showed that HPTE altered more genes in FSH- (approximately 670 genes) than in cAMP-stimulated cells (approximately 366 genes). Analysis confirmed that HPTE more effectively inhibited FSH- than cAMP-induced steroid pathway gene expression and steroidogenesis. Furthermore, expression patterns of novel genes regulating signal transduction, transport, cell cycle, adhesion, differentiation, motility and growth, apoptosis, development, and metabolism were all altered by HPTE. This study further established that HPTE exerts differential effects within the granulosa cell steroidogenic pathway and revealed that these effects include broader changes in gene expression.

The role of the aryl hydrocarbon receptor in the female reproductive system

In recent years, many studies have emphasized how changes in aryl hydrocarbon receptor (AHR)-mediated gene expression result in biological effects, raising interest in this receptor as a regulator of normal biological function. This review focuses on what is known about the role of the AHR in the female reproductive system, which includes the ovaries, Fallopian tubes or oviduct, uterus and vagina. This review also focuses on the role of the AHR in reproductive outcomes such as cyclicity, senescence, and fertility. Specifically, studies using potent AHR ligands, as well as transgenic mice lacking the AHR-signaling pathway are discussed from a viewpoint of understanding the endogenous role of this ligand-activated transcription factor in the female reproductive lifespan. Based on findings highlighted in this paper, it is proposed that the AHR has a role in physiological functions including ovarian function, establishment of an optimum environment for fertilization, nourishing the embryo and maintaining pregnancy, as well as in regulating reproductive lifespan and fertility. The mechanisms by which the AHR regulates female reproduction are poorly understood, but it is anticipated that new models and the ability to generate specific gene deletions will provide powerful experimental tools for better understanding how alterations in AHR pathways result in functional changes in the female reproductive system.

The mouse follicle microenvironment regulates antrum formation and steroid production: alterations in gene expression profiles

Folliculogenesis is a coordinated process, and the genes that regulate development are difficult to investigate in vivo. In vitro culture systems permit the assessment of individual follicles during development, thereby enabling gene expression patterns to be monitored during follicle development. Mouse multilayered secondary follicles (150-180 microm in diameter) were cultured in three-dimensional matrices of varying physical properties for up to 8 days. During this period of follicle growth in vitro, antrum formation and steroid production were monitored, and mRNA was isolated. The expression levels of genes (Star, Cyp11a1, Cyp17a1, Hsd3b1, Cyp19a1, Fshr, Lhcgr, Aqp7, Aqp8, Aqp9, and Hif1a) were measured and correlated to follicle developmental status. Follicles that developed an antrum and produced appropriate levels of estrogen and progesterone had unchanging expression of Star, Aqp7, Aqp8, and Hif1a and a 34-fold increase in Cyp19a1 expression at Day 8 of culture and had elevated Lhcgr at Days 6 and 8 of culture. Follicles that were healthy but did not form an antrum or produce appropriate levels of steroids, however, demonstrated increasing levels of Star, Aqp7, Aqp8, and Hif1a and a 15-fold increase in Cyp19a1 at Day 8 of culture, and Lhcgr levels were not elevated until Day 8 of culture. To our knowledge, this study provides the first temporal analysis of gene expression using individual culture in alginate hydrogels that correlates growth and steroidogenesis during follicle development and identifies expression patterns in healthy follicles and in developmentally disadvantaged follicles.

Biological functions and clinical implications of oestrogen receptors alfa and beta in epithelial tissues

For the past 10 years it is known that oestrogen functions through the activation of two oestrogen receptors (ERalpha and ERbeta). To the great surprise of endocrinologists, ERbeta was found to be widely distributed in tissues throughout the body including tissues previously considered as 'oestrogen insensitive'. The epithelium of the ventral prostate and lung as well as ovarian granulosa cells are ERalpha-negative but ERbeta-positive and in these tissues ERbeta seems to be involved in important physiological processes, like differentiation, extracellular matrix organization and stromal-epithelial communication. In tissues where both ERs are expressed, the two receptors seem to counteract each other. In the uterus, mammary gland and immune system, ERalpha promotes proliferation whereas ERbeta has pro-apoptotic and pro-differentiating functions. The challenge of the future will be to develop specific agonists, which can selectively activate/inactivate either ERalpha or ERbeta. These pharmaceuticals are likely to be of clinical importance in the prevention or treatment of various diseases.

A novel method for assessing sex-specific and genotype-specific response to injury in astrocyte culture

Female astrocytes sustain less cell death from oxygen-glucose deprivation (OGD) than male astrocytes. Arimidex, an aromatase inhibitor, abolishes these sex differences. To verify sex-dependent differences in P450 aromatase function in astrocyte cell death following OGD, we developed a novel method that uses sex-specific and genotype-specific single pup primary astrocyte cultures from wild-type (WT) and aromatase-knockout (ArKO) mice. After determining sex by external and internal examination as well as PCR and genotype by PCR amplification of tail cDNA, we established cultures from 1-3-day-old male and female WT and ArKO mice pups and grew them to confluence in estrogen-free media. Cell death was measured by lactate dehydrogenase (LDH) assay. Our study shows that, while WT female astrocytes are more resistant to OGD than WT male cells, sex differences disappear in ArKO cells. Cell death is significantly increased in ArKO compared to WT in female astrocytes but not male cells. Therefore, P450 aromatase appears to be essential in endogenous neuroprotection in females, and this finding may have clinical implications. This innovative technique may also be applied to other in vitro studies of sex-related functional differences.

Ovarian wedge resection restores fertility in estrogen receptor beta knockout (ERbeta-/-) mice

Ovulation rarely occurs in mice in which the estrogen receptor beta (ERbeta) gene has been inactivated (ERbeta-/- mice). Here, we investigated whether this subfertility is due to a defect in the ovary itself or to more general endocrine changes in ERbeta-/- mice. We transplanted ERbeta-/- ovaries into WT mice and WT ovaries into ERbeta-/- mice. Upon mating with ERbeta-/- males, fertility increased from 20% in control intact ERbeta-/- group to 40% in the WT recipients with ERbeta-/- ovaries. The transplantation procedure was not efficient, and when WT ovaries were transplanted into WT mice, fertility was only 36%. Surgical ovarian wedge resection, a procedure which induces ovulation in anovulatory women with polycystic ovarian syndrome, resulted in 100% fertility of ERbeta-/- mice. In ERbeta-/- mice, as the follicles enlarged, the thecal layer remained very compact (revealed by H&E and collagen staining), and there was no increase in vascularization (measured as smooth muscle actin). In addition, there was an increase in PDGF receptor alpha (PDGFRalpha) and a decrease in PDGFbeta expression in the granulosa cells, similar to what has been found in follitropin receptor knockout mice. After wedge resection, expression of both smooth muscle actin and PDGFRs was normalized. During normal follicular development, increased vascularization of the thecal layer is a prerequisite for further follicular growth. We suggest that the defect in ERbeta-/- mouse ovaries is a failure of communication between the granulosa and thecal layers. The follicles do not mature because of insufficient blood supply. This problem is overcome by stimulating neovascularization by simple wedge resection of the ovaries.

Follicle-stimulating hormone/cAMP regulation of aromatase gene expression requires beta-catenin

Estrogens profoundly influence the physiology and pathology of reproductive and other tissues. Consequently, emphasis has been placed on delineating the mechanisms underlying regulation of estrogen levels. Circulating levels of estradiol in women are controlled by follicle-stimulating hormone (FSH), which regulates transcription of the aromatase gene (CYP19A1) in ovarian granulosa cells. Previous studies have focused on two downstream effectors of the FSH signal, cAMP and the orphan nuclear receptor steroidogenic factor-1 (NR5A1). In this report, we present evidence for beta-catenin (CTNNB1) as an essential transcriptional regulator of CYP19A1. FSH induction of select steroidogenic enzyme mRNAs, including Cyp19a1, is enhanced by beta-catenin. Additionally, beta-catenin is present in transcription complexes assembled on the endogenous gonad-specific CYP19A1 promoter, as evidenced by chromatin immunoprecipitation assays. Transient expression and RNAi studies demonstrate that FSH- and cAMP-dependent regulation of this promoter is sensitive to alterations in the level of beta-catenin. The stimulatory effect of beta-catenin is mediated through functional interactions with steroidogenic factor-1 that involve four acidic residues within its ligand-binding domain, mutation of which attenuates FSH/cAMP-induced Cyp19a1 mRNA accumulation. Together, these data demonstrate that beta-catenin is essential for FSH/cAMP-regulated gene expression in the ovary, identifying a central and previously unappreciated role for beta-catenin in estrogen biosynthesis, and a potential broader role in other aspects of follicular maturation.

Methoxychlor induces atresia of antral follicles in ERalpha-overexpressing mice

Methoxychlor (MXC) is a pesticide that is known to bind to estrogen receptor alpha (ERalpha) and to induce atresia of antral ovarian follicles. Although studies have shown that MXC is toxic to the ovary, we hypothesize that perturbation to the estrogen-signaling system (i.e., increase or decrease in estrogen sensitivity) might alter ovarian responsiveness to MXC. Thus, we examined whether ERalpha overexpression alters the ability of MXC to increase follicle atresia. To do so, we employed a transgenic mouse model in which ERalpha can be inducibly overexpressed in animal tissues (ERalpha overexpressors). We dosed female controls and ERalpha overexpressors with sesame oil (vehicle control) or MXC (32 and 64 mg/kg/day) for 20 days. After dosing, the ovaries were collected for histological evaluation of follicle numbers and follicle atresia, while blood was collected for measurements of hormones. Estrous cycles were determined in all animals to ensure that all were terminated during estrus. Although there were no significant effects of MXC on the numbers of primordial, primary, and preantral follicles in both controls and ERalpha overexpressors, there was an effect on antral follicles. Specifically, our data indicate that 32 and 64 mg/kg MXC increased the percentage of atretic follicles compared to vehicle in both control and ERalpha overexpressor groups. Moreover, there was a clear trend toward greater sensitivity to 64 mg/kg MXC in ERalpha-overexpressing mice compared to control animals. Specifically, at the 64-mg/kg MXC dose, ERalpha-overexpressing mice had a significantly higher percentage of atretic follicles compared to control animals (controls = 21.5 +/- 3%, n = 5; ERalpha overexpressors = 37 +/- 23%, n = 9, p < or = 0.05 vs. controls). After 20 days of dosing, there were no differences in estradiol levels between controls and ERalpha-overexpressing mice in all treatment groups. Follicle-stimulating hormone (FSH) levels were similar in sesame oil-treated control mice and control mice treated with 32 mg/kg MXC, while control mice treated with 64 mg/kg MXC had significantly lower levels of FSH compared to sesame oil-treated controls (sesame oil = 4.31 +/- 0.7, MXC [64 mg/kg/day] = 1.89 +/- 0.4, n = 3, p < or = 0.02 vs. sesame oil). ERalpha-overexpressing mice treated with sesame oil, 32 or 64 mg/kg MXC, had similar FSH levels. Thus, we observed an increased percentage of atretic antral follicles in ERalpha-overexpressing mice treated with MXC compared to control mice treated with the same compound, suggesting that the ERalpha-signaling pathway plays an important role in MXC-induced atresia. The trend toward greater sensitivity to MXC in ERalpha-overexpressing mice compared to control animals cannot be explained by alterations in estradiol and/or FSH levels.

Steroid hormone synthesis in pregnancy

The goal of this article is to summarize what is known about the pathways of steroid hormone synthesis and metabolism in human pregnancy. Emphasis is placed on the distinctions between steroidogenic pathways in adults and those that are operative during human pregnancy.

Nonhuman primates contribute unique understanding to anovulatory infertility in women

Anovulatory infertility affects a large proportion of reproductive-aged women. Major improvements in successful clinical treatment of this prevalent disorder in women's health have been made possible because of biomedical research employing nonhuman primates. Experiments on female rhesus monkeys were the first to demonstrate that the key hypothalamic neurotransmitter, gonadotropin-releasing hormone, involved in stimulating pituitary gonadotropin synthesis, storage, and release was bioactive only when released in approximately hourly bursts. This breakthrough in understanding gonadotropin regulation enabled identification of hypogonadotropic, apparently normogonadotropic, and hypergonadotropic forms of anovulatory infertility, and development of appropriate stimulatory or inhibitory gonadotropin therapies. Treatments to overcome anovulatory infertility represent one of the major advances in clinical reproductive endocrinology during the last 25 yr. The future promise of nonhuman primate models for human ovulatory dysfunction, however, may be based on an increased understanding of molecular and physiological mechanisms responsible for fetal programming of adult metabolic and reproductive defects and for obesity-related, hyperinsulinemic impairment of oocyte development.

Prolongation of the follicular phase in in vitro fertilization results in a lower ongoing pregnancy rate in cycles stimulated with recombinant follicle-stimulating hormone and gonadotropin-releasing hormone antagonists

OBJECTIVE

To assess the effect of altering the timing of hCG administration on ongoing pregnancy rates in patients stimulated with recombinant FSH (rec-FSH) and GnRH antagonists for IVF.

DESIGN

Prospective, randomized, controlled trial.

SETTING

Tertiary referral center.

PATIENT(S)

Four hundred thirteen patients undergoing IVF.

INTERVENTION(S)

Rec-FSH stimulation starting on day 2 of the cycle combined with daily GnRH antagonist starting on day 6 of stimulation. Patients were randomized to receive 10000 IU of hCG either as soon as at least three follicles were >or=17 mm on ultrasound (early-hCG group, 208 patients) or 2 days later after this criterion was met (late-hCG group, 205 patients).

MAIN OUTCOME MEASURE(S)

Ongoing pregnancy rate.

RESULT(S)

Fertilization rates and number and quality of embryos transferred did not differ between the two groups. However, a significantly lower ongoing pregnancy rate was present in the late-hCG as compared with the early-hCG group (25.0% vs. 35.6%, respectively).

CONCLUSION(S)

Prolongation of the follicular phase in patients stimulated with rec-FSH and GnRH antagonists for IVF does not affect oocyte or embryo quality but is associated with a significantly lower ongoing pregnancy rate.

Expressional regulation of neuronal and cancer-related genes by estrogen in adult female rats

Adult female rats were ovariectomized and treated with or without estrogen for two weeks. mRNA was obtained from the hypothalamus, uterus, liver, kidney and skeletal muscle and analyzed by Northern blotting and/or RT-PCR. We examined two types of estrogen-responsive genes from rats, neuronal system-related genes (Amphiregulin, AR; Neuropeptide Y-Y1 receptor, NPY-Y1R; Bassoon, BSN; N-Cadherin, N-CADH) and estrogen-susceptible cancer-related genes (C-terminal binding protein interacting protein, CtIP), based on the results of a cDNA microarray analysis which was carried out to profile estrogen-responsive genes in the human breast cancer cell line MCF-7. The N-CADH gene showed identical response to that in MCF-7 cells. In the hypothalamus, all except the AR gene were down-regulated in their expression. In other tissues, the expression showed marked differences: expression of the BSN gene was not detected by either method, and the NPY-Y1R gene showed down-regulation in most tissues except for skeletal muscle. We then analyzed the time course of the estrogen-responsiveness of these genes in several tissues, finding changes in expression patterns especially in skeletal muscle but not in the hypothalamus. Our results show that the estrogen-responsive genes, which were demonstrated simply as either up- or down-regulated in their expression by estrogen in a human cell line using cDNA microarrays, exhibit tissue and temporal-specific expression patterns in adult female rats.

Initiation of gonadotropin-releasing hormone antagonist on day 1 as compared to day 6 of stimulation: effect on hormonal levels and follicular development in in vitro fertilization cycles

The objective of the present study was to assess the effect of altering the timing of GnRH antagonist initiation on the hormonal environment and follicular development in in vitro fertilization cycles. Sixty women undergoing in vitro fertilization participated in a prospective randomized controlled trial. Patients were stimulated with a fixed dose of 200 IU recombinant FSH, starting on d 2 of the cycle, and with GnRH-antagonist, starting either on d 1 (n = 30) or on d 6 of stimulation (n = 30). A significantly lower exposure to LH (P < 0.001) and estradiol (P < 0.001) during the follicular phase was observed in the d-1 group, compared with the d-6 group of antagonist administration. No differences in follicular development were seen between the two groups on either d 6 of stimulation or on the day of human chorionic gonadotropin administration. Similar fertilization rates, implantation rates, and ongoing pregnancy rates per transfer were, in addition, present between the two groups compared. In conclusion, administration of GnRH antagonist on d 1 (compared with d 6) of stimulation is associated with a lower exposure to LH and estradiol, which does not seem to affect follicular development.

Determination of steroidogenic potential of ovarian cells of the brushtail possum (Trichosurus vulpecula)

The ovary of the brushtail possum (Trichosurus vulpecula) secretes steroids; however, little is known about the identity of the steroidogenic cells in the ovary. The aim of the present study was to determine the identity of the ovarian cell types expressing mRNAs encoding proteins important for steroidogenesis and determine at what stage of follicular development they are expressed. The genes examined were those for steroidogenic factor-1 (SF-1), steroidogenic acute regulatory protein (StAR), cytochrome p450 side chain cleavage (P450scc), 3beta-hydroxysteroid dehydrogenase/Delta5,Delta4 isomerase (3betaHSD), cytochrome p45017alphahydroxylase (p45017alphaOH), and p450 aromatase (p450arom). None of the genes examined were expressed in oocytes at any stage of follicular development. SF-1 was expressed in granulosa cells from the type 2 or the primary stage of development and thereafter to the preovulatory stage. In addition, the theca interna of small and medium-size antral but not preovulatory follicles and the interstitial glands and corpora lutea expressed SF-1 mRNA. Granulosa cells of preantral and small to medium-size antral follicles were not capable of synthesizing steroids from cholesterol because they did not contain p450scc mRNA. However, granulosa cells of many of the small to medium-size antral follicles expressed p450arom and 3betaHSD mRNA. The interstitial glands, theca interna, and corpus luteum expressed StAR, p450scc, 3betaHSD, and p45017alphaOH mRNA, suggesting that these tissues are capable of synthesizing progestins and androgens. The corpus luteum expressed p450arom, indicating that this tissue also has the potential to secrete estrogens in this species.