Distinct Regulation by Steroids of Messenger RNAs for FSHR and CYP19A1 in Bovine Granulosa Cells

Enhancing differentiation of menstrual blood-derived stem cells into female germ cells using a bilayer amniotic membrane and nano-fibrous fibroin scaffold

Three-dimensional nanofiber scaffolds offer a promising method for simulating in vivo conditions within the laboratory. This study aims to investigate the influence of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold on the differentiation of human menstrual blood mesenchymal stromal/stem cells (MenSCs) into female germ cells. MenSCs were isolated and assigned to four culture groups: (i) MenSCs co-cultured with granulosa cells (GCs) using the scaffold (3D-T group), (ii) MenSCs using the scaffold alone (3D-C group), (iii) MenSCs co-cultured only with GCs (2D-T group), and (iv) MenSCs without co-culture or scaffold (2D-C group). Both MenSCs and GCs were independently cultured for two weeks before co-culturing was initiated. Flow cytometry was employed to characterize MenSCs based on positive markers (CD73, CD90, and CD105) and negative markers (CD45 and CD133). Additionally, flow cytometry and immunocytochemistry were used to characterize the GCs. Differentiated MenSCs were analyzed using real-time PCR and immunostaining. The real-time PCR results demonstrated significantly higher levels of VASA expression in the 3D-T group compared to the 3D-C, 2D-T, and 2D-C groups. Similarly, the SCP3 mRNA level in the 3D-T group was notably elevated compared to the 3D-C, 2D-T, and 2D-C groups. Moreover, the expression of GDF9 was significantly higher in the 3D-T group when compared to the 3D-C, 2D-T, and 2D-C groups. Immunostaining results revealed a lack of signal for VASA, SCP3, or GDF9 markers in the 2D-T group, while some cells in the 3D-T group exhibited positive staining for all these proteins. These findings suggest that the combination of a bilayer amniochorionic membrane/nanofibrous fibroin scaffold with co-culturing GCs facilitates the differentiation of MenSCs into female germ cells.

Dysfunction of Human Estrogen Signaling as a Novel Molecular Signature of Polycystic Ovary Syndrome

Estradiol (E2) is a major hormone-controlling folliculogenesis whose dysfunction may participate in polycystic ovary syndrome (PCOS) infertility. To determine whether both the concentration and action of E2 could be impaired in non-hyperandrogenic overweight PCOS women, we isolated granulosa cells (GCs) and follicular fluid (FF) from follicles of women undergoing ovarian stimulation (27 with PCOS, and 54 without PCOS). An analysis of the transcript abundance of 16 genes in GCs showed that androgen and progesterone receptor expressions were significantly increased in GCs of PCOS (by 2.7-fold and 1.5-fold, respectively), while those of the steroidogenic enzymes CYP11A1 and HSD3B2 were down-regulated (by 56% and 38%, respectively). Remarkably, treatment of GC cultures with E2 revealed its ineffectiveness in regulating the expression of several key endocrine genes (e.g., GREB1 or BCL2) in PCOS. Additionally, a comparison of the steroid concentrations (measured by GC/MS) in GCs with those in FF of matched follicles demonstrated that the significant decline in the E2 concentration (by 23%) in PCOS FF was not the result of the E2 biosynthesis reduction. Overall, our study provides novel hallmarks of PCOS by highlighting the ineffective E2 signaling in GCs as well as the dysregulation in the expression of genes involved in follicular growth, which may contribute to aberrant folliculogenesis in non-hyperandrogenic women with PCOS.

Behavioral and Physiological Differences in Female Rabbits at Different Stages of the Estrous Cycle

Estrus involves a series of complex physiological signs and changes in behavior before ovulation, which play a crucial role in animal reproduction. However, there have been few studies that evaluate behaviors during the different stages of estrus cycle in female rabbits. Therefore, more detailed information is needed on distinguishing the various stages of the estrous cycle. This study explored the behavioral and physiological differences at various estrous cycle stages in female New Zealand White rabbits. The continuous recording method was employed to record the daily behaviors of twenty postpartum female rabbits during the estrous cycle. Compared with the diestrus stage, the duration of foraging and drinking behavior in estrus decreased significantly, and the frequency of grooming and biting behaviors increased (p < 0.05). Differences in reproductive hormone levels (FSH, LH, P4, and E2) and follicle development were measured at each stage via ELISA and HE staining. The FSH and LH levels showed an increasing trend and then decreased, with the lowest being in late estrus (p < 0.05). The P4 level was the lowest in estrus (p < 0.05), and E2 showed a gradually increasing trend. There was no significant difference in the number of primordial follicles at each stage, but the number of primary follicles in estrus was significantly higher than at the other stages (p < 0.05). To further understand the molecular regulation mechanism of the estrous cycle in female rabbits, we analyzed the ovarian transcription patterns of female rabbits in diestrus (D group) and estrus (E group) employing RNA-seq. A total of 967 differentially expressed genes (DEGs) were screened from the ovaries of female rabbits between the diestrus and estrus groups. A KEGG analysis of DEGs enriched in the estrogen signaling pathway, aldosterone synthesis, and secretion pathway, such as CYP19A1 and IGF1R, was performed. The rabbits' behavior, related physiological hormones, and molecular regulation also differed at different estrous cycle stages. The results provide recommendations for the adequate management practices of postpartum re-estrus and breeding female rabbits.

Tissue-specific promoters regulate the transcription of cyp19a1 in the brain-pituitary-gonad axis of Japanese eel (Anguilla japonica)

Aromatase is a key enzyme that catalyzes the biosynthesis of estrogens. Previous study indicated that putative tissue-specific promoters of the one aromatase gene (cyp19a1) may drive the differential regulatory mechanisms of cyp19a1 expression in Anguilla japonica. In the present study, for elucidating the transcription characteristics and the function of putative tissue-specific promoters of cyp19a1 in the brain-pituitary-gonad (BPG) axis during vitellogenesis, we investigated the transcriptional regulation of cyp19a1 by 17β-estrogen (E2), testosterone (T), or human chorionic gonadotropin (HCG) in A. japonica. The expression of estrogen receptor (esra), androgen receptor (ara), or luteinizing hormone receptor (lhr) was up-regulated as cyp19a1 in response to E2, T, or HCG, respectively in the telencephalon, diencephalon, and pituitary. The expression of cyp19a1 was also upregulated in the ovary by HCG or T in a dose-dependent manner. Unlike in the brain and pituitary, the expression of esra and lhr, rather than ara, was upregulated by T in the ovary. Subsequently, four primary subtypes of 5'-untranslated terminal regions of cyp19a1 transcripts and the corresponding two 5' flanking regions (promoter P.I and P.II) were identified. The P.II existed in all BPG axis tissues, whereas the P.I with strong transcriptional activity was brain- and pituitary-specific. Furthermore, the transcriptional activity of promoters, the core promoter region, and the three putative hormone receptor response elements were validated. The transcriptional activity did not change when the HEK291T cells co-transfected with P.II and ar vector were exposed to T. These results suggested that the expression of cyp19a1 was upregulated indirectly through esra and lhr rather than ara by T in the ovary, whereas the expression of cyp19a1 was upregulated directly through androgen receptor and the downstream androgen response element of tissue-specific P.I in the brain and pituitary. The results of the study reveal the regulatory mechanisms of estrogen biosynthesis and provide a reference for optimizing the technology of artificially induced maturation in eels.

Temporality of ovarian steroids and LH/FSH pulse profiles encompassing selection of the dominant follicle in heifers†

The tested hypotheses were (1) LH/FSH pulses and F2 diameter are diminished by P4 and, (2) E2 increases during the transition to deviation and alters LH/FSH pulses. On Day 5 (Day 0 = ovulation), heifers were randomized into an untreated group (HiP4, n = 11), and a prostaglandin analog treated group (NoP4, n = 10). On Day 6, a follicular wave was induced by follicle ablation. Ultrasound and blood collections were performed every 12 h from Days 7 to 11. Blood was collected every 15 min for 10 h on Day 9 (largest follicle expected to be ~7.5 mm). Estradiol was ~75% greater (0.36 ± 0.14 vs 0.63 ± 0.19 pg/mL) in heifers with F1 ≥ 7.2 mm than in heifers with F1 < 7.2 mm. The HiP4 had smaller second largest follicle (F2) diameter, lower estradiol (P = 0.06), LH pulse baseline and peak concentrations (P < 0.007), in addition to half the frequency of LH/FSH pulses (4.1 ± 0.3 vs 9.6 ± 0.7 in 10 h) than the NoP4. Within HiP4, heifers with F1 ≥ 7.2 mm had ~25% fewer (P = 0.03) LH pulses compared to heifers with F1 < 7.2 mm. In contrast, within the NoP4, heifers with F1 ≥ 7.2 mm had ~75% greater LH (P = 0.05) and FSH (P = 0.08) pulse amplitude. We propose that greater F2 diameter at deviation in low P4 is related to greater LH baseline and peak concentrations, and greater frequency of LH/FSH pulses. A greater increase in E2 after F1 reaches ~7.2 mm results in further stimulation of LH/FSH pulse amplitude. Elevated P4 not only diminished frequency of LH/FSH pulses but also converted an E2 increase into a negative feedback effect on LH/FSH pulse frequency leading to smaller F2 at deviation.

E2/ER signaling mediates the meiotic arrest of goat intrafollicular oocytes induced by follicle-stimulating hormone

The increased production of high-quality oocytes lies at the heart of the search to accelerate the reproduction of high-quality breeding livestock using assisted reproductive technology. Follicle-stimulating hormone (FSH) maintains the arrest of oocyte meiosis during early follicular development in vivo and promotes the synchronous maturation of nucleus and cytoplasm to improve oocyte quality. However, the mechanism by which FSH maintains meiotic arrest in oocytes is still not fully understood. Oocytes spontaneously resume meiosis once released from the arrested state. In this study, we isolated goat antral follicles with a diameter of 2.0-4.0 mm, cultured them in vitro either with or without added FSH, and finally collected the oocytes to observe their meiotic state. The results showed that FSH effectively inhibited the meiotic recovery of oocytes in follicles [4 h: control (n = 84) vs. with FSH (n = 86), P = .0115; 6 h: control (n = 86) vs. FSH (n = 85), P = 0.0308; and 8 h: control (n = 95) vs. FSH (n = 101), P = 0.0039]. FSH significantly inhibited the downregulation of natriuretic peptide receptor 2 (NPR2) expression and cyclic guanosine monophosphate (cGMP) synthesis during follicular culture in vitro (P < 0.05). Further exploration found that FSH promoted the synthesis of 17β-estradiol (E2) (P = .0249 at 4 h and P = .0039 at 8 h) and maintained the expression of the estrogen nuclear receptor ERβ, but not the estrogen nuclear receptor ERα during follicle culture in vitro (P = .0190 at 2 h, and P = .0100 at 4 h). In addition, E2/ER (estrogen nuclear receptors ERα and ERβ) mediated the inhibitory effect of FSH on the downregulation of NPR2 expression and cGMP synthesis, ultimately preventing the meiotic recovery of oocytes (P < .05). In summary, our study showed that FSH-induced estrogen production in goat follicles, and the E2/ER signaling pathway, both mediated meiotic arrest in FSH-induced goat oocytes.

Androgen receptor signaling regulates follicular growth and steroidogenesis in interaction with gonadotropins in the ovary during mini-puberty in mice

In females, androgens contribute to ovarian diseases such as polycystic ovarian syndrome (PCOS), but their action is also crucial for ovarian physiology, i.e., follicular growth and estradiol (E2) synthesis during reproductive life, in interaction with the gonadotropins LH and FSH. However, it is unclear whether androgens already play a role in the ovary at mini-puberty, a phase of postnatal development with active follicular growth and high E2 levels. Therefore, we analyzed the potential actions of androgens on the ovary and their possible interaction with gonadotropins during this period in mice. We used molecular-based studies and pharmacological approaches in vivo and on cultured ovaries. We found that mini-pubertal ovaries produce significant amounts of testosterone and display androgen receptor (AR) expression in growing follicles, both under the control of LH. By blocking AR signaling either in vivo or in ovarian cultures, we found that this pathway may participate in the regulation of prepubertal E2 synthesis and follicular growth, possibly by regulating the expression of a number of key intra-ovarian regulators, including FSH receptor (Fshr), the aromatase enzyme converting androgens into estrogens (Cyp19a1) and the cell cycle inhibitor p27KIP1 (Cdkn1b). We further showed that AR may stimulate FSH-mediated regulation of Cyp19a1 through its action on Fshr mRNA abundance. Overall, this work supports the idea that AR signaling is already activated in mini-pubertal ovaries to regulate E2 synthesis and follicular growth, at the interplay with LH and FSH signaling. Its early action may, thus, contribute to the implementation of early ovarian function with possible impacts on reproductive function.

Effect of elevating luteinizing hormone action using low doses of human chorionic gonadotropin on double ovulation, follicle dynamics, and circulating follicle-stimulating hormone in lactating dairy cows

Double ovulation and twin pregnancy are undesirable traits in dairy cattle. Based on previous physiological observations, we tested the hypothesis that increased LH action [low-dose human chorionic gonadotropin (hCG)] before the expected time of diameter deviation would change circulating FSH concentrations, maximum size of the second largest (F2) and third largest (F3) follicles, and frequency of multiple ovulations in lactating dairy cows with minimal progesterone (P4) concentrations. In replicate 1, multiparous, nonbred lactating Holstein dairy cows (n = 18) had ovulation synchronized. On d 5 after ovulation, all cows had their corpus luteum regressed and were submitted to follicle (≥3 mm) aspiration 24 h later to induce emergence of a new follicular wave. Cows were then randomized to NoP4 (untreated) and NoP4+hCG (100 IU of hCG every 24 h for 4 d after follicle aspiration). Ultrasound evaluations and blood sample collections were performed every 12 h for 7 d after follicle aspiration. All cows were then treated with 200 μg of GnRH to induce ovulation. In replicate 2, cows (n = 16) were resubmitted to similar procedures (i.e., corpus luteum regression, follicle aspiration, randomization, ultrasound evaluations every 12 h, GnRH 7 d after aspiration). However, cows in replicate 2 received an intravaginal P4 device that had been previously used (∼18 d). Only cows with single (n = 15) and double (n = 16) ovulations were used in the analysis. No significant differences were detected for frequency of double ovulation, follicle sizes, and FSH concentrations across replicates (NoP4 vs. LowP4 and NoP4+hCG vs. LowP4+hCG), so data were combined. Double ovulation was 40% for control cows with no hCG (CONT) and 62.5% with hCG (hCG). Double ovulation increased as the maximum size of F2 increased: <9.5 mm and 9.5-11.5 mm (7.7%) and ≥11.5 mm (94.1%). The hCG group had more cows with F2 > 11.5 (69%) than with 9.5 ≥ F2 ≤ 11.5 (25%) and F2 < 9.5 (6%). In agreement, F2 and F3 maximum size were larger in the hCG group, but FSH concentrations were lower after F1 > 8.5 mm compared with CONT. In contrast, FSH concentrations were greater before deviation (F1 closest value to 8.5 mm) in cows with double ovulations than in those with single ovulations, regardless of hCG treatment. In addition, time from aspiration to deviation was shorter in cows with double rather than single ovulation and in cows treated with hCG as a result of faster F1, F2, and F3 growth rates before diameter deviation. In conclusion, greater FSH and follicle growth before deviation seems to be a primary driver of greater frequency of double ovulation in lactating cows with low circulating P4. Moreover, the increase in follicle growth before deviation and in the maximum size of F2 during hCG treatment suggests that increased LH may also have a role in stimulating double ovulation.

Effects of grape phenolics, myricetin and piceatannol, on bovine granulosa and theca cell proliferation and steroid production in vitro

Myricetin (a flavonol) and piceatannol (a stilbenoid) are naturally occurring phenolic compounds in red wine with cardio-protective and anti-carcinogenic effects, but their potential reproductive effects have not been investigated. Thus, the present study was designed to determine if myricetin and piceatannol can directly affect ovarian function using bovine granulosa cells (GC) and theca cells (TC) as in vitro model systems to evaluate effects on cell proliferation and steroid production. In Experiment 1 and 2, myricetin and piceatannol at 30 μM blocked insulin-like growth factor 1 (IGF1)-induced progesterone production by GC without affecting GC numbers. In contrast, myricetin stimulated IGF1-induced estradiol production, whereas piceatannol at 30 μM inhibited IGF1-induced estradiol production by 90% in GC. In Experiment 3 and 4, TC androstenedione and progesterone production and TC proliferation was inhibited by myricetin and piceatannol at 30 μM. In Experiment 5, piceatannol (30 μM) reduced the Fusarium mycotoxin, beauvericin (6 μM)-induced inhibition on progesterone production and cell proliferation. Myricetin (30 μM) reduced the inhibitory effect of beauvericin on estradiol but not progesterone production or cell proliferation. In conclusion, the red wine phenols, myricetin and piceatannol, directly affected GC and TC steroidogenesis, and were able to reduce some of the inhibitory effects of beauvericin on GC function.

Impact of preovulatory estradiol concentrations on subsequent luteal function in beef cattle

It has been hypothesized that circulating concentrations of estradiol during the preovulatory period, can impact subsequent progesterone concentrations. Ovulation was synchronized in nonlactating beef cows (n = 53). Cows that exhibited estrus before gonadotrophin-releasing hormone (GnRH)-induced ovulation (d 0) had greater (p<.01) peak concentrations of estradiol compared with cows that did not express estrus (11.5 ± 0.8 vs. 6.2 ± 0.6 pg/mL), respectively, but there was no difference in ovulatory follicle size (p= .80) or interval from GnRH2 to ovulation (p=.23). Circulating concentrations of progesterone during luteal formation (d 3-7; p=.70 and p=.77) or mid-luteal phase (d 8-14; p=.39 and p=.12) were not affected by elevated periovulatory estradiol or an interaction with day. To investigate the direct influence of estradiol on luteal function, ovulation (d 0) was synchronized in nonlactating beef cows and cows were allocated to three groups (control, n = 5; vehicle injection, n = 4; or an estradiol antagonist (Fulvestrant; ICI 182,780), n = 4. Intrafollicular injection of vehicle (100 µL) or an estradiol antagonist (25 μg Fulvestrant in 100 µL) into the largest follicle occurred on d -2. Concentrations of estradiol increased (p<.0001) from d -2 to 0 but did not differ among groups (p>.50). Furthermore, plasma concentrations of progesterone on d 0 through 20 were not affected by treatment (p=.86). These results indicate that elevated preovulatory estradiol before ovulation was not required to prepare granulosa cells for luteinization or subsequent luteal progesterone secretion but did tend to impact luteal lifespan.

Single-cell RNA sequencing analysis of mouse follicular somatic cells†

Within the development of ovarian follicle, in addition to cell proliferation and differentiation, sophisticated cell-cell cross talks are established among follicular somatic cells such as granulosa cells (GCs) and theca cells. To systematically reveal the cell differentiation and signal transductions in follicular somatic cells, we collected the mouse follicular somatic cells from secondary to ovulatory stage, and analyzed the single cell transcriptomes. Having data filtered and screened, we found 6883 high variable genes in 4888 single cells. Then follicular somatic cells were clustered into 26 cell clusters, including 18 GC clusters, 4 theca endocrine cell (TEC) clusters, and 4 other somatic cell clusters, which include immune cells and Acta2 positive theca externa cells. From our data, we found there was metabolic reprogramming happened during GC differentiation. We also found both Cyp19a1 and Cyp11a1 could be expressed in TECs. We analyzed the expression patterns of genes associated with cell-cell interactions such as steroid hormone receptor genes, insulin signaling genes, and cytokine/transformation growth factor beta associated genes in all cell clusters. Lastly, we clustered the highly variable genes into 300 gene clusters, which could be used to search new genes involved in follicle development. These transcriptomes of follicular somatic cells provide us potential clues to reveal how mammals regulating follicle development and could help us find targets to improve oocyte quality for women with low fertility.

Estrogen regulates the expression of retinoic acid synthesis enzymes and binding proteins in mouse skin

Topical 17-beta-estradiol (E2) regulates the hair cycle, hair shaft differentiation, and sebum production. Vitamin A also regulates sebum production. Vitamin A metabolism proteins localized to the pilosebaceous unit (PSU; hair follicle and sebaceous gland); and were regulated by E2 in other tissues. This study tests the hypothesis that E2 also regulates vitamin A metabolism in the PSU. First, aromatase and estrogen receptors localized to similar sites as retinoid metabolism proteins during mid-anagen. Next, female and male wax stripped C57BL/6J mice were topically treated with E2, the estrogen receptor antagonist ICI 182,780 (ICI), letrozole, E2 plus letrozole, or vehicle control (acetone) during mid-anagen. E2 or one of its inhibitors regulated most of the vitamin A metabolism genes and proteins examined in a sex-dependent manner. Most components were higher in females and reduced with ICI in females. ICI reductions occurred in the premedulla, sebaceous gland, and epidermis. Reduced E2 also reduced RA receptors in the sebaceous gland and bulge in females. However, reduced E2 increased the number of retinal dehydrogenase 2 positive hair follicle associated dermal dendritic cells in males. These results suggest that estrogen regulates vitamin A metabolism in the skin. Interactions between E2 and vitamin A have implications in acne treatment, hair loss, and skin immunity.

A high-androgen microenvironment inhibits granulosa cell proliferation and alters cell identity

A naturally occurring bovine model with excess follicular fluid androstenedione (High A4), reduced fertility, and polycystic ovary syndrome (PCOS)-like characteristics has been identified. We hypothesized High A4 granulosa cells (GCs) would exhibit altered cell proliferation and/or steroidogenesis. Microarrays of Control and High A4 GCs combined with Ingenuity Pathway Analysis indicated that High A4 GCs had cell cycle inhibition and increased expression of microRNAs that inhibit cell cycle genes. Granulosa cell culture confirmed that A4 treatment decreased GC proliferation, increased anti-Müllerian hormone, and increased mRNA for CTNNBIP1. Increased CTNNBIP1 prevents CTNNB1 from interacting with members of the WNT signaling pathway thereby inhibiting the cell cycle. Expression of CYP17A1 was upregulated in High A4 GCs presumably due to reduced FOS mRNA expression compared to Control granulosa cells. Furthermore, comparisons of High A4 GC with thecal and luteal cell transcriptomes indicated an altered cellular identity and function contributing to a PCOS-like phenotype.

Dihydrotestosterone regulates oestrogen secretion, oestrogen receptor expression, and apoptosis in granulosa cells during antral follicle development

Dihydrotestosterone (DHT) is involved in the development of preantral follicles. However, the effect of DHT on the development of antral follicles has yet to be fully investigated. Herein, we used enzyme-linked immunosorbent assays, immunofluorescence assays, quantitative real time-polymerase chain reaction, immunohistochemical staining, and western blotting to investigate the effect of DHT on antral follicle development. First, we detected the concentration of DHT and the expression of the androgen receptor (AR) in different antral follicles. Second, multiple DHT concentration (10^-10-10^-7 M) were added to granulosa cells cultured in vitro to examine the influence of DHT on AR expression. Third, to study changes in the expression of oestrogen (E2) synthase and receptors during the development of antral follicles, we divided them according to their diameters into small (≤ 2 mm), medium (2-5 mm), and large (≥ 5 mm) groups. Fourth, we added DHT (10^-8 M) and flutamide (Flu, 10^-7 M) to granulosa cells to determine whether DHT regulates the expression of cytochrome P450 aromatase (CYP19A1) and the associated receptors through the AR pathway. Fifth, we tested the effect of DHT and Flu on the expression of apoptotic genes and proteins in granulosa cells. We found that AR was expressed in sheep antral follicle granulosa cells and was regulated by DHT. During antral follicle development, the concentration of E2 and the expression of CYP19A1 and E2 receptors significantly increased in granulosa cells. DHT influenced this increase, at least partially, through the AR. Moreover, DHT regulated the expression of apoptotic genes and proteins through the AR. Our study expands our knowledge on the regulatory mechanism of DHT in antral follicle development and guides further research on the androgen regulation of ovarian function.

Follicle-stimulating hormone and luteinizing hormone regulate the synthesis mechanism of dihydrotestosterone in sheep granulosa cells

Steroid hormones and receptors play important roles in female reproduction, and their expression patterns affect follicular growth and development. To examine the expression of dihydrotestosterone (DHT) synthases (5α-reductases (5α-red1 and 5α-red2)) and androgen receptor (AR) during follicular development, and the regulation of DHT signalling by follicle-stimulating hormone (FSH) and luteinizing hormone (LH), we have used enzyme-linked immunosorbent assays, quantitative real-time polymerase chain reaction, immunohistochemical staining and Western blotting to examine DHT synthesis in small (≤2 mm), medium (2-5 mm) and large (≥5 mm) sheep follicles. Expression of 5α-red1, 5α-red2 and AR was observed in ovine ovaries, and with the development of follicles, the expressions of 5α-red1 and 5α-red2 mRNA and protein increased, but the levels of AR mRNA, protein and DHT level decreased. In addition, granulosa cells were treated with FSH (0.01, 0.1 and 1 international unit (IU)/ml), LH (0.01, 0.1 and 1 IU/ml) and testosterone (T, 10^-7  M) to evaluate the effects of FSH and LH on DHT and oestradiol (E2) synthesis and 5α-red1, 5α-red2 and AR expression. We found that FSH and LH upregulated 5α-red1 and 5α-red2 in sheep granulosa cells, but downregulated the concentration of DHT and expression of AR. Meanwhile, FSH and LH significantly upregulated the expression of aromatase (P450arom) and secretion of E2. This result indicates that although FSH and LH promote the expression of 5α-red1 and 5α-red2, T is not transformed into DHT, but E2. This study reveals the reason why DHT concentration is downregulated in large follicles and lays a foundation for further exploring the synthesis mechanism of DHT during follicular development.

Effects of DDT, DDE, aldrin and dieldrin on prostaglandin, oxytocin and steroid hormone release from smooth chorion explants of cattle

Chlorooganic xenobiotics (XBs) such as DDT, DDE, aldrin and dieldrin interfere with release of hormones from chorionic villi that are necessary for sustaining the normal course pregnancy: prostaglandins (PGs), oxytocin (OT), progesterone (P₄) and estradiol (E₂). Approximately 20 %-40 % of these hormones originate from the smooth chorion. The aim of current studies was to investigate effects of these XBs on synthesis and release of PGE₂, PGF_2α, OT, P₄ and E₂ from explants of smooth chorion of cattle, obtained during the120-150 and 151-180 day gestational period. Explants were incubated with DDT, DDE, aldrin or dieldrin at concentrations of 1 and 10 ng/mL for 24 h, and concentrations of PGE₂, PGF_2α, OT, P₄ and E₂ in post incubation medium and the relative abundances of COX-2, PTGES, AKR1B1, NP-I/OT, PAM, HSD3B, and CYP19A1 mRNA transcripts in tissue explants were determined. The XBs did not have effects on cell viability in explants (P > 0.05), however, there were effects on prostaglandins, OT and P₄ secretion and relative abundance of mRNA transcript for genes encoding the main enzymes involved in synthesis of these hormones (P < 0.05). The XBs that were evaluated did not have effects on E₂ synthesis and secretion (P > 0.05). In summary, XBs evaluated in the present study had effects on the pattern of prostaglandin secretion, and can increase OT and P₄ release from smooth chorion explants. Because XBs inhibit hormonal action throughout the chorion, there is an increase in risk of abortions or premature births in animals.

The Benefits of Testosterone Therapy in Poor Ovarian Responders Undergoing In Vitro Fertilisation (IVF)

Introduction: Poor ovarian responders are the most challenging patients in reproductive medicine and no successful treatment has been proposed. Androgens are thought to play an important role during early folliculogenesis and diminished levels are associated with decreased ovarian sensitivity to follicle-stimulating hormone. This study aimed to determine whether pretreatment with testosterone improves the results in poor responders undergoing in vitro fertilisation (IVF). Materials and methods: This observational pilot study enrolled 33 poor responders undergoing IVF. Eleven patients were pretreated with 250 mg intramuscular testosterone and compared to a control group of 22 patients. The participants were tested for free testosterone, dehydroepiandrosterone sulfate, sex hormone binding globulin, and anti-mullerian hormone (AMH). Results: The two groups had similar baseline characteristics. Significant improvement was reached in the hormones free testosterone, dehydroepiandrosterone sulfate, and sex hormone binding globulin in the testosterone-pretreatment group. No difference was detected in antral follicle count (5.06 versus 4.24); AMH (0.51 versus 0.53), mature oocytes (2.2 versus 2.32), and the number of embryos (1.2 versus 1.33) between the study and control groups, respectively. There was a slow improvement in fertilisation rate but without any significance (62.97% versus 57.61%). However, the cancellation rate of the ovarian stimulation was much greater in the control group (18.18%) in comparison with the study group (0.0%). Pregnancy rate (PR) in the testosterone group was higher than controls (PR per cycle: 27.3% versus 4.6; p=0.09). Conclusion: Based on the limited number of patients studied, pretreatment with testosterone seems to improve PR and cancellation rate in poor responders but failed to affect antral follicle count, AMH, and the number of mature oocytes and embryos. Given these results, further research would provide more certainty.

Using High-Density SNP Array to Reveal Selection Signatures Related to Prolificacy in Chinese and Kazakhstan Sheep Breeds

Selection signature provides an efficient tool to explore genes related to traits of interest. In this study, 176 ewes from one Chinese uniparous breed and three Kazakhstan multiparous breeds are genotyped using Affymetrix 600K HD single nucleotide polymorphism (SNP) arrays, F-statistics (Fst), and a Cross Population Extend Haplotype Homozygosity Test (XPEHH). These are conducted to identify genomic regions that might be under selection in three population pairs comprised the one multiparous breed and the uniparous breed. A total of 177 and 3072 common selective signatures were identified by Fst and XPEHH test, respectively. Nearly half of the common signatures detected by Fst were also captured by XPEHH test. In addition, 1337 positive and 1735 common negative signatures were observed by XPEHH in three Kazakhstan multiparous breeds. In total, 242 and 798 genes were identified in selective regions and positive selective regions identified by Fst and XPEHH, respectively. These genes were further clustered in 50 gene ontology (GO) functional terms and 66 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways in enrichment analysis. The GO terms and pathways were relevant with reproductive processes, e.g., oxytocin signaling pathway, thyroid hormone synthesis and GnRH signaling pathway, vascular smooth muscle contraction and lipid metabolism (alpha-Linolenic acid metabolism and Linoleic acid metabolism), etc. Based on the findings, six potential candidate genes ESR1, OXTR, MAPK1, RYR1, PDIA4, and CYP19A1, under positive selection related to characteristics of multiparous sheep breeds were revealed. Our results improve our understanding of the mechanisms of selection that underlies the prolificacy trait in sheep, and provide essential references for future sheep breeding.

Hormonal mechanisms regulating follicular wave dynamics II: Progesterone decreases diameter at follicle selection regardless of whether circulating FSH or LH are decreased or elevated

Selection of a single dominant follicle is morphologically manifested by diameter deviation between the future dominant follicle (F1) and the future largest subordinate follicle (F2). Conventional deviation is defined as F2≥7 mm when F1 reaches ∼8.5 mm whereas, undersized deviation is if F2<7 mm when F1 reaches ∼8.5 mm. Greater frequency of undersized deviation has been temporally associated with greater circulating progesterone (P4) and greater FSH but reduced LH in observational studies. Experiment 1 was conducted to directly test if elevating P4 increased the likelihood of undersized deviation and altered circulating concentrations of LH and FSH. Experiment 2 was conducted to test if increasing LH action by treatment with exogenous porcine LH or human chorionic gonadotropin (hCG) in the presence of elevated P4, would stimulate growth of F2 and increase the likelihood of conventional deviation. Ovaries were evaluated by ultrasound and blood samples collected every 12 h after development of a new wave following follicle ablation on D6 (D0 = ovulation). Data were normalized to F1≥7.5 mm and compared using SAS software. In experiment 1 (n = 20), the CL was regressed by prostaglandin F2α treatment and heifers were randomized on D6 into control (no P4 treatment) or P4 treatment (75 mg every 12 h for 5.5 d) beginning when F1 reached ∼3 mm (P4-3 mm group) or ∼6 mm (P4-6 mm group). The P4 treatment significantly increased the frequency of undersized deviation from 0% (controls) to 54%, decreased LH by 44%, and increased FSH by 32%. In experiment 2 (n = 27) heifers were randomized on D6 into control (saline) or treatment with the LH analogs - pLH (1.25 mg porcine LH/12 h) or hCG (160 IU initially and subsequently 96 IU/24 h). Treatment with LH analogs significantly increased P4 (control, 4.6 ± 0.3 ng/mL; pLH, 6.6 ± 0.4 ng/mL; and hCG, 8.9 ± 0.4 ng/mL) and decreased FSH (control, 0.46 ± 0.03 ng/mL; combined-pLH/hCG, 0.34 ± 0.02 ng/mL). However, F1 and F2 diameter and frequency of conventional (37%) and undersized (48%) deviations were similar between the control and combined-pLH/hCG groups. In conclusion, elevated P4 was directly linked to undersized deviation but the P4 effect on decreasing F2 diameter occurred independently of the P4 effects on FSH and LH concentrations.

Relationships between the antral follicle count, steroidogenesis, and secretion of follicle-stimulating hormone and anti-Müllerian hormone during follicular growth in cattle

BACKGROUND

The antral follicle count (AFC) in mammalian ovaries positively correlates with female fertility. To clarify the causes of differences in fertility between low and high AFC cows, we investigated follicular growth dynamics and hormone concentrations in plasma, follicular fluid, and in vitro growth (IVG) media at different stages of follicular growth.

METHODS

Seven cows were divided into high AFC (n = 4, > 30 follicles) and low AFC (n = 3, < 30 follicles) groups based on the peak AFC detected by ultrasonography. These cows were subjected to estrous synchronization, daily ovarian ultrasonography, and blood collection. Their follicular fluid was collected from dominant follicles at different stages (selection, luteal, and ovulatory phases). In another experiment, we cultured oocyte-cumulus-granulosa cell complexes collected from early antral follicles (< 1 mm) for 12 days. Estradiol-17β (E₂), testosterone (T), progesterone (P₄), and anti-Müllerian hormone (AMH) concentrations in follicular fluids and plasma were measured. Plasma follicle-stimulating hormone (FSH) concentrations were examined. E₂, P₄, and AMH concentrations were also measured in IVG media.

RESULTS

The numbers of small (< 4 mm) and intermediate (4-8 mm) follicles were larger in the high AFC group than in the low AFC group (P < 0.05). The number of intermediate follicles was stable in the low AFC group, indicating consistent development. However, the number of these follicles fluctuated in the high AFC group. Plasma FSH concentrations were higher, whereas E₂ and T concentrations were lower in the low AFC group (P < 0.05). E₂ concentrations and the E₂/P₄ ratio in ovulatory follicles and IVG media on day 8 were higher in the high AFC group (P < 0.05). AMH concentrations in plasma and IVG media (P < 0.01) were higher in the high AFC group.

CONCLUSIONS

The weaker response to FSH of granulosa cells caused low E₂ production in the low AFC group, resulting in high FSH concentrations and the consistent development of intermediate follicles. Conversely, higher E₂ concentrations suppressed FSH secretion in the high AFC group. Granulosa cells in the high AFC group had the ability to produce more AMH than those in the low AFC group throughout IVG culture.

A pilot study on polycystic ovarian syndrome caused by neonatal exposure to tributyltin and bisphenol A in rats

The development of polycystic ovary syndrome (PCOS) could be caused by exposure to environmental endocrine disrupting chemicals (EDCs). In the current study, two commonly found EDCs, bisphenol A (BPA) and tributyltin (TBT), were investigated for their effects on PCOS occurrence in neonatal female rats. TBT (10 and 100 ng kg^-1 d^-1), BPA (50 μg kg^-1 d^-1), and a mixture of the two (TBT 100 ng kg^-1 d^-1 with BPA 50 μg kg^-1 d^-1) were administered to female rats from postnatal day 1-16. TBT, BPA, and TBT + BPA treatment resulted in an irregular estrus cycle and disturbed ovarian development, with less corpora lutea and antral follicles, but more atretic follicles and cysts. In addition, serum testosterone and luteinizing hormone levels were significantly elevated, whereas a reduced level of serum sex hormone-binding globulin was observed after TBT100, BPA50, and TBT + BPA treatments. Moreover, gene expression analyses identified significant differential expression of the genes involved in a variety of biological pathways, such as lipid transport and steroidogenesis. Moreover, the expression level of proteins regulating lipid and androgen biosynthesis was elevated after the treatments. In conclusion, this study demonstrated that exposure to TBT, BPA, and a mixture of the two in newborn rats could contribute to a PCOS-like syndrome. The mechanism of PCOS pathogenesis caused by exposure to TBT and BPA is likely to be mediated by the lipid metabolism and steroidogenesis pathways. Our results provide novel insight into female reproduction affected by EDCs, which may be helpful for revealing the pathogenesis of PCOS.

Efficacy of electroacupuncture in regulating the imbalance of AMH and FSH to improve follicle development and hyperandrogenism in PCOS rats

Polycystic ovary syndrome (PCOS) is characterized by hyperandrogenism and follicular arrest. These two characteristics may result from an imbalance between anti-Müllerian hormone and follicle stimulating hormone. Electroacupuncture is effective in improving hyperandrogenism and follicular arrest in PCOS; however, the mechanism is not sufficiently clear. This study aimed to elucidate whether electroacupuncture in PCOS is exerted by regulating an imbalance of anti-Müllerian hormone and follicle stimulating hormone. In this study, a rat model of polycystic ovary syndrome was treated with low-frequency electroacupuncture at acupoints (CV-3 and CV-4). To observe the mechanism of electroacupuncture in PCOS, we first observed the estrous cycle. We then observed ovarian morphology by hematoxylin-eosin staining and evaluated levels of testosterone, estradiol, P450arom, follicle stimulating hormone and its receptor, and anti-Müllerian hormone and its receptor by enzyme-linked immunosorbent assay, western blotting, double immunofluorescence assay and real-time PCR. Our results showed that in 80% of rats in the electroacupuncture acupoints group, their estrous cycle recovered, ovarian morphology significantly improved, testosterone level significantly decreased, and levels of estradiol and P450arom significantly increased in peripheral serum after 14 consecutive days of treatment (P < 0.01). The expression of anti-Müllerian hormone and anti-Müllerian hormone type II receptor decreased (P < 0.05), whereas the expression of follicle stimulating hormone receptor increased (P < 0.05). These results indicated that electroacupuncture improved hyperandrogenism and follicular arrest by decreasing the excessive expression of AMH to regulate FSH and AMH imbalance in granulosa cells in PCOS.

Randomized, Controlled Pilot Study of Low-Dose Human Chorionic Gonadotropin Administration Beginning From the Early Follicular Phase for Women With Polycystic Ovarian Syndrome Undergoing Ovarian Stimulation Using the Progesterone Protocol

Purpose: To illustrate whether low-dose human chorionic gonadotropin (hCG) administration during the early follicular phase could reduce the number of large preovulatory follicles in women with polycystic ovarian syndrome (PCOS) undergoing ovarian stimulation using the progesterone protocol. Methods: We performed a randomized, controlled pilot trial at a university-affiliated tertiary hospital. A total of 40 infertile women undergoing their first in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment with the freeze-all strategy were included. Human menopausal gonadotropin (hMG) and progesterone soft capsule 100 mg/d were added simultaneously beginning from menstrual cycle day 3 for all participants. Low-dose hCG (200 IU) was injected every 3 days in the study group from the first day of ovarian stimulation until trigger. The primary outcome was the number of large preovulatory follicles. Secondary outcomes included the incidence of ovarian hyperstimulation syndrome (OHSS); the number of oocytes retrieved, mature oocytes, and good-quality embryos; and clinical results after frozen-thawed embryo transfer (FET) cycles. Results: The study group had slightly more large preovulatory follicles than the control group (17.75 ± 10 vs. 13.2 ± 5.34; P > 0.05). None of the participants experienced severe OHSS. There were no statistically significant differences in the number of oocytes retrieved (15.9 ± 8.46 vs. 15.75 ± 6.96), mature oocytes (13.55 ± 6.56 vs. 13.4 ± 6.34), and good-quality embryos (5.5 ± 3.41 vs. 4.9 ± 2.99) between the two groups (P > 0.05). Clinical pregnancy rates (65.52 vs. 41.94%; P = 0.067) and live birth rates (48.28 vs. 35.48%; P = 0.315) per transfer following FET of the study group were higher than those of the control group, but without statistical significance. Conclusions: Administration of low-dose hCG from the early follicular phase for PCOS patients undergoing ovarian stimulation with progesterone protocol may lead to slightly more early preovulatory follicles and marginally, but not significantly, higher clinical pregnancy rates. A continuous trial should be performed to explore the effects of supplementation with different doses of hCG from the start of ovarian stimulation in PCOS patients using the progesterone protocol. Clinical Trial Registration: Chictr.org.cn, identifier: ChiCTR-IOR-15007165.

Production and validation of a polyclonal serum against bovine FSH receptor

In ovarian granulosa cells, follicle-stimulating hormone (FSH) regulates the proliferation and differentiation events required for follicular growth and oocyte maturation. FSH actions are mediated exclusively through the FSH receptor (FSHR). In cattle, the FSHR gene expression pattern during folliculogenesis and the implications of this receptor in reproductive disorders have been extensively studied. However, the limited availability of specific antibodies against bovine FSHR has restricted FSHR protein analysis. In the present study, we developed an anti-FSHR polyclonal serum by using a 14-kDa peptide conjugated to maltose binding protein. The antiserum obtained was characterized by western blot of protein extracts from bovine follicles, BGC-1 cells and primary cultures of granulosa cells stimulated with testosterone. Also, the blocking effect of serum on estradiol secretion and cell viability after gonadotropin stimulus was characterized in a functional in vitro assay. A 76-kDa protein, consistent with the predicted molecular size of full-length FSHR, was detected in ovarian tissue. Besides, two immunoreactive bands of 60-kDa and 30-kDa (only in cultured cells) were detected. These bands would be related to some of the isoforms of the receptor. Therefore, immunohistochemical assays allowed detecting FSHR in the cytoplasm of granulosa cells and an increase in its expression as follicles progressed from primordial to large preantral follicles. These results suggest that the anti-FSHR serum here developed has good reactivity and specificity against the native FSHR. Therefore, this antiserum may serve as a valuable tool for future studies of the biological function of FSHR in physiological conditions as well as of the molecular mechanism and functional involvement of FSHR in reproductive disorders.

Luteinizing Hormone Facilitates Antral Follicular Maturation and Survival via Thecal Paracrine Signaling in Cattle

LH supplementation in assisted reproductive technology cycles improves the ongoing pregnancy rate in women with poor ovarian response (POR). However, our knowledge of the precise role of LH during the follicular phase of the menstrual cycle is incomplete. To explore the role of LH in the maturation of small antral follicles, we used an in vitro two-cell system that involved coculturing bovine granulosa cells (GCs) and theca cells (TCs) on a collagen membrane. Treatment of TCs with LH stimulated androgen production in TCs by inducing the expression of androgenic factors, subsequently increasing estrogen biosynthesis in GCs by providing androgen substrates, and inducing aromatase expression. LH stimulation of TCs induced functional LH receptor expression in GCs, a response modulated by the synthesis and action of estrogen. In the presence of TCs, LH stimulation of TCs and FSH stimulation of GCs increased the expression of IGF-1, IGF-2, and IGF-1 receptor in GCs. LH-induced expression of thecal IGF-1 protected GCs from apoptosis and promoted GC survival. Furthermore, LH stimulation of TCs increased FSH sensitivity in GCs. Thus, the LH-TC axis may be involved in the acquisition of LH dependence and the survival of small antral follicles by upregulating androgen/estrogen biosynthesis and activating the IGF system. The use of LH supplementation in ovarian stimulation may increase gonadotropin sensitivity in small antral follicles and promote follicular growth and survival by suppressing GC apoptosis and follicular atresia, resulting in multiple follicular development, even in patients with POR.

Identification of Steroidogenic Components Derived From Gardenia jasminoides Ellis Potentially Useful for Treating Postmenopausal Syndrome

Estrogen-stimulating principles have been demonstrated to relieve postmenopausal syndrome effectively. Gardenia jasminoides Ellis (GJE) is an herbal medicine possessing multiple pharmacological effects on human health with low toxicity. However, the therapeutic effects of GJE on the management of postmenopausal syndrome and its mechanism of action have not been fully elucidated. In this study, network pharmacology-based approaches were employed to examine steroidogenesis under the influence of GJE. In addition, the possibility of toxicity of GJE was ruled out and four probable active compounds were predicted. In parallel, a chromatographic fraction of GJE with estrogen-stimulating effect was identified and nine major compounds were isolated from this active fraction. Among the nine compounds, four of them were identified by network pharmacology, validating the use of network pharmacology to predict active compounds. Then the phenotypic approaches were utilized to verify that rutin, chlorogenic acid (CGA) and geniposidic acid (GA) exerted an estrogen-stimulating effect on ovarian granulosa cells. Furthermore, the results of target-based approaches indicated that rutin, CGA, and GA could up-regulate the FSHR-aromatase pathway in ovarian granulosa cells. The stimulation of estrogen production by rat ovarian granulosa cells under the influence of the three compounds underwent a decline when the follicle-stimulating hormone receptor (FSHR) was blocked by antibodies against the receptor, indicating the involvement of FSHR in the estradiol-stimulating activity of the three compounds. The effects of the three compounds on estrogen biosynthesis- related gene expression level were further confirmed by Western blot assay. Importantly, the MTT results showed that exposure of breast cancer cells to the three compounds resulted in reduction of cell viability, demonstrating the cytotoxicity of the three compounds. Collectively, rutin, chlorogenic acid and geniposidic acid may contribute to the therapeutic potential of GJE for the treatment of postmenopausal syndrome.

Reproductive Alterations in Chronically Exposed Female Mice to Environmentally Relevant Doses of a Mixture of Phthalates and Alkylphenols

Endocrine-disrupting chemicals (EDCs) are exogenous compounds that modify hormone biosynthesis, causing adverse effects to human health. Among them, phthalates and alkylphenols are important due to their wide use in plastics, detergents, personal care products, cosmetics, and food packaging. However, their conjoint effects over reproductive female health have not been addressed. The aim of this work was to test the effect of chronically exposed female mice to a mixture of three phthalates [bis (2-ethylhexyl), dibutyl, and benzyl butyl] and two alkylphenols (4-nonylphenol and 4-tert-octylphenol) from conception to adulthood at environmentally relevant doses. These EDCs were administered in two doses: one below the minimal risk dose to cause adverse effects on human development and reproduction [1 mg/kg body weight (BW)/d of the total mixture] and the other one based on the reference value close to occupational exposure in humans (10 mg/kg BW/d of the total mixture). Our results show that both doses had similar effects regarding the uterus and ovary relative weight, estrous cyclicity, serum levels of progesterone and 17β-estradiol, and expression of key elements in the steroidogenesis pathway (acute steroidogenic regulatory protein and CYP19A1). However, only the 1-mg/kg BW/d dose delayed the onset of puberty and the transition from preantral to antral follicles, whereas the 10-mg/kg BW/d dose decreased the number of antral follicles and gonadotropin receptor expression. In addition, we observed changes in several fertility parameters in exposed females and in their progeny (F2 generation). In conclusion, our results indicate that chronic exposure to a complex EDC mixture, at environmentally relevant doses, modifies reproductive parameters in female mice.

Effects of vitamin D on ovary in DHEA-treated PCOS rat model: A light and electron microscopic study

AIM

The aim of this study was to investigate the effects of vitamin D treatment on ovary in experimentally designed polycystic ovary syndrome of female rats using light and electron microscopic techniques.

METHODS

Twenty-four female pre-pubertal rats were divided into control, DHEA and DHEA+Vit.D groups. In DHEA group, the PCOS rat model was developed by 6mg/kg/day dehydroepiandrosterone administration as subcutaneously injections. In DHEA+Vit.D group, 6 mg/kg/day DHEA and 120ng/100g/week 1,25(OH)2D3 was performed simultaneously. Controls were injected with vehicle alone. At the end of the 28 days, blood samples were collected and the ovarian tissues were taken for histological examinations.

RESULTS

FSH, LH levels, LH/FSH ratio, and testosterone levels showed a significant increase in DHEA group when compared with the control group. Moreover, these measurements were lower in the treatment group than the DHEA group. In DHEA group, increased number of atretic follicles and cystic follicles were seen with light microscopic analysis. Cystic follicles with attenuated granulosa cell layers and thickened theca cell layers and lipid accumulation in interstitial cells were observed by electron microscope. It is observed that atretic and cystic follicles were decreased as a result of vitamin D treatment.

CONCLUSION

Our results indicate the curative role of vitamin D treatment on the androgen excess in PCOS rat model which causes abnormalities in ovarian morphology and functions. Vitamin D has positive effects on the hormonal and structural changes observed in PCOS, but it has been concluded that long-term use may be more beneficial.

Syndecan 1 represses cell growth and FSH responsiveness in human granulosa cells

Albeit devoid of intrinsic catalytic activity, the transmembrane heparan sulphate proteoglycan syndecan 1 plays critical roles in cellular processes such as extracellular matrix crosstalk, cytoskeletal organization, cell spreading, proliferation and differentiation. During the ovarian cycle, the expression of syndecan 1 in granulosa cells shows cyclic variation suggesting that it might fulfil specific roles in follicle development. To investigate its physiological roles on granulosa cells, syndecan 1 was overexpressed in human granulosa cell line KGN which retains features of granulosa cells from small antral follicle such as estradiol (E2) synthesis and low expression of functional FSH receptor (FSHR). We demonstrated that overexpression of syndecan 1 in immature granulosa cells (KGN-SDC1) induces a profound alteration in their intrinsic characteristics including enhanced spreading and attachment, both associated with a reduced growth rate. Flow cytometry analysis revealed that syndecan 1 overexpression increases the percentage of KGN cells in quiescent phase. This partial cell cycle exit is concordant with downregulated levels of CCND1 and CDK4 and upregulated expression of CDK inhibitor CDKN1A. In parallel both unstimulated and FSH-induced E2 synthesis are reduced in KGN-SDC1 through both repression of CYP19A1 and FSHR mRNA associated with decreased levels of potential regulators NR5A1 and ESR2. Additionally, we provide evidence that transient cAMP accumulation reduction in cells overexpressing syndecan 1 is accompanied by an increase in cAMP-hydrolysing PDE activity. Our results demonstrated that syndecan 1 might regulate differentiation of granulosa cells and follicular development by means of various mechanisms involving morphological changes, control of signalling pathways and alterations in gene expressions.

Free French abstract: A French translation of this abstract is freely available at http://www.reproduction-online.org/content/153/6/797/suppl/DC2

Stable reference genes in granulosa cells of bovine dominant follicles during follicular growth, FSH stimulation and maternal aging

The aim of the present study was to determine a set of reference genes in granulosa cells of dominant follicles that are suitable for relative gene expression analyses during maternal and follicular aging. Granulosa cells of growing and preovulatory dominant follicles were collected from aged and young cows (maternal aging study) and from FSH-stimulated follicles developing under different durations of FSH treatment (follicular aging study). The mRNA levels of the two commonly used reference genes (GAPDH, ACTB) and four novel genes (UBE2D2, EIF2B2, SF3A1, RNF20) were analysed using cycle threshold values. Results revealed that mRNA levels of GAPDH, ACTB, EIF2B2, RNF20, SF3A1 and UBE2D2 were similar (P>0.05) between dominant follicle type, age and among follicles obtained after FSH-stimulation, but differed (P=0.005) due to mRNA processing (i.e. with versus without amplification). The stability of reference genes was analysed using GeNorm, DeltaCT and NormFinder programs and comprehensive ranking order was determined using RefFinder. The mRNA levels of GAPDH and ACTB were less stable than those of UBE2D2 and EIF2B2. The geometric mean of multiple genes (UBE2D2, EIF2B2, GAPDH and SF3A1) is a more appropriate reference control than the use of a single reference gene to compare relative gene expression among dominant and FSH-stimulated follicles during maternal and/or follicular aging studies.

Interactions between androgens, FSH, anti-Müllerian hormone and estradiol during folliculogenesis in the human normal and polycystic ovary

BACKGROUND

Androgens, FSH, anti-Müllerian hormone (AMH) and estradiol (E2) are essential in human ovarian folliculogenesis. However, the interactions between these four players is not fully understood.

OBJECTIVES AND RATIONALE

The purpose of this review is to highlight the chronological sequence of the appearance and function of androgens, FSH, AMH and E2 and to discuss controversies in the relationship between FSH and AMH. A better understanding of this interaction could supplement our current knowledge about the pathophysiology of the polycystic ovary syndrome (PCOS).

SEARCH METHODS

A literature review was performed using the following search terms: androgens, FSH, FSH receptor, anti-Mullerian hormone, AMHRII, estradiol, follicle, ovary, PCOS, aromatase, granulosa cell, oocyte. The time period searched was 1980-2015 and the databases interrogated were PubMed and Web of Science.

OUTCOMES

During the pre-antral ('gonadotropin-independent') follicle growth, FSH is already active and promotes follicle growth in synergy with theca cell-derived androgens. Conversely, AMH is inhibitory by counteracting FSH. We challenge the hypothesis that AMH is regulated by androgens and propose rather an indirect effect through an androgen-dependent amplification of FSH action on granulosa cells (GCs) from small growing follicles. This hypothesis implies that FSH stimulates AMH expression. During the antral ('gonadotropin-dependent') follicle growth, E2 production results from FSH-dependent activation of aromatase. Conversely, AMH is inhibitory but the decline of its expression, amplified by E2, allows full expression of aromatase, characteristic of the large antral follicles. We propose a theoretical scheme made up of two triangles that follow each other chronologically. In PCOS, pre-antral follicle growth is excessive (triangle 1) because of intrinsic androgen excess that renders GCs hypersensitive to FSH, with consequently excessive AMH expression. Antral follicle growth and differentiation are disturbed (triangle 2) because of the abnormally persisting inhibition of FSH effects by AMH that blocks aromatase. Beside anovulation, this scenario may also serve to explain the higher receptiveness to gonadotropin therapy and the increased risk of ovarian hyperstimulation syndrome (OHSS) in patients with PCOS.

WIDER IMPLICATIONS

Within GCs, the balance between FSH and AMH effects is pivotal in the shift from androgen- to oestrogen-driven follicles. Our two triangles hypothesis, based on updated data from the literature, offers a pedagogic template for the understanding of folliculogenesis in the normal and polycystic ovary. It opens new avenues for the treatment of anovulation due to PCOS.

Bovine ovarian cells have (pro)renin receptors and prorenin induces resumption of meiosis in vitro

The discovery of a receptor that binds prorenin and renin in human endothelial and mesangial cells highlights the possible effect of renin-independent prorenin in the resumption of meiosis in oocytes that was postulated in the 1980s.This study aimed to identify the (pro)renin receptor in the ovary and to assess the effect of prorenin on meiotic resumption. The (pro)renin receptor protein was detected in bovine cumulus-oocyte complexes, theca cells, granulosa cells, and in the corpus luteum. Abundant (pro)renin receptor messenger ribonucleic acid (mRNA) was detected in the oocytes and cumulus cells, while prorenin mRNA was identified in the cumulus cells only. Prorenin at concentrations of 10(-10), 10(-9), and 10(-8)M incubated with oocytes co-cultured with follicular hemisections for 15h caused the resumption of oocyte meiosis. Aliskiren, which inhibits free renin and receptor-bound renin/prorenin, at concentrations of 10(-7), 10(-5), and 10(-3)M blocked this effect (P<0.05). To determine the involvement of angiotensin II in prorenin-induced meiosis resumption, cumulus-oocyte complexes and follicular hemisections were treated with prorenin and with angiotensin II or saralasin (angiotensin II antagonist). Prorenin induced the resumption of meiosis independently of angiotensin II. Furthermore, cumulus-oocyte complexes cultured with forskolin (200μM) and treated with prorenin and aliskiren did not exhibit a prorenin-induced resumption of meiosis (P<0.05). Only the oocytes' cyclic adenosine monophosphate levels seemed to be regulated by prorenin and/or forskolin treatment after incubation for 6h. To the best of our knowledge, this is the first study to identify the (pro)renin receptor in ovarian cells and to demonstrate the independent role of prorenin in the resumption of oocyte meiosis in cattle.

Transcriptome Analysis of Bovine Ovarian Follicles at Predeviation and Onset of Deviation Stages of a Follicular Wave

For two libraries (PDF1 and ODF1) using Illumina sequencing 44,082,301 and 43,708,132 clean reads were obtained, respectively. After being mapped to the bovine RefSeq database, 15,533 genes were identified to be expressed in both types of follicles (cut-off RPKM > 0.5), of which 719 were highly expressed in bovine follicles (cut-off RPKM > 100). Furthermore, 83 genes were identified as being differentially expressed in ODF1 versus PDF1, where 42 genes were upregulated and 41 genes were downregulated. KEGG pathway analysis revealed two upregulated genes in ODF1 versus PDF1, CYP11A1, and CYP19A1, which are important genes in the steroid hormone biosynthesis pathway. This study represents the first investigation of transcriptome of bovine follicles at predeviation and onset of deviation stages and provides a foundation for future investigation of the regulatory mechanisms involved in follicular development in cattle.

Localisation and endocrine control of hyaluronan synthase (HAS) 2, HAS3 and CD44 expression in sheep granulosa cells

The aim of the present study was to investigate the hormonal regulation of hyaluronan (HA) components in sheep granulosa cells. HA components are present in the reproductive tract and have a range of physical and signalling properties related to reproductive function in several species. First, abattoir-derived ovaries of sheep were used to determine the localisation of HA synthase (HAS) 1–3 and CD44 proteins in antral follicles. Staining for HAS1–3 and CD44 proteins was most intense in the granulosa layer. Accordingly, the expression of HAS2, HAS3 and CD44 mRNA was measured in cultured granulosa cells exposed to 0–50 ng mL–1 of 17β-oestradiol and different combinations of oestradiol, gonadotropins, insulin-like growth factor (IGF)-1 and insulin for 48–96 h (1 ng mL–1 FSH, 10 ng mL–1 insulin, 10 ng mL–1 IGF-1, 40 ng mL–1 E2 and 25 ng mL–1 LH.). mRNA expression was quantified by real-time polymerase chain reaction using a fold induction method. The results revealed that the hormones tested generally stimulated mRNA expression of the genes of interest in cultured granulosa cells. Specifically, oestradiol, when combined with IGF-1, insulin and FSH, stimulated HAS2 mRNA expression. Oestradiol and LH had synergistic effects in increasing HAS3 mRNA expression. In conclusion, we suggest that the hormones studied differentially regulate HAS2, HAS3 and CD44 in ovine granulosa cells in vitro. Further work is needed to address the signalling pathways involved.

Induction of chemokines and prostaglandin synthesis pathways in luteinized human granulosa cells: potential role of luteotropin withdrawal and prostaglandin F2α in regression of the human corpus luteum

Our objective was to determine the effects of prostaglandin F2α (PGF2α) and withdrawal of luteotropic stimulants (forskolin or hCG) on expression of chemokines and prostaglandin-endoperoxide synthase 2 (PTGS2) in luteinized human granulosa cells. Human granulosa cells were collected from 12 women undergoing oocyte retrieval and were luteinized in vitro with forskolin or hCG. In first experiment, granulosa-lutein cells were treated with PGF2α, the primary luteolytic hormone in most species. In second experiment, granulosa cells that had been luteinized for 8 d had luteotropins withdrawn for 1, 2, or 3 d. Treatment with PGF2α induced mRNA for chemokine (c-x-c motif) ligand 2 (CXCL2) and CXC ligand 8 (CXCL8; also known as interleukin-8) in granulosa cells luteinized for 8 d but not in cells that were only luteinized for 2 d. Similarly, luteinization of human granulosa cells for 8 d with forskolin or hCG followed by withdrawal of luteotropic stimulants, not only decreased P4 production, but also increased mRNA concentrations for CXCL8, CXCL-2 (after forskolin withdrawal), and PTGS2. These results provide evidence for two key steps in differentiation of luteolytic capability in human granulosa cells. During 8 d of luteinization, granulosa cells acquire the ability to respond to luteolytic factors, such as PGF2α, with induction of genes involved in immune function and PG synthesis. Finally, a decline in luteotropic stimuli triggers similar pathways leading to induction of PTGS2 and possibly intraluteal PGF2α production, chemokine expression, leukocyte infiltration and activation, and ultimately luteal regression.

A Novel, Stable, Estradiol-Stimulating, Osteogenic Yam Protein with Potential for the Treatment of Menopausal Syndrome

A novel protein, designated as DOI, isolated from the Chinese yam (Dioscorea opposita Thunb.) could be the first protein drug for the treatment of menopausal syndrome and an alternative to hormone replacement therapy (HRT), which is known to have undesirable side effects. DOI is an acid- and thermo-stable protein with a distinctive N-terminal sequence Gly-Ile-Gly-Lys-Ile-Thr-Thr-Tyr-Trp-Gly-Gln-Tyr-Ser-Asp-Glu-Pro-Ser-Leu-Thr-Glu. DOI was found to stimulate estradiol biosynthesis in rat ovarian granulosa cells; induce estradiol and progesterone secretion in 16- to 18-month-old female Sprague Dawley rats by upregulating expressions of follicle-stimulating hormone receptor and ovarian aromatase; counteract the progression of osteoporosis and augment bone mineral density; and improve cognitive functioning by upregulating protein expressions of brain-derived neurotrophic factor and TrkB receptors in the prefrontal cortex. Furthermore, DOI did not stimulate the proliferation of breast cancer and ovarian cancer cells, which suggest it could be a more efficacious and safer alternative to HRT.

Molecular aspects of bovine cystic ovarian disease pathogenesis

Cystic ovarian disease (COD) is one of the main causes of reproductive failure in cattle and causes severe economic loss to the dairy farm industry because it increases both days open in the post partum period and replacement rates due to infertility. This disease is the consequence of the failure of a mature follicle to ovulate at the time of ovulation in the estrous cycle. This review examines the evidence for the role of altered steroid and gonadotropin signaling systems and the proliferation/apoptosis balance in the ovary with cystic structures. This evidence suggests that changes in the expression of ovarian molecular components associated with these cellular mechanisms could play a fundamental role in the pathogenesis of COD. The evidence also shows that gonadotropin receptor expression in bovine cystic follicles is altered, which suggests that changes in the signaling system of gonadotropins could play a fundamental role in the pathogenesis of conditions characterized by altered ovulation, such as COD. Ovaries from animals with COD exhibit a disrupted steroid receptor pattern with modifications in the expression of coregulatory proteins. These changes in the pathways of endocrine action would trigger the changes in proliferation and apoptosis underlying the aberrant persistence of follicular cysts.

Free Spanish abstract: A Spanish translation of this abstract is freely available at http://www.reproduction-online.org/content/149/6/R251/suppl/DC1.

Non-canonical WNT5A is a potential regulator of granulosa cell function in cattle

The WNT family has been implicated in follicular development in rodents, however, the role of WNTs in the follicle of monovulatory species is poorly understood. The objective of this study was to determine the potential roles of WNTs in bovine granulosa cell function. Cells cultured in serum-free medium expressed mRNA encoding WNT2B, WNT5B and WNT5A. Levels of WNT5A, but not of WNT2B or WNT5B mRNA, were down-regulated by FSH. Addition of WNT5A to cultured cells suppressed FSH-stimulated estradiol and progesterone secretion, and levels of mRNA encoding the steroidogenic enzymes CYP19A1, CYP11A1 and the FSH receptor, but had no effect on cell proliferation or apoptosis. Immunoblot experiments showed that WNT5A reduced activation of CTNNB1 and stimulated phosphorylation of MAPK8 and JUN proteins. We conclude that WNT5A is a negative regulator of FSH-stimulated granulosa cell steroidogenesis, and that it acts by suppressing canonical WNT signaling activity and inducing the non-canonical MAPK8/JUN pathway.

Transcriptional profiling of five isolated size-matched stages of human preantral follicles

Little is known of the early stages of human follicular development and the complex processes that regulate follicular growth. To identify genes of potential importance, we analysed follicle-related transcripts in five populations of isolated size-matched human preantral follicles by microarray analysis. Oocyte-specific genes were found to be the most abundant and differentially expressed transcripts and included germ cell transcription factors LHX8 and SOHLH2 which were significantly down-regulated during preantral follicle development. Differentially expressed genes also included transcription factors of NOTCH signalling, IGF2, orphan nuclear receptor LRH-1, and homeobox gene HOXA7, indicating potentially important regulatory roles for these genes during early human folliculogenesis. We also found that FSHR mRNA and protein were present in the earliest stages of preantral follicles, whereas LHR was absent. In conclusion, our data identify specific oocyte and somatic genes in small human follicles that impact early follicle growth, and provide foundation for further analysis of the signalling pathways involved in early human folliculogenesis.

Expression and molecular consequences of inhibition of estrogen receptors in granulosa cells of bovine follicles

Background

Estradiol (E2) receptors mediate E2 effects on cell proliferation and apoptosis under normal and pathological conditions. However, the mechanisms involved in E2 signaling are not completely understood. The objectives in this study were to evaluate the expression of estrogen receptors (ESRs) during follicular selection in cattle, and the effect of intrafollicular injection of fulvestrant (an antagonist of ESRs) on follicular development and transcript abundance in granulosa cells.

Methods

Granulosa cells were obtained from the two largest follicles around follicular deviation, after FSH treatment and after intrafollicular injection of fulvestrant. Ovarian follicular dynamics monitored by ultrasonography and quantitative real time PCR were used to validate the in vivo model and investigate the effects of FSH supplementation or ESR blockade on mRNA expression of estradiol-related genes.

Results

ESR1 and ESR2 were expressed in granulosa cells of both dominant (F1) and subordinate (F2) follicles, but their transcripts levels were higher in F1 than F2 after follicular deviation. FSH treatment maintained mRNA levels of both ESR1 and ESR2 in F2 follicles at similar levels observed in F1 follicles. Intrafollicular injection of 100 μM fulvestrant inhibited follicular growth and decreased CYP19A1 mRNA levels. Transcript levels for both ESR1 and ESR2 were not affected by fulvestrant injection. Analyses of FSH-regulated genes revealed that ESRs inhibition in the dominant follicle decreased the transcript levels of the GJA1 but not those of PRKAR2B, MRO or LRP11 genes.

Conclusions

Our findings indicate that: both ESR1 and ESR2 are regulated during follicular deviation and dominance in cattle and in response to FSH treatment, and ESRs are required for normal gene expression and development of the dominant follicle. Furthermore, we have validated an in vivo model to study estrogen signaling during follicular development that allows paracrine signaling between different follicular cells in a physiological endocrine environment.

1,25-Dihydroxyvitamin D3 increases testosterone-induced 17beta-estradiol secretion and reverses testosterone-reduced connexin 43 in rat granulosa cells

BACKGROUND

Aromatase converts testosterone into 17beta-estradiol in granulosa cells, and the converted 17beta-estradiol contributes to follicular maturation. Additionally, excessive testosterone inhibits aromatase activity, which can lead to concerns regarding polycystic ovary syndrome (PCOS). Generally, 1,25-dihydroxyvitamin D3 (1,25D3) supplements help to improve the symptoms of PCOS patients who exhibit low blood levels of 1,25D3. Therefore, this study investigated the interaction effects of 1,25D3 and testosterone on estrogenesis and intercellular connections in rat granulosa cells.

METHODS

Primary cultures of granulosa cells were treated with testosterone or testosterone plus 1,25D3, or pre-treated with a calcium channel blocker or calcium chelator. Cell lysates were subjected to western blot analysis to determine protein and phosphorylation levels, and 17beta-estradiol secretion was examined using a radioimmunoassay technique. Cell viability was evaluated by MTT reduction assay. Connexin 43 (Cx43) mRNA and protein expression levels were assessed by qRT-PCR, western blot, and immunocytochemistry.

RESULTS

Testosterone treatment (0.1 and 1 microg/mL) increased aromatase expression and 17beta-estradiol secretion, and the addition of 1,25D3 attenuated testosterone (1 microg/mL)-induced aromatase expression but improved testosterone-induced 17beta-estradiol secretion. Furthermore, testosterone-induced aromatase phosphotyrosine levels increased at 10 min, 30 min and 1 h, whereas 1,25D3 increased the longevity of the testosterone effect to 6 h and 24 h. Within 18-24 h of treatment, 1,25D3 markedly enhanced testosterone-induced 17beta-estradiol secretion. Additionally, pre-treatment with a calcium channel blocker nifedipine or an intracellular calcium chelator BAPTA-AM reduced 1,25D3 and testosterone-induced 17beta-estradiol secretion. Groups that underwent testosterone treatment exhibited significantly increased estradiol receptor beta expression levels, which were not affected by 1,25D3. Neither testosterone nor 1,25D3 altered 1,25D3 receptor expression. Finally, at high doses of testosterone, Cx43 protein expression was decreased in granulosa cells, and this effect was reversed by co-treatment with 1,25D3.

CONCLUSIONS

These data suggest that 1,25D3 potentially increases testosterone-induced 17beta-estradiol secretion by regulating aromatase phosphotyrosine levels, and calcium increase is involved in both 1,25D3 and testosterone-induced 17beta-estradiol secretion. 1,25D3 reverses the inhibitory effect of testosterone on Cx43 expression in granulosa cells.

Androgen actions in the ovary: balance is key

For many decades, elevated androgens in women have been associated with poor reproductive health. However, recent studies have shown that androgens play a crucial role in women's fertility. The following review provides an overall perspective about how androgens and androgen receptor-mediated actions regulate normal follicular development, as well as discuss emerging concepts, latest perceptions, and controversies regarding androgen actions and signaling in the ovary.

mRNA expression pattern of gonadotropin receptors in bovine follicular cysts

Follicular growth and steroidogenesis are dependent on gonadotropin binding to their receptors in granulosa and theca cells of ovarian follicles. The aim of the present study was to evaluate the expression patterns of follicle-stimulating hormone receptor (FSHR) and luteinizing hormone receptor (LHCGR) in ovarian follicular structures from cows with cystic ovarian disease (COD) as compared with those of regularly cycling cows. Relative real-time RT-PCR analysis showed that the expression of FSHR mRNA in granulosa cells was highest in small antral follicles, then decreased significantly as follicles increased in size, and was lowest in cysts. FSHR mRNA was not detected in the theca cells of any follicular category, including cysts. LHCGR mRNA expression in granulosa cells was significantly higher in large antral follicles than in cysts, and not detected in granulosa cells of small and medium antral follicles. In theca cells, the expression level of LHCGR mRNA in medium antral follicles was higher than in small and large antral follicles, whereas that in follicular cysts it was similar to those in small and medium antral follicles, but higher than that in large antral follicles. Our findings provide evidence that there is an altered gonadotropin receptor expression in bovine cystic follicles, and suggest that in conditions characterized by altered ovulation, such as COD, changes in the signaling system of gonadotropins may play a fundamental role in their pathogenesis.

Regulation and regulatory role of WNT signaling in potentiating FSH action during bovine dominant follicle selection

Follicular development occurs in wave like patterns in monotocous species such as cattle and humans and is regulated by a complex interaction of gonadotropins with local intrafollicular regulatory molecules. To further elucidate potential mechanisms controlling dominant follicle selection, granulosa cell RNA harvested from F1 (largest) and F2 (second largest) follicles isolated at predeviation (PD) and onset of diameter deviation (OD) stages of the first follicular wave was subjected to preliminary RNA transcriptome analysis. Expression of numerous WNT system components was observed. Hence experiments were performed to test the hypothesis that WNT signaling modulates FSH action on granulosa cells during follicular waves. Abundance of mRNA for WNT pathway members was evaluated in granulosa cells harvested from follicles at emergence (EM), PD, OD and early dominance (ED) stages of the first follicular wave. In F1 follicles, abundance of CTNNB1 and DVL1 mRNAs was higher and AXIN2 mRNA was lower at ED versus EM stages and DVL1 and FZD6 mRNAs were higher and AXIN2 mRNA was lower in F1 versus F2 follicle at the ED stage. Bovine granulosa cells were treated in vitro with increasing doses of the WNT inhibitor IWR-1+/- maximal stimulatory dose of FSH. IWR-1 treatment blocked the FSH-induced increase in granulosa cell numbers and reduced the FSH-induced increase in estradiol. Granulosa cells were also cultured in the presence or absence of FSH +/- IWR-1 and hormonal regulation of mRNA for WNT pathway members and known FSH targets determined. FSH treatment increased CYP19A1, CCND2, CTNNB1, AXIN2 and FZD6 mRNAs and the stimulatory effect on CYP19A1 mRNA was reduced by IWR-1. In contrast, FSH reduced CARTPT mRNA and IWR-1 partially reversed the inhibitory effect of FSH. Results support temporal and hormonal regulation and a potential role for WNT signaling in potentiating FSH action during dominant follicle selection.

The rate of high ovarian response in women identified at risk by a high serum AMH level is influenced by the type of gonadotropin

The aim was to compare ovarian response and clinical outcome of potential high-responders after stimulation with highly purified menotropin (HP-hMG) or recombinant follicle-stimulating hormone (rFSH) for in vitro fertilisation/intracytoplasmic sperm injection. Retrospective analysis was performed on data collected in two randomized controlled trials, one conducted following a long GnRH agonist protocol and the other with an antagonist protocol. Potential high-responders (n = 155 and n = 188 in the agonist and antagonist protocol, respectively) were defined as having an initial anti-Müllerian hormone (AMH) value >75th percentile (5.2 ng/ml). In both protocols, HP-hMG stimulation in women in the high AMH category was associated with a significantly lower occurrence of high response (≥15 oocytes retrieved) than rFSH stimulation; 33% versus 51% (p = 0.025) and 31% versus 49% (p = 0.015) in the long agonist and antagonist protocol, respectively. In the potential high-responder women, trends for improved live birth rate were observed with HP-hMG compared with rFSH (long agonist protocol: 33% versus 20%, p = 0.074; antagonist protocol: 34% versus 23%, p = 0.075; overall population: 34% versus 22%, p = 0.012). In conclusion, the type of gonadotropin used for ovarian stimulation influences high-response rates and potentially clinical outcome in women identified as potential high-responders.