Ovarian Follicular Maturation Research Articles

The Expression Pattern of Insulin-Like Growth Factor Subtype 3 (igf3) in the Orange-Spotted Grouper Epinephelus coioides and Its Function on Ovary Maturation.

A new insulin-like growth factor (Igf) subtype 3 (igf3) has recently been found in the bony fish orange-spotted grouper (Epinephelus coioides). However, the role of igf3 in the maturation of the ovary and sex differentiation in E. coioides is currently unknown. We examined the ovarian localization and receptor binding of the novel ortholog Igf3 using qRT-PCR, and Western blotting, combined with in situ hybridization and immunohistochemistry methods. Results demonstrated the presence of igf3 mRNA and protein in mature oocytes. Furthermore, Igf3 protein expression was not detected in testis, brain, kidney and liver homogenates. The calculated molecular weight of Igf3 was 22 kDa, which was consistent with the deduced amino acid sequence from the full-length open reading frame. The immunoreactivity showed that Igf3 was strongly present in the follicle staining fully-grown stage. The igf3 mRNA expression level was significantly positively correlated with ovarian follicular maturation. Meanwhile, Igf3 increased germinal-vesicle breakdown in a time- and dose-dependent manner. In vitro, treatment of primary ovarian cells with Igf3 up-regulated significantly the mRNA expression level of genes related to sex determination and reproduction such as forkhead boxl2 (foxl2), dosage-sensitive sex reversal adrenal hypoplasia critical region on chromosome x gene 1 (dax1), cytochrome P450 family 19 subfamily member 1 a (cyp19a1a), cytochrome P450 family 11 subfamily a member 1 a (cyp11a1a) and luteinizing hormone receptor 1 (lhr1). Overall, our results demonstrated that igf3 promotes the maturation of the ovary and plays an important role in sex differentiation in E. coioides.

Extended LH administration as a strategy to increase the pool of recruitable antral follicles in hypothalamic amenorrhea: evidence from a case series.

New evidence is indicating a growing role of LH in promoting ovarian follicular growth and maturation, even at the early stages. LH seems to enhance the transition of follicles to the antral stage hence leading to an increase in the so-called functional ovarian reserve (recruitable antral follicles). Hypogonadotropic hypogonadism is characterized by low, and sometimes undetectable, serum LH and FSH levels, which may indeed explain the low anti-Müllerian hormone (AMH) levels and antral follicle count (AFC) found in patients affected by this condition. We report here the cases of two young women affected by hypothalamic amenorrhea (HA) that presented for fertility treatment with very low functional ovarian reserve. The two patients were treated with exogenous LH for 1 and 2 months (extended LH administration: ELHA) at the dose of 187.5 IU LH every day and 150 IU LH every other day, respectively. In both the cases there was an increase in serum AMH levels and in the AFC. In one patient, the AMH and AFC increased from a baseline 1.3 ng/ml and 8 to 2.3 ng/ml and 14 at end of treatment, respectively. In the second case, serum AMH and AFC increased from 0.4 ng/ml and 6 to 1.6 ng/ml and 13, respectively. One patient underwent ovarian stimulation before and after ELHA, showing an increase in the number of mature oocytes recruited (3 versus 8 metaphase II (MII) oocytes before and after, respectively). The second patient underwent an IVF cycle after ELHA resulting in the retrieval of six MII oocytes and an ongoing pregnancy following transfer of a single blastocyst. Women with HA are characterized by chronic, low levels of gonadotrophins, which may impact not only on the cyclic recruitment of follicles but also the progression of small growing follicles through the first stages of folliculogenesis. Some women with HA may in fact show very low serum AMH and AFC. Our case series shows that the administration of LH at a dose of at least 150-187.5 IU every day or every other day may contribute to a clinically evident increase in the functional ovarian reserve (AFC), and probably accounts for a positive effect of LH on the progression of follicles throughout the early stages of folliculogenesis.

PITX2 regulates steroidogenesis in granulosa cells of dairy goat by the WNT/β-catenin pathway

Paired-like homeodomain transcription factor 2 (PITX2), a major driver of multiple tissue development, is a transcription factor that regulates gene expression in organisms. However, it is unknown if PITX2 regulates goat granulosa cell (GC) steroidogenesis. Therefore, we investigated the role and mechanism of PITX2 in GC steroidogenesis. In our study, PITX2 significantly facilitated the secretion level of estrogen and progesterone through increasing CYP11A1, CYP19A1, and STAR mRNA and protein expressions in GCs. Furthermore, PITX2 participated in the WNT pathway, enhancing the production of E2 and P4 in GCs. PITX2 in GCs increased the DVL-1 and CTNNB1 expression, involved in the WNT/β-catenin signaling pathway related to steroidogenesis. Moreover, GC steroidogenesis-related gene translation was decreased by CTNNB1-siRNA but enhanced when transfected with PITX2. PITX2 regulates secretion of E2 and P4 from GCs via the WNT/β-catenin pathway and alters GC proliferation and steroidogenesis. These findings will help understand the role of PITX2 in goat ovarian follicular development and oocyte maturation.

The two-step process of ovarian follicular growth and maturation in mammals can be compared to a fruit ripening where quality depends on the second step.

In human in vitro fertilization, the main uncertainty factor impacting on success is oocyte quality, which largely depends on the follicular status at the time of collection. Decades of debate ensued to find the perfect stimulation protocol demonstrated the complexity of the ovarian response to exogenous gonadotropins and the dynamic nature of late folliculogenesis. Although several follicular markers, proteins, RNA from granulosa cells or microRNA, and follicular fluid metabolites have been associated with outcome, the possibility to influence them during stimulation remains elusive. The heterogeneity of the follicle's maturity following control ovarian stimulation is also an important factor to explain average poor oocyte quality still observed today. In this review, the analogy between the apple ripening on the tree and follicular development is presented to focus the attention on a biphasic process: growth and differentiation. The molecular analysis of the progressive follicular differentiation indicates two competing phenomena: growth and differentiation, where a delicate balance must operate from one to the other to ensure proper maturity at ovulation. As long as follicle-stimulating hormone (FSH) stimulates growth, follicles remain green, and it is only when FSH is replaced by luteinizing hormone that the ripening process begins, and "apples" become red. Both fruits, follicles and apples, depend on a perfect timing of events to generate offspring.

Protective effects of dichloroacetic acid on endometrial injury and ovarian reserve in an experimental rat model of diabetes mellitus

To study (1) ovarian and endometrial damage caused by the hyperglycemia and (2) the effects of dichloroacetic acid (DCA) on follicular reserve and endometrial damage in streptozocin induced diabetic rats. This study consisted 24 rats randomly separated into three groups. A diabetes model was achieved in 16 rats experimentally, and normoglycemic eight rats were assigned as control group (Group 1). The rats with diabetes were randomly separated to two groups: 1 mL/kg/day intraperitoneal 0.9% NaCl was given to eight rats as diabetic vehicle (Group 2) and 10mg/kg/day DCA was given to other eight rats as DCA treated group (Group 3). Hysterectomy with bilateral oophorectomy was performed for histopathological evaluation and blood samples were collected after 4 weeks. Diabetes caused ovarian and endometrial damage (p < 0.0001). Pentraxin-3 (PTX-3), lactic acid, and transforming growth factor-beta (TGF-β) were higher (p < 0.05, p < 0.05, and p < 0.0001, respectively), whereas anti-Mullerian hormone (AMH) was lower in diabetic rats (p < 0.05). These findings reflected the diabetic damage in the genital tract and diminished ovarian reserve occurred via fibrosis, severe inflammation, and oxidative stress. DCA improved the histopathological fibrosis and degeneration in the ovaries and endometrium (p < 0.05). There was a concominant decrease of TGF-β and lactic acid levels with DCA treatment (p < 0.05). DCA also improved ovarian reserve with higher AMH levels (p < 0.05). The several unfavored changes in the endometrium and ovaries due to diabetes have been determined in this present study. DCA might provide the continuity of the endometrial cycle, physiological endometrial structure, ovarian follicular growth, oocyte maturation, and physiological ovarian function by decreasing the lactate levels via inhibiting pyruvate dehydrogenase kinase enzyme.

MicroRNA 195-5p Targets Foxo3 Promoter Region to Regulate Its Expression in Granulosa Cells.

Forkhead box O3 (Foxo3) is a member of the FOXO subfamily within the forkhead box (FOX) family, which has been shown to be essential for ovarian follicular development and maturation. Previous studies have shown the abundant expression of miR-195-5p in the nuclei of porcine granulosa cells (GCs), suggesting its potential role during ovarian follicle growth. In this study, a conditional immortalized porcine granulosa cell (CIPGC) line was used to determine whether the expression of Foxo3 could be regulated by the nuclear-enriched miR-195-5p. Through silico target prediction, we identified a potential binding site of miR-195-5p within the Foxo3 promoter. The over-expression of miR-195-5p increased Foxo3 expression at both mRNA and protein levels, while the knockdown of miR-195-5p decreased the expression of Foxo3. Furthermore, driven by the Foxo3 promoter, luciferase reporter activity was increased in response to miR-195-5p, while the mutation of the miR-195-5p binding site in the promoter region abolished this effect. In addition, the siRNA knockdown of Argonaute (AGO) 2, but not AGO1, significantly decreased Foxo3 transcript level. However, miR-195-5p failed to upregulate Foxo3 expression when AGO2 was knocked down. Moreover, chromatin immunoprecipitation (CHIP) assay showed that anti-AGO2 antibody pulled down both AGO2 and the Foxo3 promoter sequence, suggesting that AGO2 may be required for miR-195-5p to regulate Foxo3 expression in the nucleus. Additionally, Foxo3 expression was significantly increased by valproic acid (VPA), the inhibitor of deacetylase, as well as by methyltransferase inhibitor BIX-01294, indicating the involvement of histone modification. These effects were further enhanced in the presence of miR-195-5p and were decreased when miR-195-5p was knocked down. Overall, our results suggest that nuclear-enriched miR-195-5p regulates Foxo3 expression, which may be associated with AGO2 recruitment, as well as histone demethylation and acetylation in ovarian granulosa cells.

Vitamin D in follicular development and oocyte maturation.

Vitamin D (VD) is a secosteroid hormone synthesized predominantly in the skin upon UV light exposure, which can also be obtained from dietary sources. In target cells, the bioactive VD binds to specific VD receptor to regulate downstream transcription of genes that are involved in a wide range of cellular processes. There is an increasing recognition that the proper physiological levels of VD are critical for optimizing reproductive potential in women. The direct VD action in the ovary was first suggested in the 1980s. Since then, research has attempted to determine the role of VD in follicular development and oocyte maturation in animal models and clinical settings. However, data published to date are inconclusive due to the complexity in VD metabolism and the fact that VD actions are pervasive in regulating physiological functions in various systems, including the reproductive, endocrine and nervous systems that control reproduction. This review summaries in vitro, in vivo, and clinical evidence regarding VD metabolism and signaling in the ovary, as well as VD-regulated or VD-associated ovarian follicular development, steroidogenic function, and oocyte maturation. It is suggested that adequate animal models are needed for well-controlled studies to unravel molecular mechanisms of VD action in the ovary. For clinical studies, follicular development and function may be evaluated more effectively in a relatively homogeneous patient population under a well-controlled experimental design. A comprehensive understanding of VD-regulated folliculogenesis and oogenesis will provide critical insight into the impact of VD in female reproductive health.

Should I Lay or Should I Grow: Photoperiodic Versus Metabolic Cues in Chickens.

While photoperiod has been generally accepted as the primary if not the exclusive cue to stimulate reproduction in photoperiodic breeders such as the laying hen, current knowledge suggests that metabolism, and/or body composition can also play an influential role to control the hypothalamic-pituitary gonadal (HPG)-axis. This review thus intends to first describe how photoperiodic and metabolic cues can impact the HPG axis, then explore and propose potential common pathways and mechanisms through which both cues could be integrated. Photostimulation refers to a perceived increase in day-length resulting in the stimulation of the HPG. While photoreceptors are present in the retina of the eye and the pineal gland, it is the deep brain photoreceptors (DBPs) located in the hypothalamus that have been identified as the potential mediators of photostimulation, including melanopsin (OPN4), neuropsin (OPN5), and vertebrate-ancient opsin (VA-Opsin). Here, we present the current state of knowledge surrounding these DBPs, along with their individual and relative importance and, their possible downstream mechanisms of action to initiate the activation of the HPG axis. On the metabolic side, specific attention is placed on the hypothalamic integration of appetite control with the stimulatory (Gonadotropin Releasing Hormone; GnRH) and inhibitory (Gonadotropin Inhibitory Hormone; GnIH) neuropeptides involved in the control of the HPG axis. Specifically, the impact of orexigenic peptides agouti-related peptide (AgRP), and neuropeptide Y (NPY), as well as the anorexigenic peptides pro-opiomelanocortin (POMC), and cocaine-and amphetamine regulated transcript (CART) is reviewed. Furthermore, beyond hypothalamic control, several metabolic factors involved in the control of body weight and composition are also presented as possible modulators of reproduction at all three levels of the HPG axis. These include peroxisome proliferator-activated receptor gamma (PPAR-γ) for its impact in liver metabolism during the switch from growth to reproduction, adiponectin as a potential modulator of ovarian development and follicular maturation, as well as growth hormone (GH), and leptin (LEP).

Effect of Oocyte Quality Assessed by Brilliant Cresyl Blue (BCB) Staining on Cumulus Cell Expansion and Sonic Hedgehog Signaling in Porcine during In Vitro Maturation.

Brilliant cresyl blue (BCB) staining is used to select developmentally competent cumulus-oocyte complexes (COCs) for in vitro maturation (IVM). However, limited attention has been paid to what drives the higher developmental competence of BCB+ COCs. Sonic hedgehog signaling (SHH) is an important signaling pathway for ovarian follicular development and oocyte maturation. Therefore, this study investigated the effect of oocyte quality assessed by BCB staining on cumulus cell expansion, oocyte nuclear maturation, subsequent embryo development, apoptosis levels, and SHH signaling protein expression, in porcine COCs. After IVM, BCB+ COCs exhibited a significantly higher proportion of complete cumulus cell expansion and metaphase II rate in oocytes than BCB- COCs. After in vitro fertilization, the BCB+ group showed a significantly higher monospermy rate, fertilization efficiency, percentage of cleavage and blastocyst formation, with a higher total cell number and a lower apoptosis in blastocysts as compared with the BCB- group. Furthermore, significantly lower apoptosis levels and a higher expression of SHH-signaling proteins in COCs were observed, before and after IVM. In conclusion, high-quality oocytes had a greater potential to expand their surrounding cumulus cells with active SHH signaling and a lower apoptosis. This could provide COCs with a proper environment for maturation, thereby leading to a better subsequent embryo development.

Single-Cell Transcriptomic Analysis Reveals Mitochondrial Dynamics in Oocytes of Patients With Polycystic Ovary Syndrome.

Polycystic ovary syndrome (PCOS), characterized by polycystic ovarian morphology, ovarian follicular maturation arrest, and hormonal disorders, affects numerous women in the reproductive age worldwide. A recent study has found that mitochondria are likely to play an essential role in oocyte quality. However, it is still unclear whether oocyte development failure is associated with mitochondria in patients with PCOS. We analyzed the single-cell RNA sequencing data from the previous study, including data from 14 oocytes from 7 healthy fertile women and 20 oocytes from 9 patients with PCOS at the germinal vesicle (GV) stage, metaphase I (MI) stage, and metaphase II (MII) stage. We revealed the transcriptomic dynamics by weighted gene co-expression network analysis (WGCNA) and investigated the differences between stages using PCA and Deseq2 analyses to identify the differential expression genes (DEGs). Gene ontology (GO) was performed using clusterProfiler R package and Metascape. Our results indicated that specific gene modules were related to different stages of oocyte development using WGCNA. Functional enrichment analysis and gene co-expression network analysis found significant enrichment of the mitochondrial regulation genes at the GV stage. PCA (principal component analysis) and differential gene expression analysis suggested that GV was significantly different from the MI and MII stages between the two groups. Further analysis demonstrated that the upregulated differentially expressed genes at the GV stage of patients with PCOS mainly related to mitochondrial function, such as COX6B1, COX8A, COX4l1, and NDUFB9. Meanwhile, these genes tended to be activated at the MII stage in healthy cells, suggesting that some mitochondrial functions may be prematurely activated at the GV stage of PCOS oocytes, whereas this process occurs at the MII stage in healthy oocytes. Collectively, our study showed that aberrant mitochondrial function at the GV stage may contribute to a decline in oocyte quality of PCOS patients.

Evaluation the Serum Level of Melatonin in Iraqi Patients with Polycystic Ovarian Syndrome

Background: Polycystic Ovarian Syndrome(PCOS) is one of the most frequent gynecological endocrinopathy that occur in premenopausalfemales, with a predominance range from 6%to10% among women of reproductive age.Melatonin (N-acetyl-5-methoxytryptamine), an neurohormone synthesized from the aromatic amino acid tryptophan mainly by the pineal gland of humans.The important of melatonin in human reproduction is still unidentified. A numerous study suggests that melatonin and reproductive hormones are closely related. This concept is based on observation of influence melatonin on sex steroid production at different stages of ovarian follicular maturation as melatonin receptors have been demonstrated at multiple sites in ovary and in intrafollicular fluid. Aim :The study aim to evaluate the role of melatonin in women with polycystic ovarian syndrome. Materials and Methods:A prospective cross-sectional study was designed taking 60 PCOS patients and 30 controls women whose ages were between 15-35 years old, from beginning of January 2019 to ending of April 2019. These patients admitted to obstetrics and gynecology unit at Babylon teaching hospital. And Five ml of blood sample was taken on day 2 of menstrual cycle by vein puncture from each subject enrolled in this study .Blood samples were collected between 07:00am – 08:00 am, and placed into sterile test tubes to serum melatonin estimation.Result: The study showed that there is the significant difference betweenPCOS women and the control group concerning melatonin level,and the highest mean of melatonin was occurred in PCOS women (61.21±13.78vs. 28.61±6.73). And also This study showed that there were the higher means of melatonin in PCOS women with positive family history than PCOS women with negative family history (66.56±11.25vs. 59.26±14.21) with significant relation.Conclusions: Women with PCOS have significant increase of serum melatonin in PCOS women. And also thisstudy could open the way for therapeutic role of melatonin in treatment of PCOS women.

Sirt3 is dispensable for oocyte quality and female fertility in lean and obese mice.

Mammalian oocytes rely heavily on mitochondrial oxidative phosphorylation (OXPHOS) for generating ATP. However, mitochondria are also the primary source of damaging reactive oxygen species (ROS). Mitochondrial de-regulation, therefore, underpins poor oocyte quality associated with conditions such as obesity and aging. The mitochondrial sirtuin, Sirt3, is critical for mitochondrial respiration and redox regulation. Interestingly, however, Sirt3 knockout (Sirt3-/- ) mice do not exhibit systemic compromise under basal conditions, only doing so under stressed conditions such as high-fat diet (HFD)-induced obesity. Mouse oocytes depleted of Sirt3 exhibit increased ROS in vitro, but it is unknown whether Sirt3 is necessary for female fertility in vivo. Here, we test this for the first time by investigating ovarian follicular reserve, oocyte maturation (including detailed spindle assembly and chromosome segregation), and female fertility in Sirt3-/- females. We find that under basal conditions, young Sirt3-/- females exhibit no defects in any parameters. Surprisingly, all parameters also remain intact following HFD-induced obesity. Despite markedly increased ROS levels in HFD Sirt3-/- oocytes, ATP levels nevertheless remain normal. Our data support that ATP is sustained in vivo through increased mitochondrial mass possibly secondary to compensatory upregulation of another sirtuin, Sirt1, which has overlapping functions with Sirt3.

The role of melatonin in polycystic ovary syndrome: A review.

BackgroundPolycystic ovary syndrome (PCOS) is a widespread endocrine disorder, affecting approximately 20% of women within reproductive age. It is associated with hyperandrogenism, obesity, menstrual irregularity, and anovulatory infertility. Melatonin is the main pineal gland hormone involved in the regulation of the circadian rhythm. In recent years, it has been observed that a reduction in melatonin levels of follicular fluid exists in PCOS patients. Melatonin receptors in the ovary and intra-follicular fluid adjust sex steroid secretion at different phases of ovarian follicular maturation. Moreover, melatonin is a strong antioxidant and an effective free radical scavenger, which protects ovarian follicles during follicular maturation.ObjectiveIn this paper, we conducted a literature review and the summary of the current research on the role of melatonin in PCOS.Materials and MethodsElectronic databases including PubMed/MEDLINE, Web of Science, Scopus, and Reaxys were searched from their inception to October 2018 using the keywords “Melatonin” AND “Polycystic ovary syndrome” OR “PCOS.”ResultsBased on the data included in our review, it was found that the administration of melatonin can improve the oocyte and embryo quality in PCOS patients. It may also have beneficial effects in correcting the hormonal alterations in PCOS patients.ConclusionSince metabolic dysfunction is the major finding contributing to the initiation of PCOS, melatonin can hinder this process via its improving effects on metabolic functions.

Toll-like receptors and high mobility group box 1 in granulosa cells during bovine follicle maturation.

Toll-like receptors (TLRs) are present in the ovaries and reproductive tract of various mammals. The biological function of TLR during ovulation is one of the main contents in the research of reproductive immunology. In this study, we found that messenger RNA levels of TLR1-TLR10 in granulosa cells were different, and TLRs and high mobility group box 1 (HMGB1) in granulosa cells of large follicles were significantly higher than those of small and middle follicles. Coimmunoprecipitation results showed that HMGB1 interacts with TLR2 in granulosa cells, especially large follicles. The result of immunohistochemistry showed that TLRs and HMGB1 were present in granulosa cell layer of ovarian follicles. We also found 25 mIU/ml follicle-stimulating hormone (FSH) significantly upregulated the expression of TLRs and HMGB1. These results suggest that TLR2/4 and HMGB1 in granulosa cells may be involved in the ovarian innate immune and ovarian follicular maturation, regulated by FSH. However, further research of the function and mechanisms of TLRs and HMGB1 in granulosa cells are needed.

Antimicrobial peptide expression in swine granulosa cells in response to lipopolysaccharide

Antimicrobial peptides (AMP) are host defense peptides present in all species examined. The objective of the current study was to characterize the expression of a group of antimicrobial peptides in ovarian cells, and to investigate their expression response to pathogen ligands. It was found that while PG1 transcript was not detected in the ovary, the expression of BD2 is the highest in small follicle derived granulosa cells (SGC), and its expression decreases during follicular development to large follicle stage (LGC; p < 0.05). The expression of BD2 in cumulus cells also decreased from GV to MII stage of oocyte maturation. ANG4 expression increased in granulosa cells during follicular development from SGC to LGC stage (p < 0.05), although no significant difference was observed in cumulus cells from different stages of oocyte maturation. We further examined AMP expression in follicle cells treated with different toll-like receptor (TLR) ligands which mimic pathogen exposure in the ovary. Of the four TLR ligands examined, lipopolysaccharide (LPS) exposure resulted in a 11.5 fold increase of BD2 expression, and a significant decrease of LYZ in LGC. A similar response pattern in BD2 and LYZ expression was also observed in SGC. These responses of AMP expression to LPS are associated with increased TLR4 signaling pathway component in mRNA and protein level, such as MyD88 and NFkB, and pro-inflammatory cytokines/chemokines, such as IL-6, TNFα and IL-8 (p < 0.05). Our data suggest that AMPs may play a role in innate defense as well as other physiological functions during ovarian follicular development and oocyte maturation.

Whole-cell biopanning with a synthetic phage display library of nanobodies enabled the recovery of follicle-stimulating hormone receptor inhibitors

Antibodies are essential reagents that are increasingly used in diagnostics and therapy. Their specificity and capacity to recognize their native antigen are critical characteristics for their in vivo application. Follicle-stimulating hormone receptor is a GPCR protein regulating ovarian follicular maturation and spermatogenesis. Recently, its potentiality as a cancer biomarker has been demonstrated but no antibody suitable for in vivo tumor targeting and treatment has been characterized so far. In this paper we describe the first successful attempt to recover recombinant antibodies against the FSHR and that: i) are directly panned from a pre-immune library using whole cells expressing the target receptor at their surface; ii) show inhibitory activity towards the FSH-induced cAMP accumulation; iii) do not share the same epitope with the natural binder FSH; iv) can be produced inexpensively as mono- or bivalent functional molecules in the bacterial cytoplasm. We expect that the proposed biopanning strategy will be profitable to identify useful functional antibodies for further members of the GPCR class.

Gonadotropin-Dependent Neuregulin-1 Signaling Regulates Female Rat Ovarian Granulosa Cell Survival.

Mammalian ovarian follicular development and maturation of an oocyte competent to be fertilized and develop into an embryo depends on tightly regulated, spatiotemporally orchestrated crosstalk among cell death, survival, and differentiation signals through extra- and intraovarian signals, as well as on a permissive ovarian follicular microenvironment. Neuregulin-1 (NRG1) is a member of the epidermal growth factor-like factor family that mediates its effects by binding to a member of the erythroblastoma (ErbB) family. Our experimental results suggest gonadotropins promote differential expression of NRG1 and erbB receptors in granulosa cells (GCs), and NRG1 in theca cells during follicular development, and promote NRG1 secretions in the follicular fluid (FF) of rat ovaries. During the estrous cycle of rat, NRG1 and erbB receptors are differentially expressed in GCs and correlate positively with serum gonadotropins and steroid hormones. Moreover, in vitro experimental studies suggest that the protein kinase C inhibitor staurosporine (STS) causes the physical destruction of GCs by the activation of caspase-3. Exogenous NRG1 treatment of GCs delayed onset of STS-induced apoptosis and inhibited cleaved caspase-3 expressions. Moreover, exogenous NRG1 treatment of GCs alters STS-induced death by maintaining the expression of ErbB2, ErbB3, pAkt, Bcl2, and BclxL proteins. Taken together, these studies demonstrate that NRG1 is gonadotropin dependent, differentially regulated in GCs and theca cells, and secreted in ovarian FF as an intracellular survival factor that may govern follicular maturation.

GOSSYPOL PROMOTES THE DEGENERATION OF CHICKEN OVARIAN FOLLICLES IN VITRO

Gossypol, a phenolic compound produced by the pigment glands of cotton, is known to affect male reproduction. In females, exposure to gossypol has been associated with interference with the estrous cycle and embryo development. In laying hens fed cottonseed, gossypol was found to reduce egg production and weight and to cause discoloration of the egg yolk and/or albumen. It is probable that gossypol directly affects ovarian follicles, but this has not been confirmed experimentally yet. Thus, the aim of the present study was to determine if gossypol affected cultivated ovarian follicles of the chicken. Ovarian follicles of adult female chickens were cultivated with different concentrations of gossypol (0, 5, 10 and 20 μg/mL) and classified according to the stage of development as primordial, transitional, primary, secondary or antral, and as viable or atretic. The percentages of viable and atretic follicles in the ovaries cultivated for 24 hours in the presence of gossypol were significantly different from those of the controls for all types of follicles except for secondary follicles, but in all types after cultivation for 7 days. The percentage of viable follicles was higher than that of atretic follicles in ovaries cultivated without gossypol. In contrast, ovaries cultivated with gossypol showed a predominance of atretic follicles. Gossypol increased the proportion of atretic follicles at all stages of development in cultivated chicken ovaries. Thus, gossypol may affect ovarian follicular viability and maturation, which might interfere with female fertility.

Different transcriptional levels of GABAA receptor subunits in mouse cumulus cells around oocytes at different mature stage

γ-Aminobutyric acid (GABA) is a principal inhibitory neurotransmitter in the central nervous system (CNS) of vertebrates. However, GABA and its receptor are found not only in peripheral neuronal tissue but also in many peripheral nonneuronal tissues, and thought to have multiple physiological functions. The bidirectional communication between oocytes and cumulus cells (CCs) plays a significant role in oocyte maturation and metabolism. In our previously study, the expression level of α5 subunit in CCs isolated from oocytes of patients with polycystic ovary syndrome had been found to be associated with oocyte nuclear maturity. In this study, we investigated the transcriptional levels of GABAA receptor subunits in germinal vesicle (GV) and metaphase II (MII) mouse CCs, and explored the role of GABA-A receptor subunits during ovarian follicular development and oocyte maturation. We found that GABAA receptor subunits exhibited differential transcriptional levels in CCs at different oocyte nuclear maturity stages. It suggested an involvement of GABA-A receptor subunits related to oocyte maturation and certain functions.

The effect of androgens on ovarian follicle maturation: Dihydrotestosterone suppress FSH-stimulated granulosa cell proliferation by upregulating PPARγ-dependent PTEN expression.

Intraovarian hyperandrogenism is one of the determining factors of follicular arrest in women with polycystic ovary syndrome (PCOS). Using androgenized rat models, we investigated the effects of androgens on metabolism, as well as on factors involved in follicular arrest and the reduced number of estrus cycles. The dihydrotestosterone (DHT)-treated rats had fewer estrus cycles, higher numbers of large arrested follicles and an increased in body weight gain compared with the dehydroepiandrostenedione (DHEA)- and placebo-treated rats. In cultured rat granulosa cells, DHT suppressed follicle stimulating hormone (FSH)-induced granulosa cell proliferation and increased the accumulation of cells in the G2/M phase. DHT decreased phosphorylated Akt (p-Akt) and cyclin D1 levels through increasing PTEN. DHT-promoted PTEN expression was regulated by peroxisome proliferator-activated receptor gamma (PPARγ) in granulosa cells. Meanwhile, in the large follicles of the DHT-treated rats, the expressions of PPARγ and PTEN were higher, but the expression of p-Akt and proliferating cell nuclear antigen (PCNA) were lower. Conclusively, DHT and DHEA produced differential effects on metabolism in prepubertal female rats like clinical manifestations of women with PCOS. DHT treatment may affect ovarian follicular maturation by altering granulosa cell proliferation through the regulation of enhancing PPARγ dependent PTEN/p-Akt expression in the granulosa cells.