Intrabursal injection of vascular endothelial growth factor trap in eCG-treated prepubertal rats inhibits proliferation and increases apoptosis of follicular cells involving the PI3K/AKT signaling pathway

Multiomic meta-analysis suggests a correlation between steroid hormone-related genes and litter size in goats

Litter size is a key indicator of production performance in livestock. However, its genetic basis in goats remains poorly understood. In this work, a genome-wide selection sweep analysis (GWSA) on 100 published goat genomes with different litter rates was performed for the first time to identify candidate genes related to kidding rate. This analysis was combined with the public RNA-sequencing data of ovary tissues (follicular phase) from high- and low-yielding goats. A total of 2278 genes were identified by GWSA. Most of these genes were enriched in signaling pathways related to ovarian follicle development and hormone secretion. Moreover, 208 differentially expressed genes between groups were obtained from the ovaries of goats with different litter sizes. These genes were substantially enriched in the cholesterol and steroid synthesis signaling pathways. Meanwhile, the weighted gene co-expression network was used to perform modular analysis of differentially expressed genes. The results showed that seven modules were reconstructed, of which one module showed a very strong correlation with litter size (r = -0.51 and p-value <0.001). There were 51 genes in this module, and 39 hub genes were screened by Pearson's correlation coefficient between core genes > 0.4, correlation coefficient between module members > 0.80 and intra-module connectivity ≥5. Finally, based on the results of GWSA and hub gene Venn analysis, seven key genes (ACSS2, HECW2, KDR, LHCGR, NAMPT, PTGFR and TFPI) were found to be associated with steroid synthesis and follicle growth development. This work contributes to understanding of the genetic basis of goat litter size and provides theoretical support for goat molecular breeding.

Local effect of allopregnanolone in rat ovarian steroidogenesis, follicular and corpora lutea development

Allopregnanolone (ALLO) is a known neurosteroid and a progesterone metabolite synthesized in the ovary, CNS, PNS, adrenals and placenta. Its role in the neuroendocrine control of ovarian physiology has been studied, but its in situ ovarian effects are still largely unknown. The aims of this work were to characterize the effects of intrabursal ALLO administration on different ovarian parameters, and the probable mechanism of action. ALLO administration increased serum progesterone concentration and ovarian 3β-HSD2 while decreasing 20α-HSD mRNA expression. ALLO increased the number of atretic follicles and the number of positive TUNEL granulosa and theca cells, while decreasing positive PCNA immunostaining. On the other hand, there was an increase in corpora lutea diameter and PCNA immunostaining, whereas the count of TUNEL-positive luteal cells decreased. Ovarian angiogenesis and the immunohistochemical expression of GABAA receptor increased after ALLO treatment. To evaluate if the ovarian GABAA receptor was involved in these effects, we conducted a functional experiment with a specific antagonist, bicuculline. The administration of bicuculline restored the number of atretic follicles and the diameter of corpora lutea to normal values. These results show the actions of ALLO on the ovarian physiology of the female rat during the follicular phase, some of them through the GABAA receptor. Intrabursal ALLO administration alters several processes of the ovarian morpho-physiology of the female rat, related to fertility and oocyte quality.

Deconvolution at the single-cell level reveals ovarian cell-type-specific transcriptomic changes in PCOS

BACKGROUND

Polycystic ovary syndrome (PCOS) is one of the most common reproductive endocrine disorders in females of childbearing age. Various types of ovarian cells work together to maintain normal reproductive function, whose discordance often takes part in the development and progression of PCOS. Understanding the cellular heterogeneity and compositions of ovarian cells would provide insight into PCOS pathogenesis, but are, however, not well understood. Transcriptomic characterization of cells isolated from PCOS cases have been assessed using bulk RNA-seq but cells isolated contain a mixture of many ovarian cell types.

METHODS

Here we utilized the reference scRNA-seq data from human adult ovaries to deconvolute and estimate cell proportions and dysfunction of ovarian cells in PCOS, by integrating various granulosa cells(GCs) transcriptomic data.

RESULTS

We successfully defined 22 distinct cell clusters of human ovarian cells. Then after transcriptome integration, we obtained a gene expression matrix with 13,904 genes within 30 samples (15 control vs. 15 PCOS). Subsequent deconvolution analysis revealed decreased proportion of small antral GCs and increased proportion of KRT8high mural GCs, HTRA1high cumulus cells in PCOS, especially increased differentiation from small antral GCs to KRT8high mural GCs. For theca cells, the abundance of internal theca cells (TCs) and external TCs was both increased. Less TCF21high stroma cells (SCs) and more STARhigh SCs were observed. The proportions of NK cells and monocytes were decreased, and T cells occupied more in PCOS and communicated stronger with inTCs and exTCs. In the end, we predicted the candidate drugs which could be used to correct the proportion of ovarian cells in patients with PCOS.

CONCLUSIONS

Taken together, this study provides insights into the molecular alterations and cellular compositions in PCOS ovarian tissue. The findings might contribute to our understanding of PCOS pathophysiology and offer resource for PCOS basic research.

Downregulated lncRNA HOTAIR ameliorates polycystic ovaries syndrome via IGF-1 mediated PI3K/Akt pathway

OBJECTIVE

Polycystic ovarian syndrome (PCOS) is a common disorder that leads to infertility in reproductive-aged females. HOTAIR is highly expressed in various gynecological diseases and is associated with a poor prognosis. We aimed to explore the role of HOTAIR in PCOS.

METHODS

First, PCOS rats were induced using dehydroepiandrosterone and then treated with si-HOTAIR. Next, HOTAIR mRNA expression and serum hormone levels were detected. HE staining was applied to observe estrus cycle, ovarian morphology and count the number of follicles. Apoptosis in the ovary was detected by TUNEL. Thereafter, ovarian granulosa cells (GCs) were isolated from PCOS rats, transfected with si-HOTAIR and treated with LY294002 (Akt inhibitor) or IGF-1. CCK-8 and flow cytometry assays were used to evaluate cell viability and apoptosis. IGF-1, apoptosis- and PI3K/Akt pathway-associated protein expressions in ovary and GCs were also detected.

RESULTS

In in vivo experiments, si-HOTAIR decreased serum T, E₂ and LH levels but increased FSH level, restored estrus cycle, ovarian morphology and inhibited apoptosis of ovary in PCOS rats. Meanwhile, in vitro assays showed that si-HOTAIR upregulated the viability but inhibited the apoptosis of PCOS GCs. Furthermore, both in vivo and in vitro assays revealed that si-HOTAIR increased Bcl-2 expression but suppressed Bax, Bad, IGF-1 expressions and PI3K, AKT phosphorylation. However, the aforementioned effects of si-HOTAIR in vitro were further enhanced by LY294002 and partially reversed by IGF-1.

CONCLUSIONS

HOTAIR knockdown improved PCOS, and the mechanism may relate to IGF-1-mediated PI3K/Akt pathway, indicating HOTAIR may be a novel therapeutic target for PCOS.

Functional expression of P2Y2 receptors in mouse ovarian surface epithelium (OSE)

Ovarian surface epithelium (OSE) is a cell monolayer surrounding the ovary; it is involved in the regulation of the ovulatory process and the genesis of ovarian carcinoma. However, intercellular messengers regulating signaling events, like proliferation in the OSE, have not been completely described. Purines have emerged as novel intercellular messengers in the ovary, in which expression of purinergic receptors has been reported in different cell types. In the present work, we described the functional expression of P2Y2 receptor (P2Y2R), a purinergic receptor widely associated with cell proliferation, in the OSE. The expression of P2Y2R by immunofluorescence and RT-PCR, and its functionality by Ca²⁺ recording was demonstrated in primary cultured OSE. Functional expression of P2Y2R was also exhibited in situ, by recording of intracellular Ca²⁺ release and detection of ERK phosphorylation after injection of a selective agonist into the ovarian bursa. Furthermore, P2Y2R activation with UTPγS, in situ, induced cell proliferation at 24 h, whereas continuous stimulation of P2Y2R during a complete estrous cycle significantly modified the size distribution of the follicular population. This is the first evidence of the functional expression of purinergic P2Y2R in the OSE and opens new perspectives on the roles played by purines in ovarian physiology.

Morroniside suppresses hydrogen peroxide-stimulated autophagy and apoptosis in rat ovarian granulosa cells through the PI3K/AKT/mTOR pathway

Previous evidences have indicated that granulosa cells play a critical role in follicular growth. Hydrogen peroxide (H2O2)-induced oxidative stress has been associated with ovarian granulosa cell apoptosis and ovarian function. Recently, a study highlighted the protective role of morroniside against H2O2-induced damage. In this study, we aimed to investigate the effects of morroniside on H2O2-stimulated rat ovarian granulosa cells and its underlying molecular mechanisms. Our results showed that H2O2 treatment suppressed cell survival and increased apoptosis in rat granulosa cells, while treatment with morroniside markedly increased H2O2-induced granulosa cell survival in a dose-dependent manner (0, 10, 50 and 100 µM). Moreover, treatment with 50 µM morroniside impeded H2O2-induced cell apoptosis. An elevation in intracellular ROS, MDA, SOD, GSH-Px, and CAT level was observed in H2O2-induced granulosa cells; however, this effect was abrogated by morroniside treatment. Further studies suggested that administration of morroniside inhibited H2O2-induced granulosa cell apoptosis and caspase-3 activity. In addition, after morroniside treatment of H2O2-stimulated granulosa cells, autophagy-related protein (LC3-II/LC3-I ratio) and beclin-1 expression was decreased and p62 level was increased. Interestingly, we found that morroniside treatment activated the PI3K/AKT/mTOR pathway in H2O2-stimulated granulosa cells. Finally, we showed that treatment with PI3K and mTOR inhibitors reversed the protective effects of morroniside on H2O2-induced granulosa cells. Taken together, our data suggest that treatment with morroniside decreased apoptosis, autophagy, and oxidative stress in rat granulosa cells through the PI3K/AKT/mTOR pathway.

Hypoxia up-regulates VEGF ligand and downregulates VEGF soluble receptor mRNA expression in bovine granulosa cells in vitro

Oxygen concentration (0₂) in antral ovarian follicles is below that found in most tissues, which is important for adequate granulosa cell function. The VEGF system is linked to angiogenesis and responds to changing 0₂ by stimulating neovascularization when levels are low. However, in the avascular granulosa cell layer of the follicle, VEGF action is directed to stimulating cell viability and steroidogenesis. The aim of this study was to examine the effect of 0₂ concentration on granulosa cell expression of the VEGF-system components. Bovine granulosa cells were isolated from medium-sized follicles (4-7 mm in diameter), placed in McCoy 5a medium supplemented with 10 ng/mL of insulin, 1 ng/mL of IGF-I, and 1 ng/mL of FSH, and cultured in four well plates (500 thousand cells per well), on three separate occasions. Culture plates were placed in gas-impermeable jars with a gas mixture containing either 2%, or 5% of O₂, or under atmospheric air condition inside an incubator (20% of 0₂). Media was replaced at 48 h of culture and cells from the plate in each oxygen concentration were pooled for RNA extraction after 96 h. The number of mRNA copies for the VEGF-system components - including ligands (VEGF120, VEGF120b, VEGF165 and VEGF165b), enzymes (cyclin-dependent like kinases-1, CLK1 and serine-arginine protein kinase 1, SRPK1), splicing factors (serine-arginine-rich splicing factors, SRSF1 and SRSF6), and the membrane-bound (VEGFR1, VEGFR2) and soluble forms of the receptors (sVEGFR1 and sVEGFR2) were quantified by qPCR. Granulosa cells cultured with low 0₂ (2%) had a higher expression of VEGF ligands (P < 0.05) when compared to cells cultured at 20% 0₂. VEGF164b mRNA was absent in granulosa cells from all culture conditions. The 2 and 5% 0₂ levels, which coincide with physiological concentrations, in the ovarian follicle, induced higher SRSF6 expression than atmospheric 0₂ concentrations (20%, P < 0.05). In contrast, mRNA copies for SRPK1, CLK1, SRSF1, VEGFR1 or VEGFR2 did not differ between 0₂ culture conditions. (P > 0.05). Nonetheless, mRNA copies for the soluble receptors, sVEGFR1 and sVEGFR2, linearly increased (P < 0.05) with 0₂ concentration. These results suggest that when cultured under hypoxic conditions, granulosa cells may develop an autocrine milieu that favors VEGF's biological effects on their survival and function.

miRNA-21-3p targeting of FGF2 suppresses autophagy of bovine ovarian granulosa cells through AKT/mTOR pathway

It is widely thought that the main reason for ovarian follicular atresia is apoptosis of granulosa cells, however, accumulating evidence suggests that autophagy plays a role in the fate of granulosa cells. Although epigenetic regulation including miR-21-3p associated with autophagy process has been reported in many cancer types, nevertheless, the mechanism of miR-21-3p in bovine ovary is poorly understood. In the present study, bovine ovarian granulosa cells (BGCs) were used as a model to elucidate the autophagy and role of miR-21-3p in a cattle ovary. The results from gene expression and tagged autophagosomes showed the autophagy in BGCs and miR-21-3p was identified as an important miRNA regulating autophagy of BGCs. The current results indicated that FGF2 was a validated target of miR-21-3p in autophagy regulation of BGCs according to the results from FGF2 luciferase reporter assays and FGF2 overexpression (oe-FGF2) or small interference (si-FGF2). Transfection of miR-21-3p mimic and si-FGF2 plasmids resulted in decreasing phosphorylated AKT and mTOR, while transfection of miR-21-3p inhibitor and oe-FGF2 increased the phosphorylated level of AKT and mTOR in BGCs. These data indicate that regulation of miR-21-3p on BGCs autophagy through AKT/mTOR pathway. In summary, this study suggests that miR-21-3p targets FGF2 to inhibit BGCs autophagy by repressing AKT/mTOR signaling.

Low level laser therapy (LLLT) modulates ovarian function in mature female mice

It is known that LLLT has beneficial effects on several pathological conditions including wound healing, pain and inflammation. LLLT modulates biological processes, including cell proliferation, apoptosis and angiogenesis. In the present study, we examined the effect of local application of LLLT on follicular dynamics, ovarian reserve, AMH expression, progesterone levels, apoptosis, angiogenesis, and reproductive outcome in adult mice. LLLT (200 J/cm2) increased the percentage of primary and preantral follicles, whilst decreasing the percentage of corpora lutea compared to control ovaries. LLLT-treated ovaries did not exhibit any changes regarding the number of primordial follicles. We observed a higher percentage of AMH-positive follicles (in early stages of development) in LLLT-treated ovaries compared to control ovaries. LLLT reduced the P4 concentration and the apoptosis in early antral follicles compared to control ones. LLLT caused a reduction in the endothelial cell area and an increase in the periendothelial cell area in the ovary. Additionally, LLLT was able to improve oocyte quality. Our findings suggest that local application of LLLT modulates follicular dynamics by regulating apoptosis and the vascular stability in mouse ovary. In conclusion, these data indicate that LLLT might become a novel and useful tool in the treatment of several pathologies, including female reproductive disorders.

Resveratrol promotes in vitro activation of ovine primordial follicles by reducing DNA damage and enhancing granulosa cell proliferation via phosphatidylinositol 3-kinase pathway

We aimed to study the effects of resveratrol on the morphology, DNA fragmentation, follicular activation and cell proliferation after in vitro culture of ovine ovarian tissue, and to verify if PI3K pathway is involved in resveratrol action in the sheep ovary. Ovaries were collected and divided into fragments. One fragment was fixed for histology (fresh control). The remaining fragments were cultured for 7 days in control medium (α-MEM⁺ ) alone or with resveratrol (2, 10 or 30 µM). After culture, ovarian tissue was destined to morphological analysis. TUNEL and proliferating cell nuclear antigen (PCNA) analyses were performed in the fresh control, α-MEM⁺ and 2 µM resveratrol. Inhibition of PI3K activity was performed through pre-treatment with LY294002. The percentage of normal follicles was similar between α-MEM⁺ and 2 µM resveratrol, and higher than those in other resveratrol treatments. An increase in follicular activation was observed in all treatments compared to fresh control. DNA fragmentation decreased in tissues cultured in 2 µM resveratrol compared to α-MEM⁺ . Moreover, PCNA-positive cells were higher in 2 µM resveratrol than in α-MEM⁺ . LY294002 inhibited follicular activation stimulated by α-MEM⁺ and 2 µM resveratrol. In conclusion, 2 µM resveratrol promotes primordial follicle activation compared to the fresh control by reducing DNA fragmentation and stimulating granulosa cell proliferation through activation of the PI3K pathway.

The Growth of Preantral Follicles and the Impact of Different Supplementations and Circumstances: A Review Study with Focus on Bovine and Human Preantral Follicles

One of the most important concerns cancer survivors face is fertility. Current treatment modalities often result in damage to the reproductive system. Different options have been proposed to preserve the fertility of affected women, and many attempts have been made to improve their chance of childbearing after therapy. Cryopreservation of ovarian tissue and follicles before the onset of cancer treatment and then either transplantation of ovarian tissue or culture of ovarian tissue and individual follicles in vitro is a commonly cited approach. Extensive research is being done to design an optimal condition for the culture of ovarian follicles. Improving follicle culture systems by understanding their actual growth needs might be a crucial step toward fertility preservation in cancer patients. This review article will try to provide a summary of the role of different factors and conditions on growth of human and bovine preantral follicles in vitro.

Qilin pills alleviate oligoasthenospermia by inhibiting Bax-caspase-9 apoptosis pathway in the testes of model rats

At present, the treatment of oligoasthenospermia with western medicine is ineffective. Qilin pill (QLP) is a Chinese traditional medicine for treating male infertility. Recent multicenter clinical studies in China reported that QLPs markedly improved sperm quality. However, the mechanism of action of QLPs on oligoasthenospermia remains unknown. In this study, we investigated the mechanistic basis for improvement of semen parameters and reversal of testis damage by QLPs in a rat model of oligoasthenospermia induced by treatment with tripterygium glycosides (TGs) (40 mg/kg) once daily for 4 weeks. Rats were administered QLPs (1.62 g/kg or 3.24 g/kg) each day for 60 days, with untreated animals serving as controls. The concentration and motility of sperm extracted from rat epididymis were determined, whereas histopathological examination and immunohistochemical apoptosis analysis of rat testes was performed. Expression profiles of apoptosis-related genes were determined by microarray analysis; the results were validated by quantitative real-time PCR, western blotting, and immunohistochemistry. Sperm concentration and motility in the QLP treatment group were increased relative to those in control rats. Testis tissue and DNA damage were reversed by QLP treatment. The improvement function of QLPs on sperm and testis works mainly by suppressing mitochondrial apoptosis in the testis via modulation of B cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax), cytochrome C, caspase-9 and caspase-3 expression. QLPs could improve sperm quality and testis damage in a rat model of oligoasthenospermia by inhibiting the Bax-Caspase-9 apoptosis pathway and exerting therapeutic effects.

Role of the PI3K-Akt Signaling Pathway in the Pathogenesis of Polycystic Ovary Syndrome

This review aimed to focus on the recent progress of the understanding of the role of phosphatidylinositol 3-kinase (PI3K) in polycystic ovary syndrome (PCOS). In recent years, it has been increasingly recognized that PI3K plays an important role in PCOS whose pathogenesis is unclear. However, research continues into revealing the details of how PI3Ks are involved in developing PCOS. Previous studies have shown that activation of the PI3K-protein kinase B (Akt) signaling pathway has important effects on insulin resistance and endometrial cancer. Knowledge of the action of PI3K in PCOS might provide valuable information to further validate the pathogenesis of PCOS and suggest new methods of treatment.

Peripheral and Central Mechanisms Involved in the Hormonal Control of Male and Female Reproduction

Reproduction involves the integration of hormonal signals acting across multiple systems to generate a synchronised physiological output. A critical component of reproduction is the luteinising hormone (LH) surge, which is mediated by oestradiol (E2 ) and neuroprogesterone interacting to stimulate kisspeptin release in the rostral periventricular nucleus of the third ventricle in rats. Recent evidence indicates the involvement of both classical and membrane E2 and progesterone signalling in this pathway. A metabolite of gonadotrophin-releasing hormone (GnRH), GnRH-(1-5), has been shown to stimulate GnRH expression and secretion, and has a role in the regulation of lordosis. Additionally, gonadotrophin release-inhibitory hormone (GnIH) projects to and influences the activity of GnRH neurones in birds. Stress-induced changes in GnIH have been shown to alter breeding behaviour in birds, demonstrating another mechanism for the molecular control of reproduction. Peripherally, paracrine and autocrine actions within the gonad have been suggested as therapeutic targets for infertility in both males and females. Dysfunction of testicular prostaglandin synthesis is a possible cause of idiopathic male infertility. Indeed, local production of melatonin and corticotrophin-releasing hormone could influence spermatogenesis via immune pathways in the gonad. In females, vascular endothelial growth factor A has been implicated in an angiogenic process that mediates development of the corpus luteum and thus fertility via the Notch signalling pathway. Age-induced decreases in fertility involve ovarian kisspeptin and its regulation of ovarian sympathetic innervation. Finally, morphological changes in the arcuate nucleus of the hypothalamus influence female sexual receptivity in rats. The processes mediating these morphological changes have been shown to involve the rapid effects of E2 controlling synaptogenesis in this hypothalamic nucleus. In summary, this review highlights new research in these areas, focusing on recent findings concerning the molecular mechanisms involved in the central and peripheral hormonal control of reproduction.

Loss of vascular endothelial growth factor A (VEGFA) isoforms in granulosa cells using pDmrt-1-Cre or Amhr2-Cre reduces fertility by arresting follicular development and by reducing litter size in female mice

Because VEGFA has been implicated in follicle development, the objective of this study was to determine the effects of granulosa- and germ cell-specific VEGFA loss on ovarian morphogenesis, function, and female fertility. pDmrt1-Cre mice were mated to floxed VEGFA mice to develop granulosa-/germ cell-specific knockouts (pDmrt1-Cre;Vegfa^-/-). The time from mating to first parturition was increased when pDmrt1-Cre;Vegfa^-/- females were mated to control males (P = 0.0008) and tended to be longer for heterozygous females (P < 0.07). Litter size was reduced for pDmrt1-Cre;Vegfa^-/- females (P < 0.007). The time between the first and second parturitions was also increased for heterozygous females (P < 0.04) and tended to be increased for pDmrt1-Cre;Vegfa^-/- females (P < 0.07). pDmrt1-Cre;Vegfa^-/- females had smaller ovaries (P < 0.04), reduced plasma estradiol (P < 0.007), fewer developing follicles (P < 0.008) and tended to have fewer corpora lutea (P < 0.08). Expression of Igf1r was reduced (P < 0.05); expression of Foxo3a tended to be increased (P < 0.06); and both Fshr (P < 0.1) and Sirt6 tended to be reduced (P < 0.06) in pDmrt1-Cre;Vegfa^-/- ovaries. To compare VEGFA knockouts, we generated Amhr2-Cre;Vegfa^-/- mice that required more time from mating to first parturition (P < 0.003) with variable ovarian size. Both lines had more apoptotic granulosa cells, and vascular staining did not appear different. Taken together these data indicate that the loss of all VEGFA isoforms in granulosa/germ cells (proangiogenic and antiangiogenic) causes subfertility by arresting follicular development, resulting in reduced ovulation rate and fewer pups per litter.

The role of BH3-only proteins in apoptosis within the ovary

BH3-only proteins are pro-apoptotic members of the BCL2 family that play pivotal roles in embryonic development, tissue homeostasis and immunity by triggering cell death through the intrinsic apoptosis pathway. Recent in vitro and in vivo studies have demonstrated that BH3-only proteins are also essential mediators of apoptosis within the ovary and are responsible for the initiation of the cell death signalling cascade in a cell type and stimulus-specific fashion. This review gives a brief overview of the intrinsic apoptosis pathway and summarise the roles of individual BH3-only proteins in the promotion of apoptosis in embryonic germ cells, oocytes, follicular granulosa cells and luteal cells. The role of these proteins in activating apoptosis in response to developmental cues and cell stressors, such as exposure to chemotherapy, radiation and environmental toxicants, is described. Studies on the function of BH3-only proteins in the ovary are providing valuable insights into the regulation of oocyte number and quality, as well as ovarian endocrine function, which collectively influence the female reproductive lifespan and health.

Local VEGF inhibition prevents ovarian alterations associated with ovarian hyperstimulation syndrome

The relationship between human chorionic gonadotropin and ovarian hyperstimulation syndrome (OHSS) is partially mediated by vascular endothelial growth factor A (VEGF). The aim of this study was to investigate the effects of VEGF inhibition on the development of corpora lutea (CL) and cystic structures, steroidogenesis, apoptosis, cell proliferation, endothelial cell area, VEGF receptors (KDR and Flt-1), claudin-5 and occludin levels in ovaries from an OHSS rat model. The VEGF inhibitor used (VEGF receptor-1 (FLT-1)/Fc chimera, TRAP) decreased the concentrations of progesterone and estradiol as well as the percentage of CL and cystic structures in OHSS rats, and increased apoptosis in CL. Endothelial cell area in CL and KDR expression and its phosphorylation were increased, whereas claudin-5 and occludin levels were decreased in the OHSS compared to the control TRAP reversed these parameters. Our findings indicate that VEGF inhibition prevents the early onset of OHSS and decreases its severity in rats.

In vitro development of bovine secondary follicles in two- and three-dimensional culture systems using vascular endothelial growth factor, insulin-like growth factor-1, and growth hormone

The aim of this study was to evaluate the development and estradiol production of isolated bovine secondary follicles in two-dimensional (2D, experiment 1) and three-dimensional (3D using alginate, experiment 2) long-term culture systems in the absence (control group; only α-MEM(+)) or presence of vascular endothelial growth factor (VEGF), insulin-like growth factor-1, or GH alone, or a combination of all. A total of 363 isolated secondary follicles were cultured individually for 32 days at 38.5 °C in 5% CO2 in a humidified incubator with addition of medium (5 μL) every other day. In 2D culture system, follicular growth and antrum formation rates were higher (P < 0.05) in VEGF treatment compared with the other treatments. In 3D culture system, only estradiol concentration was greater (P < 0.05) in the GH than in the control group, whereas the other end points were similar (P > 0.05). In summary, this study demonstrated that the benefits of using a certain type of medium supplement depended on the culture system (2D vs. 3D). Vascular endothelial growth factor was an effective supplement for the in vitro culture of bovine secondary follicles when the 2D culture system was used, whereas GH only affected estradiol production using the 3D culture system. This study sheds light on advancements in methodology to facilitate subsequent studies on bovine preantral follicle development.

HIF1 activity in granulosa cells is required for FSH-regulated Vegfa expression and follicle survival in mice

Recent evidence has suggested that vascular endothelial growth factor A (VEGFA) is an important regulator of ovarian follicle development and survival. Both LH and FSH regulate Vegfa expression in granulosa cells and signal via the transcription factor hypoxia inducible factor 1 (HIF1). To further study the mechanism of action of HIF1 in the regulation of Vegfa, we studied Vegfa(delta/delta) mice, which lack a hypoxia response element in the Vegfa promoter. Granulosa cells from Vegfa(delta/delta) mice failed to respond to FSH or LH with an increase in Vegfa mRNA expression in vitro, and granulosa cells isolated from eCG-treated immature Vegfa(delta/delta) mice had significantly lower Vegfa mRNA levels compared to controls. However, normal Vegfa mRNA levels were detected in the granulosa cells from immature Vegfa(delta/delta) mice following hCG treatment. Vegfa(delta/delta) females produced infrequent litters, and their pups died shortly after birth. Ovaries from Vegfa(delta/delta) mice were much smaller than controls and contained few antral follicles and corpora lutea. Antral follicles numbers were decreased by nearly 50% in ovaries from Vegfa(delta/delta) mice relative to controls, and 74% of antral follicles in Vegfa(delta/delta) ovaries were atretic. Serum progesterone levels in adult Vegfa(delta/delta) females were significantly lower, apparently reflecting reduced numbers of corpora lutea. This study demonstrates for the first time the requirement of HIF1 for FSH-regulated Vegfa expression in vivo and that HIF1 acts via a single hypoxia response element in the Vegfa promoter to exert its regulatory functions. Our findings also further define the physiological role of VEGFA in follicle development.

Targeting angiogenesis in the pathological ovary

The ovary is a key tissue in the study of physiological neo-vascularisation in the adult and its study has highlighted important molecules involved in the regulation of angiogenesis in vivo. These include vascular endothelial growth factor, delta-like ligand 4, thrombospondin-1, prokineticin-1 and prostaglandin E2. Targeting these molecular pathways has therapeutic potential and their manipulation has an increasing preclinical and clinical role in the management of the pathological ovary. Targeting angiogenic pathways has utility in the promotion of ovarian angiogenesis to improve tissue and follicle survival and function as well as the prevention and management of ovarian hyperstimulation syndrome. There is a theoretical possibility that targeting angiogenesis may improve the function of the polycystic ovary and a real role for targeting angiogenesis in ovarian cancer.

Concanavalin-A induces granulosa cell death and inhibits FSH-mediated follicular growth and ovarian maturation in female rats

Reproductive success stems from a finely regulated balance between follicular maturation and atresia, in which the role of carbohydrate structure is poorly understood. Here, we describe for the first time a fraction of purified recombinant human FSH that is capable of bringing about the cell death of granulosa cells and preventing follicular maturation in a rat model. Further analysis by mass spectrometry revealed the presence of the lectin Concanavalin-A (Con-A) within this fraction of recombinant FSH. Using both the fractionated FSH and Con-A, the observed cell death was predominantly located to the granulosa cells. Ex vivo culture of rat follicles demonstrated that follicle degeneration occurred and resulted in the release of a denuded and deteriorated oocyte. Moreover, in vivo experiments confirmed an increase in atresia and a corresponding reduction confined to follicle in early antral stage. As a mechanism of action, Con-A reduces ovarian proliferation, Von Willebrand staining, and angiogenesis. Based on the observation that Con-A may induce granulosa cell death followed by follicle death, our results further demonstrate that follicular carbohydrate moiety is changing under the influence of FSH, which may allow a carbohydrate-binding lectin to increase granulosa cell death. The physiological consequences of circulating lectin-like molecules remain to be determined. However, our results suggest a potential exploitation of carbohydrate binding in fertility and ovarian cancer treatment. This work may shed light on a key role of carbohydrates in the still obscure physiological process of follicular selection and atresia.

Inhibition of vascular endothelial growth factor A expression in mouse granulosa cells by lentivector-mediated RNAi

Vascular endothelial growth factor (VEGF) has been found responsible for the induction of proliferation and differentiation in granulosa cells. We constructed four short hairpin RNA (shRNA) expression plasmids targeting the mouse VEGFA gene, and examined their effect on VEGF expression in mouse granulosa cells (MGC) in vitro. Four different shRNA oligonucleotides targeting the coding sequence of mouse VEGFA mRNA and one negative control (shNC) were designed and cloned into a pGPU6/GFP/Neo siRNA expression vector, and transiently transfected into MGC. At 48 h post-transfection, total RNA was extracted from the cells and subjected to qRT-PCR analysis. The most effective interference vector, shVEGF1487 was chosen for lentiviral construction. The recombinant plasmid was then transfected into 293FT cells via Lipofectamine(TM) 2000-mediated gene transfer, for the production of lentivirus, and then concentrated via ultracentrifugation. This lentiviral vector was then used for the transduction of MGC. VEGFA gene expression, apoptosis genes and VEGFA receptor genes were detected by qRT-PCR, the VEGFA protein level in culture media by ELISA assay and protein levels in MGC by Western blot analysis. The four VEGFA expression plasmids were successfully constructed and the most effective interference vector, shVEGF1487, was chosen for lentiviral production and MGC transduction. There was significant knockdown of the VEGFA gene, receptor genes and apoptosis genes for all the shVEGF constructs, compared with the shNC and Mock controls. The lentiviral vector also gave significant knockdown of the VEGFA gene. Protein levels were lower for most of the shVEGFs based on Western blot analysis with exception of VEGF1359; in this case, it was higher than shNC but lower than for the Mock group. Lentivector-transduced MGC also gave lower levels of protein. We conclude that shVEGF expression plasmids and lentivector carrying RNAi are promising tools for the inhibition of VEGF, the corresponding receptor genes, and apoptosis gene expression in MGC.

Direct survival role of vascular endothelial growth factor (VEGF) on rat ovarian follicular cells

The aim of the present work was to analyze the direct effect of VEGF in follicular cell proliferation, apoptosis and activation of the PI3K/AKT and ERK/MEK signaling pathways in early antral follicles or granulosa cells. Antral follicles or granulosa cells were isolated from prepubertal female Sprague Dawley rats treated with DES.VEGF directly stimulates follicular cell proliferation and it also decreases apoptosis by inhibiting caspase 3 activation. In addition, VEGF increases the proliferation and inhibits the apoptosis of isolated granulosa cells in culture. VEGF activates the PI3K/AKT pathway evidenced by an increase in AKT phosphorylation levels and induces the phosphorylation of ERK1/2 in cultured antral follicles. These results demonstrate for the first time that VEGF has a proliferative and cytoprotective role in early antral follicles and in granulosa cells isolated from DES treated prepubertal rats and suggest that PI3K/AKT and ERK/MEK signaling pathways are involved in these processes.

WNT4 is required for normal ovarian follicle development and female fertility

To study the role of WNT4 in the postnatal ovary, a mouse strain bearing a floxed Wnt4 allele was created and mated to the Amhr2(tm3(cre)Bhr) strain to target deletion of Wnt4 to granulosa cells. Wnt4(flox/-);Amhr2(tm3(cre)Bhr/+) mice had reduced ovary weights and produced smaller litters (P<0.05). Serial follicle counting demonstrated that Wnt4(flox/-);Amhr2(tm3(cre)Bhr/+) mice were born with a normal ovarian reserve and maintained normal numbers of small follicles until puberty but had only 25.2% of the normal number of healthy antral follicles. Some Wnt4(flox/-);Amhr2(tm3(cre)Bhr/+) mice had no antral follicles or corpora lutea and underwent premature follicle depletion. RT-PCR analyses of Wnt4(flox/-);Amhr2(tm3(cre)Bhr/+) granulosa cells and cultured granulosa cells that overexpress WNT4 demonstrated that WNT4 regulates the expression of Star, Cyp11a1, and Cyp19, steroidogenic genes previously identified as downstream targets of the WNT signaling effector CTNNB1. Decreased serum progesterone levels were found in immature, gonadotropin-treated Wnt4(flox/-);Amhr2(tm3(cre)Bhr/+) mice (P<0.05). WNT4- and CTNNB1-overexpressing cultured granulosa cells were analyzed by microarray for alterations in gene expression, which showed that WNT4 regulates additional genes involved in late follicle development via the WNT/CTNNB1 signaling pathway. Together, these data indicate that WNT4 is required for normal antral follicle development and may act by regulating granulosa cell functions including steroidogenesis.

Local effects of the sphingosine 1-phosphate on prostaglandin F2alpha-induced luteolysis in the pregnant rat

Since the regression of the corpus luteum (CL) occurs via a tightly controlled apoptotic process, studies were designed to determine if local administration of the antiapoptotic agent sphingosine 1-phosphate (S1P) effectively blocks the luteolytic action of prostaglandin F-2alpha (PGF-2alpha). On day 19 of pregnancy, 2 hr before systemic PGF-2alpha administration, rats were injected intrabursa with either S1P or vehicle (control). The activity of four caspases, which contribute to the initial (caspase-2, -8, and -9) and final (caspase-3) events in apoptosis was measured in pooled CL from four individual ovaries at 0 and 4 hr after PGF-2alpha injection. The expression of the phosphorylated form of AKT (pAKT) and tumor necrosis factor-alpha (TNF-alpha) was analyzed by ELISA. In addition, cell death was evaluated by electronic microscopy (EM) in CL 4 and 36 hr after PGF-2alpha injection. The activity of caspase-2, -3, and -8 was significantly greater by 4 hr after PGF-2alpha, but not caspase-9 activity. In contrast, expression of pAKT and TNF-alpha decreased significantly. Administration of S1P suppressed (P < 0.05) these effects, decreasing caspase activities and increasing pAKT and TNF-alpha expression. The administration of S1P also significantly decreased the percentage of luteal apoptotic cells induced by PGF-2alpha. PGF-2alpha treatment increased the prevalence of luteal cells with advanced signs of apoptosis (i.e., multiple nuclear fragments, chromatin condensation, or apoptotic bodies). S1P treatment suppressed these changes and increased the blood vessel density. These results suggest that S1P blocks the luteolytic effect of the PGF-2alpha by decreasing caspase-2, -3, and -8 activities and increasing AKT phosphorylation and TNF-alpha expression.