In brief: Accurate assessment of oocyte competence remains challenging in assisted reproduction. Artificial intelligence morphology analysis is a promising noninvasive tool. This study demonstrates that oocyte morphology scores are associated with distinct molecular signatures in follicular fluid from young oocyte donors, supporting a biological basis for computational oocyte assessment. Abstract: Oocyte quality is a key determinant of reproductive success, yet its assessment in assisted reproduction largely relies on subjective morphological criteria. Artificial intelligence-based image analysis has introduced greater objectivity into oocyte evaluation; however, the biological features captured by artificial intelligence-derived morphological scores remain incompletely defined. In this study, we integrated artificial intelligence-based oocyte morphology with molecular profiling of follicular fluid (FF) to identify biological correlates of oocyte competence. Reproductive outcomes were analysed in 49 young oocyte donors (20-33 years), while FF samples pooled per woman from a subset of 25 donors were analysed for metabolic (glucose, total cholesterol, triglycerides, high-density lipoprotein [HDL], low-density lipoprotein [LDL], apolipoprotein A1 [APOA1]), extracellular matrix-related (heparan sulfate proteoglycan 2 [HSPG2]/Perlecan), signaling-related (Gremlin-1), and fertility-related (anti-Müllerian hormone [AMH], LH, FSH) biomarkers. Artificial intelligence-derived oocyte quality scores were positively associated with specific intrafollicular markers, including glucose, total cholesterol, HDL, AMH, and HSPG2, while no associations were observed with triglycerides, LDL, Gremlin-1, LH, or FSH. APOA1 showed a positive trend with the artificial intelligence score. These findings provide a biological context for artificial intelligence-based oocyte morphological assessment by linking digital image-derived scores with metabolic and structural features of the follicular microenvironment. The integration of artificial intelligence-driven morphology with donor FF biomarker profiling may contribute to the development of more objective and biologically informed approaches for oocyte quality evaluation in assisted reproduction.

Anticancer drugs like cyclophosphamide (CTX) cause severe ovarian damage, often leading to infertility, while current fertility preservation methods are invasive and costly. This study investigates whether melatonin (MEL) can protect ovarian function in a CTX-induced premature ovarian failure (POF) mouse model, offering a potential noninvasive and cost-effective fertoprotective approach. A CTX-induced POF mouse model was used to assess MEL’s protective effects. Ovarian function was evaluated by analyzing follicle counts, ovarian weight, serum hormone levels, apoptosis markers, histopathological changes, vascular integrity, and antioxidant defences. MEL coadministration increased the proportion of primary and antral follicles (p < 0.01 and p < 0.05) while reducing atretic follicles (p < 0.05). MEL preserved ovarian weight, maintained primordial follicle counts, and prevented CTX-induced hormone level reductions. MEL also enhanced AMH-positive follicle percentage, reduced apoptosis, and mitigated vascular injury, fibrosis, and blood vessel hyalinization (p < 0.05). Furthermore, MEL restored uterine tissue architecture, improved vascular health by recruiting pericytes and smooth muscle cells (p < 0.05), and enhanced antioxidant defenses through increased expression of superoxide dismutase 1 (SOD1) (p < 0.05). MEL effectively preserves ovarian function in a CTX-induced POF model by protecting follicular development, hormonal balance, vascular integrity, and antioxidant defenses. These findings highlight MEL as a promising, noninvasive, and cost-effective strategy for fertility preservation in female cancer patients undergoing chemotherapy.

This study aimed to evaluate the long-term impact of mild COVID-19 infection and COVID-19 vaccination on ovarian function in patients undergoing assisted reproductive technology (ART). Specifically, we assessed ovarian outcomes between 9 and 18 months post-infection and investigated the effects of COVID-19 vaccines (inactivated virus and adenovirus) on reproductive parameters. The study included two objectives: (a) examining ovarian function in post-COVID-19 patients (9–18 months post-infection) compared to a control group and (b) comparing reproductive outcomes in vaccinated versus unvaccinated patients. According to the study objectives, ART patients were divided into the following groups: a control group (n = 30), a post-COVID-19 group (n = 55), an unvaccinated group (n = 70), and a vaccinated group (n = 55). Findings revealed a reduction in the number of retrieved and mature oocytes in patients over 36 years in the post-COVID-19 group. Lower IL-1β levels were found in follicular fluid (FF) of post-COVID-19 patients, while VEGF levels were reestablished between 9 and 18 months post-infection. Although cell migration was reduced in endothelial cells incubated with post-COVID-19 FF, angiogenic factor levels and DNA integrity remained stable. No significant differences in retrieved or mature oocytes were observed between vaccinated and unvaccinated patients. VEGF levels and DNA integrity in FF from post-COVID-19 patients were normalized between 9 and 18 months post-infection. Additionally, COVID-19 vaccination did not negatively impact ovarian response in ART patients, supporting vaccine safety in reproductive contexts.

AIMS:Metformin has shown beneficial effects on reproduction in women. However, its use during pregnancy remains controversial, as metformin can cross the placenta. Most studies have focused on the metabolic impact on the offspring of treated mothers, with limited information regarding its reproductive effects. The aim of this study was to evaluate potential alterations in ovarian function and fertility in female offspring of mothers treated with metformin during pregnancy and lactation. MATERIALS AND METHODS:C57BL/6 female mice were treated with metformin four weeks before mating, and the treatment was maintained during gestation and lactation. Seven weeks after weaning, metabolic parameters as well as ovarian and reproductive function of the offspring were analyzed. KEY FINDINGS:The offspring of treated mothers were lighter at birth and, in adulthood, they had more gonadal adipose tissue with no alterations in body weight. No changes in glucose metabolism were observed. Their follicular development was modified, with more early antral and atretic follicles and less primary and late antral follicles. Anti-Müllerian hormone expression and ovarian angiogenesis were increased. The estrous cycle, hormonal production and fertility were not affected by metformin exposure, however, the F2 generation showed higher body weight at birth. SIGNIFICANCE:Metformin can induce fetal programming in animals exposed to it during development, impacting metabolism and ovarian functionality in adulthood. Under physiological conditions, these alterations do not result in reduced fertility or endocrine disruptions. Our data warrant studies in women to make informed decisions regarding metformin administration during critical developmental periods in clinical settings.

Ovarian aging is associated with fibro-inflammation, contributing to the decline in oocyte count and quality. Given the immunomodulatory properties of the vasoactive intestinal peptide (VIP) in the reproductive tract, we investigated its role in maintaining ovarian immune homeostasis and preventing premature aging. We evaluated young VIP knockout (KO) mice, comparing them to young wild type (WT) females, for signs of premature aging. Histological staining revealed aberrant ovarian morphology in VIP KO mice, characterized by increased atretic follicles and decreased ovarian reserve compared to WT controls. Moreover, VIP KO ovaries showed reduced vascularization, increased collagen deposition and elevated ROS and IL-1β levels. Foamy macrophages were significantly predominant, indicating premature aging in young VIP KO ovaries. To determine potential mechanisms behind these pathogenic changes, we conditioned peritoneal macrophages from young WT or VIP KO mice in vitro with ovarian-conditioned media from young WT or VIP KO mice to mimic the respective ovarian microenvironment. When WT or VIP KO peritoneal macrophages were conditioned with ovarian media from their respective genotypes, lipid droplet accumulation increased compared to control medium. In cross-genotype experiments, WT macrophages conditioned with media from VIP KO ovaries selectively accumulated higher levels of lipid droplets, whereas no differences were observed in VIP KO macrophages conditioned with WT ovarian media. This suggests that VIP KO macrophages are uniquely sensitized to the inflammatory environment of VIP KO ovaries, implicating both ovarian factors and macrophage status. These findings highlight the role of VIP in preventing fibro-inflammation, thereby preserving ovarian health and preventing premature aging.

In brief:Formation and function of the corpus luteum strongly rely on active angiogenesis. This study demonstrates the role of the hypoxia-inducible factor (HIF) in luteinization with no effect on fertility. Abstract:HIFs are transcription factors responsible for sensing low oxygen levels and, in response, inducing the transcription of numerous genes. One of the main processes stimulated by HIFs is the formation of new vessels to increase oxygen supply to the tissue. Formation of the corpus luteum strongly depends on the vasculature, and active angiogenesis occurs during luteinization. In this study, we aimed to analyze the role of HIF in the early formation of corpus luteum and its function, and in female fertility. To this aim, we superovulated mice using equine chorionic gonadotropin and human chorionic gonadotropin (hCG) and administered the HIF inhibitor acriflavine (ACF) to the mice 3 h before hCG. We found a decrease in ovarian HIF1A and VEGFA and in the vascular area in the animals treated with ACF. Moreover, we observed an increase in aberrant structures in the ovaries and in luteal cell apoptosis. Serum progesterone levels were decreased together with ovarian STAR expression. However, the animals treated with ACF during the early formation of the corpus luteum were completely fertile and no alterations were observed when the treated females were mated with fertile males. These results collectively suggest that HIF regulates gonadotropin-induced corpus luteum formation by acting on luteal blood vessel formation, luteal cell survival and progesterone synthesis. However, adequate HIF activity may not be essential to achieve and maintain pregnancy. These findings are significant to better understand the complex mechanisms of corpus luteum formation and identify potential abnormalities to allow better knowledge of ovarian physiology and pathologies in which this factor could be involved.

In brief:The hypoglycemic drug metformin has shown reproductive effects in women, although its mechanism of action is not fully understood. In this study, we demonstrate the direct effects of metformin on the ovary of healthy mice, with no alterations in fertility. Abstract:Metformin is a hypoglycemic drug widely used in type-2 diabetes (T2D) patients. In recent years, this drug has been suggested as a treatment for gestational diabetes and recommended to women with ovarian hyperstimulation syndrome (PCOS) to increase the chances of pregnancy or avoid early miscarriages. However, the exact effects of metformin on the female reproductive tract in general, and on the ovary in particular, are still not completely understood. In this study, we analyzed the effect of metformin on fertility and ovarian physiology in healthy female mice. We found that this drug altered the estrous cycle, early follicular development, serum estradiol and progesterone levels, and ovarian steroidogenic enzyme expression. Moreover, ovarian angiogenesis was lower in metformin-treated animals compared with untreated ones, whereas natural or gonadotropin-induced fertilization rates remained unchanged. However, offspring of metformin-treated animals displayed decreased body weight at birth. In this work, we unraveled the main effects of metformin on the ovary, isolated from other conditions such as hyperglycemia and hyperandrogenism, which is essential for a better understanding of metformin's mechanisms of action on reproduction and fertility.

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 GABA A receptor increased after ALLO treatment. To evaluate if the ovarian GABA A 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 GABA A receptor. Intrabursal ALLO administration alters several processes of the ovarian morpho-physiology of the female rat, related to fertility and oocyte quality.

Abstract Ovarian aging is associated with inflammation, contributing to the decline in oocyte count and quality. Since the vasoactive intestinal peptide (VIP) is an immunopeptide found in the reproductive tract with anti inflammatory effects inducing a tolerogenic response, we focus on VIP contribution to ovarian immune homeostasis preventing premature aging. We observed that young VIP KO mice (3 months old) display an altered ovarian histology with an increase in atretic follicles and less mature follicles as in aged WT mice (8 months old). This microenvironment was accompanied by an increased fibrosis deposition, ROS and IL-1β production. Interestingly, we found a significant decrease in ovarian reserve and the presence of foamy macrophages in young VIP KO ovary associated with premature aging. Getting insight into the mechanism involved in foam cell generation, we pre-conditioned young WT or VIP KO macrophages with WT or VIP KO ovarian media for 48h to mimic the ovarian microenvironment. Macrophages from VIP KO mice display a differential phagocytic ability of apoptotic bodies after preconditioning with WT or VIP KO ovarian media. However, only in VIP KO macrophages conditioned with VIP KO ovarian media we found an increase in lipid droplet accumulation, consistent with the formation of foamy macrophages. These findings highlight the role of VIP in regulating ovarian immune microenvironment, thereby preserving ovarian health and preventing premature aging.

Complex immune regulation during pregnancy is required to ensure a successful pregnancy outcome. Vasoactive intestinal peptide (VIP) has local immunoregulatory effects on the ovary, uterus and maternal-fetal interface that favor a tolerogenic maternal microenvironment. Since the VIP Knockout (KO) mice are subfertile, we investigated the mechanisms underlying the effects of VIP deficiency on ovarian physiology and immune homeostasis. Therefore, we studied VIP KO, deficient (HT) and wild type (WT) female mice in estrus at 3 or 8 months of age. Young KO mice showed abnormal cycle timing and regularity associated with dysfunctional ovaries. Ovaries presented higher number of atretic follicles and reduced number of corpora lutea leading to a lower ovulation rates. Part of the VIP KO mice (25 %) failed to ovulate or ovulated oocytes incompetent to be fertilized (50 %). In particular, ovaries of young KO mice exhibited features of premature aging accompanied by a pro-inflammatory milieu with increased levels of IL-1β. A unique macrophage subpopulation identified as "foamy macrophages" was found. On the other hand, aged VIP KO females did not gain body weight probably due to the sustained production of E2. Finally, the adoptive transfer of FOXP3+ cells to infertile VIP KO females resulted in their selective recruitment to the ovary. It increased FOXP3/RORγt and TGFβ/IL-6 ratio improving ovarian microenvironment and pregnancy rate. The present results suggest that VIP contributes to ovarian homeostatic mechanisms required for a successful pregnancy.

Introduction: The mechanisms that govern fibroblast behavior during the vascular adaptations of the uterus at early pregnancy remain unknown. Anandamide, an endocannabinoid, binds to cannabinoid receptors (CBs), and regulates gestation and angiogenesis. Its tone is regulated by fatty acid amide hydrolase (FAAH) within the uterus. We investigated the role of anandamide in endometrial fibroblasts migration and whether anandamide modulates fibroblasts-endothelial crosstalk.Methods: T-hESC and EA.hy926 cell lines were used as models of endometrial stromal and endothelial cells, respectively. T-hESC were incubated with anandamide plus different agents. Migration was tested (wound healing assay and phalloidin staining). Protein expression and localization were studied by Western blot and immunofluorescence. To test fibroblast-endothelial crosstalk, EA.hy926 cells were incubated with fibroblast conditioned media obtained after T-hESC migration.Results: Anandamide 1 nM increased T-hESC migration via CB1 and CB2. Cyclooxygenase-2 participated in anandamide-stimulated fibroblast migration. Prostaglandin F2alpha, and not prostaglandin E2, increased fibroblast wound closure. CB1, CB2, cyclooxygenase-2 and FAAH were expressed in T-hESC. Anandamide did not alter cyclooxygenase-2 localization but induced its cytoplasmic and nuclear expression through CB1 and CB2. URB-597, a FAAH selective inhibitor, also increased T-hESC migration via both CBs, and augmented cyclooxygenase-2 expression. Conditioned media from anandamide-induced T-hESC wound healing closure stimulated endothelial migration and did not alter their proliferation. Soluble factors from cyclooxygenase-2 were secreted by T-hESC and participated in T-hESC-induced EA.hy926 migration. Although anandamide-conditioned media augmented in EA.hy926 the expression of & gamma;H2AX, a marker of DNA damage, cyclooxygenase-2 was not involved in this effect.Discussion: Our results provide novel evidence about an active role of anandamide on endometrial fibroblast behavior as a mechanism regulating uterine vascular adaptations in early gestation.

While oocytes and embryos cryopreservation can favor some patients with cancer-induced infertility to achieve pregnancy, the development of effective therapeutic strategies to preserve ovarian function during chemotherapy would be a significant advantage. The aim of the present study is to analyze whether Resveratrol treatment (Res) can preserve ovarian function from doxorubicin (Doxo)-induced gonadotoxicity using a mice model of premature ovarian failure. Res (7 and 15 mg/kg) increased the percentage of primary and antral follicles whilst decreasing the percentage of atretic follicles compared to Doxo alone. Res preserved the number of primordial follicles compared with those in the Doxo group but they did not change from those in the control group. Res treatment increased the number of AMH positive follicles compared to Doxo alone. Res increased proliferation index in follicular cells and reduced the DNA damage and apoptosis in preantral and early antral follicles compared to Doxo alone. Additionally, Doxo administration caused a severe endothelial damage and affected microvasculature stability in the ovary. However, Res was able to increase the recruitment of pericytes and smooth muscle cells in the Doxo-treated group. We also found that Res increased the expression of VEGF compared to Doxo alone. By H&E staining, Doxo-treated mice demonstrated endometrial alterations compared to controls, affecting both epithelial and stromal compartments. Nonetheless, Res restored the architecture of uterine tissue. Moreover, we also showed that Res administration is able to maintain antioxidant defenses through the increase of SOD expression in the Doxo-induced POF model. In conclusion, Res administration prior to and during Doxo treatment might serve as a noninvasive and low-cost protocol to preserve ovarian function in female cancer survivors.

Female fertility is highly dependent on energy balance. High fat diet (HFD) intake entails a risk of infertility and ovulatory disorders. Considering the increase in the prevalence of overweight and obesity over the last decades, it is crucial to understand the mechanisms involved in overweight-associated infertility. In this study, we evaluated the reproductive performance of female mice fed with a HFD and the effects of metformin administration on ovarian function in these mice. We hypothesized that one of the mechanisms involved in subfertility due to a HFD intake is the alteration of ovarian blood vessel formation. We found that mice fed with HFD had altered estrous cycles and steroidogenesis, increased ovarian fibrosis, fewer pups per litter and require more time to achieve pregnancy. HFD-fed mice also presented dysregulated ovarian angiogenesis and an increase in nuclear DNA damage in ovarian cells. Ovulation rates were lower in these animals, as evidenced both in natural mating and after ovulation induction with gonadotropins. Metformin ameliorated ovarian angiogenesis, improved steroidogenesis, fibrosis, and ovulation, decreased the time to pregnancy and increased litter sizes in HFD-fed mice. We conclude that ovarian angiogenesis is one of the mechanisms detrimentally affected by HFD intake. Since metformin could improve ovarian microvasculature, it may be an interesting strategy to study in women to shed light on new targets for patients with metabolic disturbances.

Context The FMR1 gene consists of 17 exons and codes for the FMRP protein. FMR1 is involved in four genetic disorders depending on the CGG repeats length in its 5′UTR: the full mutation is responsible for the Fragile X syndrome while the premutation is associated with the Fragile X-associated Tremor/Ataxia Syndrome, Fragile X-associated Primary Ovarian Insufficiency (FXPOI) and Fragile X-associated neuropsychiatric disorders. FMR1 presents multiple isoforms resulting from skipping of exons 12 and 14 and the use of alternative splice sites in exons 15 and 17. Aims To investigate the expression of Fmr1 splicing variants during folliculogenesis in the rat. Methods We used preantral, early antral and preovulatory follicles to isolate RNA and characterise, by fluorescent PCR followed by sequencing, all the isoforms present in the different follicular stages. Key results We identified two isoforms resulting from splicing of exon 12, six isoforms resulting from splicing of exon 14 and 15 and one isoform for exon 17. Conclusions The expression levels of the isoforms vary within each follicular stage but not between different stages of folliculogenesis. Importantly, we identify for the first time in rat, an isoform that contains exon 12 and two isoforms, one that includes and one that excludes exon 14 and use the third acceptor site in exon 15. Implications Characterisation of the different FMR1 variants expressed during folliculogenesis will help to understand the potential distinct cellular roles of each of them and the possible implication in the development of FXPOI.

CONTEXT:The FMR1 gene consists of 17 exons and codes for the FMRP protein. FMR1 is involved in four genetic disorders depending on the CGG repeats length in its 5'UTR: the full mutation is responsible for the Fragile X syndrome while the premutation is associated with the Fragile X-associated Tremor/Ataxia Syndrome, Fragile X-associated Primary Ovarian Insufficiency (FXPOI) and Fragile X-associated neuropsychiatric disorders. FMR1 presents multiple isoforms resulting from skipping of exons 12 and 14 and the use of alternative splice sites in exons 15 and 17.AIMS:To investigate the expression of Fmr1 splicing variants during folliculogenesis in the rat.METHODS:We used preantral, early antral and preovulatory follicles to isolate RNA and characterise, by fluorescent PCR followed by sequencing, all the isoforms present in the different follicular stages.KEY RESULTS:We identified two isoforms resulting from splicing of exon 12, six isoforms resulting from splicing of exon 14 and 15 and one isoform for exon 17.CONCLUSIONS:The expression levels of the isoforms vary within each follicular stage but not between different stages of folliculogenesis. Importantly, we identify for the first time in rat, an isoform that contains exon 12 and two isoforms, one that includes and one that excludes exon 14 and use the third acceptor site in exon 15.IMPLICATIONS:Characterisation of the different FMR1 variants expressed during folliculogenesis will help to understand the potential distinct cellular roles of each of them and the possible implication in the development of FXPOI.

Several organs, such as the heart, breasts, intestine, testes, and ovaries, have been reported to be target tissues of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. To date, no studies have demonstrated SARS-CoV-2 infection in the female reproductive system. In the present study, we investigated the effects of SARS-CoV-2 infection on ovarian function by comparing follicular fluid (FF) from control and recovered coronavirus disease 2019 (COVID-19) patients and by evaluating the influence of these FF on human endothelial and non-luteinized granulosa cell cultures. Our results showed that most FFs (91.3%) from screened post COVID-19 patients were positive for IgG antibodies against SARS-CoV-2. Additionally, patients with higher levels of IgG against SARS-CoV-2 had lower numbers of retrieved oocytes. While VEGF and IL-1β were significantly lower in post COVID-19 FF, IL-10 did not differ from that in control FF. Moreover, in COV434 cells stimulated with FF from post COVID-19 patients, steroidogenic acute regulatory protein (StAR), estrogen-receptor β (Erβ), and vascular endothelial growth factor (VEGF) expression were significantly decreased, whereas estrogen-receptor α (ERα) and 3β-hydroxysteroid dehydrogenase (3β-HSD) did not change. In endothelial cells stimulated with post COVID-19 FF, we observed a decrease in cell migration without changes in protein expression of certain angiogenic factors. Both cell types showed a significantly higher γH2AX expression when exposed to post COVID-19 FF. In conclusion, our results describe for the first time that the SARS-CoV-2 infection adversely affects the follicular microenvironment, thus dysregulating ovarian function.

The aim of the present study is to assess whether low level laser therapy (LLLT) can protect ovaries from chemotherapy-induced gonadotoxicity using a mice model of premature ovarian failure induced by cyclophosphamide (CTX). LLLT (64 J/cm2) increased the number of antral follicles whilst decreasing the number of atretic follicles compared to CTX alone. LLLT increased the number of primordial follicles compared with those in the CTX group but they did not differ from those in the control group. LLLT treatment increased the number of AMH-positive follicles compared to CTX alone. LLLT application increased ovarian weight, serum progesterone concentration and P450scc protein levels compared to CTX alone. LLLT reduced the apoptosis in antral follicles and the BAX/BCL-2 ratio compared to CTX alone. Vascular morphology, analysed by CD31 and α-SMA immunostaining, was restored in LLLT-treated ovaries compared to CTX alone. In conclusion, application of LLLT prior to CTX might serve as a promising and novel protocol to preserve female fertility in cancer survivors.

Although advances in the prediction and management of ovarian hyperstimulation syndrome (OHSS) have been introduced, complete prevention is not yet possible. Previously, we and other authors have shown that vascular endothelial growth factor, angiopoietins (ANGPTs) and sphingosine-1-phosphate are involved in OHSS etiology. In addition, we have demonstrated that ovarian protein levels of platelet-derived growth factor (PDGF) ligands-B and-D decrease in an OHSS rat model, whilst PDGFR-beta and ANGPT2 remain unchanged. In the present work, we investigated the role of PDGF-B in OHSS by evaluating ligand protein levels in follicular fluid (FF) from women at risk of developing OHSS and by using an immature rat model of OHSS. We demonstrated that PDGF-B and PDGF-D are lower in FF from women at risk of developing OHSS compared to control patients (P<0.05). In the OHSS rat model, PDGF-B (0.5 mu g/ovary) administration decreased ovarian weight (P<0.05), reduced serum progesterone (P<0.05) and lowered the percentage of cysts (P<0.05), compared to untreated OHSS rats, but had no effect on the proportion of follicles or corpora lutea (CL). PDGF-B treatment also restored the expression of steroidogenic acute regulatory protein (P<0.05) and P450 cholesterol side-chain cleavage enzyme (P<0.01) to control levels. In addition, PDGF-B increased the peri-endothelial cell area in CL and cystic structures, and reduced vascular permeability compared to untreated OHSS ovaries. Lastly, PDGF-B increased the levels of junction proteins claudin-5 (P<0.05), occludin (P<0.05) and beta-catenin (P<0.05), while boosting the extracellular deposition of collagen IV surrounding the ovarian vasculature (PP<0.01), compared to OHSS alone. In conclusion, our findings indicate that PDGF-B could be another crucial mediator in the onset and development of OHSS, which may lead to the development of novel prediction markers and therapeutic strategies.

The aim of this study was to investigate whether the Notch pathway is modulated in response to the downregulation of the Wnt/Β-catenin system in corpora lutea (CLs) from superovulated rats. To this end, we analyzed the effect of in vitro CL Wnt/Β-catenin inhibition on the expression of Notch members and on luteal function. Mechanically isolated rat CLs were cultured with ICG-001, a Wnt/B-catenin inhibitor. In this system, Wnt/B-catenin inhibition reduced progesterone production and decreased StAR protein levels. Besides, Wnt/B-catenin inhibition stimulated the Notch system, evidenced by an increase in Hes1 expression, and promoted the expression of selected Notch family members. At long incubation times, StAR levels and progesterone concentration reached the control values, effects probably mediated by the Notch pathway. These results provide the first evidence of a compensatory mechanism between Wnt/B-catenin signaling and the Notch system, which contributes to the homeostasis of luteal cells.