Affect Oocyte Maturation Research Articles

Antimony exposure affects oocyte quality and early embryo development via excessive mitochondrial oxidation and dysfunction

Antimony (Sb) is a metalloid, widely presents in the environment and associates with human health. In this study, we aimed to decipher whether Sb exposure is harmful to female reproduction and explore the underlying mechanisms. The ICR mice were exposed to 0, 5, 10, and 20 mg/kg acetate potassium Sb tartrate trihydrate by intraperitoneal injection for 10 days, then mouse oocytes were collected for further analysis. We first found a significant decrease in the proportion of MII-stage oocytes obtained from supernumerary ovulation in the fallopian tubes and early embryo development under Sb treatment. Then a series of tests showed Sb affects oocyte maturation by damaging the cytoskeleton of microtubule and actin. Moreover, the abnormal distribution of cortical granules and their component Ovastacin in oocytes, combined with reduced expression levels of Juno, affected sperm-oocyte binding and led to fertilization failure. Based on the sequencing results and experimental validation, it was demonstrated that Sb exposure impairs mitochondrial distribution and membrane potential, elevated levels of mitochondrial superoxide, finally caused energy supply deficits. Mitochondrial damage in oocytes after Sb exposure results in the excessive oxidative stress and early apoptosis. Taken together, these data suggest that Sb exposure decreases oocyte quality and female fertilization ability by impairing mitochondrial function and redox perturbation.

Impact of Amphiregulin on Oocyte Maturation and Embryo Quality: Insights from Clinical and Molecular Perspectives

AbstractIdentifying non-invasive biomarkers which can predict the outcome of intracytoplasmic sperm injection (ICSI) is crucial, particularly in Germany where the challenges are intensified by the Embryo Protection Act. Recent research has highlighted biomarkers within the epidermal growth factor (EGF) family as central to follicular processes, although their predictive utility remains a subject of debate in the literature. Therefore, the primary objective of this study was to investigate the significance of amphiregulin concentrations in follicular fluid and gene expression in mural granulosa cells on oocyte maturation, fertilization, and embryo quality.A total of 33 women were recruited at the University Clinic of Saarland Fertility Center (Homburg, Germany). Follicular fluid aspiration consisted of single/individual aspiration of follicles, enabling a 1 : 1 correlation with retrieved oocytes. Follicular fluid and mural granulosa cell samples from 108 oocytes were analyzed. Amphiregulin levels were determined with enzyme-linked immunosorbent assay, while gene expression was analyzed with the StepOnePlus Real-Time PCR System using TaqMan Fast Advanced Master Mix assays.Results showed that amphiregulin concentrations affect oocyte maturation, fertilization, and embryo quality, while luteinizing hormone concentrations influence oocyte maturation, with significant differences identified between fertilized/unfertilized and good/poor embryo groups. Amphiregulin expression significantly impacts oocyte maturation, with downregulation observed in immature oocytes, while luteinizing hormone/chorionic gonadotropin receptor expression showed no significant differences between groups and did not influence maturation, fertilization, or embryo quality.These findings are very important for advancing infertility treatment, especially in Germany. The results for amphiregulin may provide prognostic insights which could be useful when selecting viable oocytes and embryos. This research underscores the importance of non-invasive biomarkers for optimizing ICSI outcomes and potentially enhancing the success rates of assisted reproductive technology.

Proteome and metabolomic profile of Mongolian horse follicular fluid during follicle development

During follicular development, changes in the composition of the follicular fluid are synchronized with the development of oocytes. Our aim was to screen the key factors affecting oocyte maturation and optimize the in vitro culture protocol by understanding the changes of proteins and metabolites in follicular fluid. Follicles are divided into three groups according to their diameter (small follicle fluid (SFF): 10 mm < d < 20 mm; medium follicle fluid (MFF): 20 mm < d < 30 mm; large follicle fluid (LFF): 30 mm < d). Proteins and metabolites from the follicular fluid were analyzed by mass spectrometry. The results showed that: in LFF vs MFF, 20 differential abundant protein (DAP) and 88 differential abundant metabolites (DAM) were screened out; In SFF vs MFF, 3 DAPs and 65 DAMs were screened out; In MFF vs SFF, 24 DAPs and 35 DAMs were screened out. The analysis of differential proteins and metabolites showed that glycerophosphate hydrolysis decreased during follicular development, and proteins played a major role in metabolism and binding. In addition, DAMs and DAPs are co-enriched in the “linoleic acid metabolism” pathway. Combinatorial analysis reveals the dynamic profile of follicular fluid during follicular development and provides fundation for further exploring the function of follicular fluid in Mongolian horse.

PrG protects postovulatory oocytes aging in mice through the putrescine pathway

Postovulatory aging of oocytes involves a series of deleterious molecular and cellular changes, which adversely affect oocyte maturation, fertilization, and early embryonic development. Petunidin-3-O-(6-O-pcoumaroyl)-rutinoside-5-O-glucoside (PrG), the main active ingredient of anthocyanin, exerts antioxidant effects. This study investigated whether PrG supplementation could delay postovulatory oocyte aging by alleviating oxidative stress. Our results showed that PrG supplementation decreased the number of abnormal morphology oocytes and improved the oxidative stress of aged oocytes by facilitating the reduction of the reactive oxygen species, the increase in glutathione content, and the recovery of expression of antioxidant-related gene expression. In addition, PrG treatment recovered mitochondrial dysfunction, including mitochondrial distribution, mitochondrial membrane potential and adenosine triphosphate in aged oocytes. PrG-treated oocytes returned to normal levels of cytoplasmic and mitochondrial calcium. Notably, PrG inhibited early apoptosis in aged oocytes. RNA-seq and qRT-PCR results revealed that PrG ameliorated oxidative stress injury in postovulatory aging oocytes of mice via the putrescine pathway. In conclusion, in vitro PrG supplementation is a potential therapy for delaying postovulatory oocyte aging.

Transcriptome analysis of porcine oocytes during postovulatory aging

Decreased oocyte quality is a significant contributor to the decline in female fertility that accompanies aging in mammals. Oocytes rely on mRNA stores to support their survival and integrity during the protracted period of transcriptional dormancy as they await ovulation. However, the changes in mRNA levels and interactions that occur during porcine oocyte maturation and aging remain unclear. In this study, the mRNA expression profiles of porcine oocytes during the GV, MII, and aging (24 h after the MII stage) stages were explored by transcriptome sequencing to identify the key genes and pathways that affect oocyte maturation and postovulatory aging. The results showed that 10,929 genes were coexpressed in porcine oocytes during the GV stage, MII stage, and aging stage. In addition, 3037 genes were expressed only in the GV stage, 535 genes were expressed only in the MII stage, and 120 genes were expressed only in the aging stage. The correlation index between the GV and MII stages (0.535) was markedly lower than that between the MII and aging stages (0.942). A total of 3237 genes, which included 1408 upregulated and 1829 downregulated genes, were differentially expressed during porcine oocyte postovulatory aging (aging stage vs. MII stage). Key functional genes, including ATP2A1, ATP2A3, ATP2B2, NDUFS1, NDUFA2, NDUFAF3, SREBF1, CYP11A1, CYP3A29, GPx4, CCP110, STMN1, SPC25, Sirt2, SYCP3, Fascin1/2, PFN1, Cofilin, Tmod3, FLNA, LRKK2, CHEK1/2, DDB1/2, DDIT4L, and TONSL, and key molecular pathways, such as the calcium signaling pathway, MAPK signaling pathway, TGF-β signaling pathway, PI3K/Akt signaling pathway, FoxO signaling pathway, gap junctions, and thermogenesis, were found in abundance during porcine postovulatory aging. These genes are mainly involved in the regulation of many biological processes, such as oxidative stress, calcium homeostasis, mitochondrial function, and lipid peroxidation, during porcine oocyte postovulatory aging. These results contribute to a more in-depth understanding of the biological changes, key regulatory genes and related biological pathways that are involved in oocyte aging and provide a theoretical basis for improving the efficiency of porcine embryo production in vitro and in vivo.

Effects of MEK1/2 inhibitor U0126 on FGF10-enhanced buffalo oocyte maturation in vitro

Fibroblast growth factor 10 (FGF10) plays critical roles in oocyte maturation and embryonic development; however, the specific pathway by which FGF10 promotes in vitro maturation of buffalo oocytes remains elusive. The present study was aimed at investigating the mechanism underlying effects of the FGF10-mediated extracellular regulated protein kinases (ERK) pathway on oocyte maturation and embryonic development in vitro. MEK1/2 (mitogen-activated protein kinase kinase) inhibitor U0126, alone or in combination with FGF10, was added to the maturation culture medium during maturation of the cumulus oocyte complex. Morphological observations, orcein staining, apoptosis detection, and quantitative real-time PCR were performed to evaluate oocyte maturation, embryonic development, and gene expression. U0126 affected oocyte maturation and embryonic development in vitro by substantially reducing the nuclear maturation of oocytes and expansion of the cumulus while increasing the apoptosis of cumulus cells. However, it did not have a considerable effect on glucose metabolism. These findings suggest that blocking the MEK/ERK pathway is detrimental to the maturation and embryonic development potential of buffalo oocytes. Overall, FGF10 may regulate the nuclear maturation of oocytes and cumulus cell expansion and apoptosis but not glucose metabolism through the MEK/ERK pathway. Our findings indicate that FGF10 regulates resumption of meiosis and expansion and survival of cumulus cells via MEK/ERK signaling during in vitro maturation of buffalo cumulus oocyte complexes. Elucidation of the mechanism of action of FGF10 and insights into oocyte maturation should advance buffalo breeding. Further studies should examine whether enhancement of MEK/ERK signaling improves embryonic development in buffalo.

3-Methyl-4-nitrophenol Exposure Deteriorates Oocyte Maturation by Inducing Spindle Instability and Mitochondrial Dysfunction.

3-methyl-4-nitrophenol (PNMC), a well-known constituent of diesel exhaust particles and degradation products of insecticide fenitrothion, is a widely distributed environmental contaminant. PNMC is toxic to the female reproductive system; however, how it affects meiosis progression in oocytes is unknown. In this study, in vitro maturation of mouse oocytes was applied to investigate the deleterious effects of PNMC. We found that exposure to PNMC significantly compromised oocyte maturation. PNMC disturbed the spindle stability; specifically, it decreased the spindle density and increased the spindle length. The weakened spindle pole location of microtubule-severing enzyme Fignl1 may result in a defective spindle apparatus in PNMC-exposed oocytes. PNMC exposure induced significant mitochondrial dysfunction, including mitochondria distribution, ATP production, mitochondrial membrane potential, and ROS accumulation. The mRNA levels of the mitochondria-related genes were also significantly impaired. Finally, the above-mentioned alterations triggered early apoptosis in the oocytes. In conclusion, PNMC exposure affected oocyte maturation and quality through the regulation of spindle stability and mitochondrial function.

Pretreatment with oral contraceptive pills in women with PCOS scheduled for IVF: a randomized clinical trial

Abstract STUDY QUESTION What is the effect of pretreatment with oral contraceptive pills (OCPs) on oocyte and embryo quality and pregnancy rates in women with polycystic ovary syndrome (PCOS) scheduled for IVF/ICSI cycles? SUMMARY ANSWER In women with PCOS who underwent a first or second IVF/ICSI cycle with a GnRH antagonist protocol and were randomized to start ovarian stimulation immediately, the quality of cleavage-stage embryos was non-inferior to pretreatment with OCP. WHAT IS KNOWN ALREADY PCOS in Asian populations is characterized by high levels of circulating LH in the early follicular phase. Previous studies indicated that inappropriately high LH levels might affect oocyte maturation and fertilization rates, and impaired embryo quality, consequently resulting in higher rates of impaired pregnancy and miscarriage in women with PCOS. OCPs are frequently used as pretreatment to lower LH levels in PCOS patients. STUDY DESIGN, SIZE, DURATION We performed a randomized controlled trial. After informed consent, women diagnosed with PCOS scheduled for their first or second IVF/ICSI cycle with a GnRH antagonist protocol were randomized to receive OCPs (OCP group) or start ovarian stimulation immediately, regardless of the day of the menstrual cycle (non-OCP group). Using a non-inferiority hypothesis, the sample size was calculated at 242 women. The study lasted from 7 February 2018 to 31 August 2021. PARTICIPANTS/MATERIALS, SETTING, METHODS A total of 242 infertility patients with PCOS undergoing the first or second cycle of IVF or ICSI were enrolled and randomized into two groups. In the OCP group, recombinant FSH was started on Day 7 of the washout period after pretreatment with OCP. In the non-OCP group, recombinant FSH was started immediately regardless of the day of the menstrual cycle. All participants received standardized GnRH antagonist ovarian stimulation. The freeze-all strategy was applied to all participants. The primary outcome was the number of good-quality embryos on Day 3 after insemination. Secondary outcomes included the rates of blastocyst formation, implantation, clinical pregnancy, and live birth from the first frozen/warmed embryo transfer cycles and cumulative live birth rates. MAIN RESULTS AND THE ROLE OF CHANCE We randomized 242 women to receive OCP (n = 121) or start immediately with ovarian stimulation (n = 121). The number of good-quality embryos on Day 3 in the OCP group was non-inferior to the non-OCP group (OCP group versus non-OCP group, 6.58 ± 4.93 versus 7.18 ± 4.39, AD −0.61, 95% CI: −1.86 to 0.65, P = 0.34). The rates of blastocyst formation (55.4% versus 52.9%, relative risk (RR) 1.11, 95% CI: 0.96 to 1.28, P = 0.17), implantation (63.0% versus 65.5%, RR 0.90, 95% CI: 0.53 to 1.53, P = 0.79), clinical pregnancy (67.9% versus 68.8%, RR 0.96, 95% CI: 0.54 to 1.71, P = 1.0), and live birth rate (52.8% versus 55.1%, RR 0.92, 95% CI: 0.53 to 1.56, P = 0.79) of the first frozen/warmed embryo transfer cycles were all comparable between the OCP and non-OCP group, respectively. Cumulative live birth rates were also similar in the OCP and non-OCP groups (78.3% versus 83.5%, respectively RR 0.71, 95% CI: 0.36 to 1.42, P = 0.39). LIMITATIONS, REASONS FOR CAUTION Only patients with PCOS in Southern China were recruited. Therefore, caution is necessary when generalizing our results to all such patients with PCOS. Also, since a freeze-only strategy was used, the results of this study are only applicable when infertile women with PCOS undergo the freeze-only method. The obvious treatment difference between the two groups meant that the study was designed as an open-label study for women and doctors. The study had a randomized controlled design that minimized bias. WIDER IMPLICATIONS OF THE FINDINGS Pretreatment with OCPs to lower LH levels in patients with PCOS before ovarian stimulation in IVF or ICSI cycles may not improve the quality of cleavage-stage embryos. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by the National Key Research and Development Program of China (No. 2023YFC2705503). This study was supported in part by the Investigator-Initiated Studies Program (grant from MSD and Organon). BWM reports consultancy, travel support, and research funding from Merck. He reports consultancy from Organon and Norgine, and also reports holding stock from ObsEva. No conflicts of interest are declared for the other authors. TRIAL REGISTRATION NUMBER Chinese Clinical Trial Registry (No. chiCTR1800014822). URL: https://www.chictr.org.cn/showproj.html?proj=25280 TRIAL REGISTRATION DATE 7 February 2018. DATE OF FIRST PATIENT’S ENROLLMENT 22 February 2018.

Effects of Leonurine on oocyte maturation and parthenogenetic embryo development in sheep.

Leonurine (LEO), an alkaloid isolated from Leonurus spp., has anti-oxidant, anti-inflammatory and anti-apoptotic effects and can prevent damage caused by reactive oxygen species (ROS). These properties suggest that it can improve the maturation rate of oocytes and developmental ability of embryos, which are key parameters in animal breeding. In this study, the effects of LEO on invitro maturation and early embryonic development in sheep oocytes were evaluated. Among various doses examined (0, 10, 20 and 40 μM), a dose of 20 μM was optimal with respect to the oocyte maturation rate. Compared with estimates in the control group, GSH levels and mitochondrial membrane potential of sheep oocytes treated with 20 μM LEO were significantly higher, and 40 μM LEO would affect oocyte maturation. Additionally, ROS levels were significantly lower, expression levels of the antioxidant genes CAT and SOD1 were significantly higher, and there was no significant difference in GPX3 expression. The Bax/Bcl-2 ratio and Caspase-3 expression were significantly reduced in the 20 μM LEO group. During early embryonic development invitro, the cleavage rate and blastocyst rate were significantly higher in the 20 μM LEO treatment group compared to other groups. GSH levels and mitochondrial membrane potential were significantly higher, while ROS levels were significantly lower, and expression levels of the antioxidant genes CAT, GPX3 and SOD1 were significantly higher in eight-cell embryos treated with 20 μM LEO than in the control group. The Bax/Bcl-2 ratio and Caspase-3 levels were significantly decreased. In summary, LEO can reduce the effect of oxidative stress, improve the oocyte maturation rate and enhance embryonic development.

Nano-graphene oxide particles induce inheritable anomalies through altered gene expressions involved in oocyte maturation

The inheritable impact of exposure to graphene oxide nanoparticles (GO NPs) on vertebrate germline during critical windows of gamete development remain undetermined to date. Here, we analyzed the transgenerational effects of exposure to nano-graphene oxide particles (nGO) synthesized in house with lateral dimensions 300–600 nm and surface charge of −36.8 mV on different developmental stages of germ cells (GCs): (1) during GCs undergoing early development and differentiation, and (2) during GCs undergoing gametogenesis and maturation in adulthood. Biocompatibility analyses in Japanese medaka embryos showed lethality above 1 µg/ml and also an aberrant increase in germ cell count of both males and females at doses below the lethal dose. However, no lethality or anomalies were evident in adults up to 45 µg/ml. Long term exposure of embryos and adults for 21 days resulted in reduced fecundity. This effect was transmitted to subsequent generations, F1 and F2. Importantly, the inheritable effects of nGO in adults were pronounced at a high dose of 10 µg/ml, while 1 µg/ml showed no impact on the germline indicating lower doses used in this study to be safe. Further, expressions of selected genes that adversely affected oocyte maturation were enhanced in F1 and F2 individuals. Interestingly, the inheritance patterns differed corresponding to the stage at which the fish received the exposure.

Calcium signaling in oocyte quality and functionality and its application.

Calcium (Ca2+) is a second messenger for many signal pathways, and changes in intracellular Ca2+ concentration ([Ca2+]i) are an important signaling mechanism in the oocyte maturation, activation, fertilization, function regulation of granulosa and cumulus cells and offspring development. Ca2+ oscillations occur during oocyte maturation and fertilization, which are maintained by Ca2+ stores and extracellular Ca2+ ([Ca2+]e). Abnormalities in Ca2+ signaling can affect the release of the first polar body, the first meiotic division, and chromosome and spindle morphology. Well-studied aspects of Ca2+ signaling in the oocyte are oocyte activation and fertilization. Oocyte activation, driven by sperm-specific phospholipase PLCζ, is initiated by concerted intracellular patterns of Ca2+ release, termed Ca2+ oscillations. Ca2+ oscillations persist for a long time during fertilization and are coordinately engaged by a variety of Ca2+ channels, pumps, regulatory proteins and their partners. Calcium signaling also regulates granulosa and cumulus cells' function, which further affects oocyte maturation and fertilization outcome. Clinically, there are several physical and chemical options for treating fertilization failure through oocyte activation. Additionally, various exogenous compounds or drugs can cause ovarian dysfunction and female infertility by inducing abnormal Ca2+ signaling or Ca2+ dyshomeostasis in oocytes and granulosa cells. Therefore, the reproductive health risks caused by adverse stresses should arouse our attention. This review will systematically summarize the latest research progress on the aforementioned aspects and propose further research directions on calcium signaling in female reproduction.

How Do Environmental Toxicants Affect Oocyte Maturation Via Oxidative Stress?

In mammals, oogenesis initiates before birth and pauses at the dictyate stage of meiotic prophase I until luteinizing hormone (LH) surges to resume meiosis. Oocyte maturation refers to the resumption of meiosis that directs oocytes to advance from prophase I to metaphase II of meiosis. This process is carefully modulated to ensure a normal ovulation and successful fertilization. By generating excessive amounts of oxidative stress, environmental toxicants can disrupt the oocyte maturation. In this review, we categorized these environmental toxicants that induce mitochondrial dysfunction and abnormal spindle formation. Further, we discussed the underlying mechanisms that hinder oocyte maturation, including mitochondrial function, spindle formation, and DNA damage response.

Embryological characteristics and clinical outcomes of oocytes with different degrees of abnormal zona pellucida during assisted reproductive treatment.

Abnormalities in the zona pellucida (ZP) adversely affect oocyte maturation, embryo development and pregnancy outcomes. However, the assessment of severity is challenging. To evaluate the effects of different degrees of ZP abnormalities on embryo development and clinical outcomes, in total, 590 retrieval cycles were scored and divided into four categories (control, mild, moderate and severe) based on three parameters: perivitelline space, percentage of immature oocytes and percentage of oocytes with abnormal morphology. As the severity of abnormal ZP increased, both the number of retrieved oocytes and mature oocytes decreased. The fertilization rate did not differ significantly among groups. The rates of embryo cleavage and day-3 high-quality embryos in the mild group and the moderate group did not vary significantly between the two groups but were significantly higher than those in the severe group. The blastulation rates of the abnormal ZP groups were similar; however, they were lower than those of the control group. Moreover, the cycle cancellation rate of the severe abnormal ZP group was as high as 66.20%, which was significantly higher than that of the other three groups. Although the rates of cumulative clinical pregnancy and live births were lower than those in the control group, they were comparable among the abnormal ZP groups. There were no differences in the neonatal outcomes of the different groups. Together, ZP abnormalities show various degrees of severity, and in all patients regardless of the degree of ZP abnormalities who achieve available embryos, there will be an opportunity to eventually give birth.

Follistatin (FST) is expressed in buffalo (Bubalus bubalis) ovarian follicles and promotes oocyte maturation and early embryonic development.

Follistatin (FST), a member of the transforming growth factor-β (TGF-β) superfamily, has been identified as an inhibitor of follicle-stimulating hormone. Previous studies showed that it plays an important role in animal reproduction. Therefore, this study aims to investigate its effect on the maturation of buffalo oocytes invitro, and the underlying mechanism of FST affecting oocyte maturation was also explored in buffalo cumulus cells. Results showed that FST was enriched in the ovary and expressed at different stages of buffalo ovarian follicles as well as during oocyte maturation and early embryo development. The FST expression level was up-regulated in MII buffalo oocytes compared with the GV stage (p < .05). To study the effects of FST on buffalo oocytes' maturation and early embryonic development, we added the pcD3.1 skeleton vector and PCD3.1-EGFP-FST vector into the maturation fluid of buffalo oocytes, respectively. It was demonstrated that FST promoted the invitro maturation rate of buffalo oocytes and the blastocyst rate of embryos cultured invitro (p < .05). By interfering with FST expression, we discovered that FST in cumulus cells plays a crucial role in oocyte maturation. Interference with the FST expression during the buffalo oocyte maturation did not affect the first polar body rate of buffalo oocyte (p > .05). In contrast, the location of mitochondria in oocytes was abnormal, and the cumulus expansion area was reduced (p < .05). After parthenogenetic activation, the cleavage and blastocyst rates of the FST-interfered group were reduced (p < .05). Furthermore, RT-qPCR was performed to investigate further the underlying mechanism by which FST enhances oocyte maturation. We found that overexpression of FST could up-regulate the expression level of apoptosis suppressor gene Bcl-2 and TGF-β/SMAD pathway-related genes TGF-β, SMAD2, and SMAD3 (p < .05). In contrast, the expression levels of SMAD4 and pro-apoptotic gene BAX were significantly decreased (p < .05). The FST gene could affect buffalo oocyte maturation by regulating the oocyte mitochondria integrity, the cumulus expansion, cumulus cell apoptosis, and the expression levels of TGF-β/SMAD pathway-related genes.

Should the trigger to oocyte retrieval interval be different in progestin-primed ovarian stimulation cycles?

Research questionDoes the trigger to oocyte retrieval interval (TORI) affect oocyte maturation rates differently in progestin-primed ovarian stimulation (PPOS) and gonadotrophin-releasing hormone (GnRH) antagonist cycles? DesignThis was a retrospective cohort study. The interaction between the stimulation protocol and TORI was assessed in a linear mixed effects multivariable regression analysis with oocyte maturation rate as the dependent variable, and stimulation protocol (GnRH antagonist or PPOS), age (continuous), gonadotrophin type (FSH or human menopausal gonadotrophin), trigger (human chorionic gonadotrophin [HCG] or GnRH agonist), TORI (continuous) and days of stimulation (continuous) as the independent variables. Oocyte maturation rate was defined as number of metaphase II oocytes/number of cumulus–oocyte complexes retrieved. The maturation rate was calculated per cycle and treated as a continuous variable. ResultsA total of 473 GnRH antagonist and 205 PPOS cycles (121 conventional PPOS and 84 flexible PPOS) were analysed. The median (quartiles) female age was 36 (32–40) years. Of these cycles, 493 were triggered with HCG and 185 with a GnRH agonist. The TORI ranged between 33.6 and 39.1 h, with a median (quartiles) of 36.2 (36–36.4) hours. Maturation rates were similar between fixed PPOS, flexible PPOS and antagonist cycles (median 80%, 75% and 75%, respectively, P = 0.15). There was no significant interaction between the stimulation protocols and TORI for oocyte maturation. ConclusionsPPOS cycles do not seem to require a longer TORI than GnRH antagonist cycles.

Down-regulation of Lon protease 1 lysine crotonylation aggravates mitochondrial dysfunction in polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a prevalent reproductive endocrine disorder, with metabolic abnormalities and ovulation disorders. The post-translational modifications (PTMs) are functionally relevant and strengthen the link between metabolism and cellular functions. Lysine crotonylation is a newly identified PTM, the function of which in PCOS has not yet been reported. To explore the molecular mechanisms of crotonylation involved in the abnormalities of metabolic homeostasis and oocyte maturation in PCOS, by using liquid chromatography-tandem mass spectrometry analysis, we constructed a comprehensive map of crotonylation modifications in ovarian tissue of PCOS-like mouse model established by dehydroepiandrosterone induction. The crotonylation levels of proteins involved in metabolic processes were significantly decreased in PCOS ovaries compared to control samples. Further investigation showed that decrotonylation of Lon protease 1 (LONP1) at lysine 390 was associated with mitochondrial dysfunction in PCOS. Moreover, LONP1 crotonylation levels in PCOS were correlated with ovarian tissue oxidative stress levels, androgen levels, and oocyte development. Consistently, down-regulation of LONP1 and LONP1 crotonylation levels were also observed in the blood samples of PCOS patients. Collectively, our study revealed a mechanism by which the decrotonylation of LONP1 may attenuate its activity and alter follicular microenvironment to affect oocyte maturation in PCOS.

Melatonin Supplementation during In Vitro Maturation of Porcine Oocytes Alleviates Oxidative Stress and Endoplasmic Reticulum Stress Induced by Imidacloprid Exposure.

Imidacloprid (IMI) is an endogenous neonicotinoid insecticide widely used in agriculture and has attracted researchers' attention because of its risks to the environment and human health. Melatonin (MT) is an antioxidant hormone produced by the pineal gland of the brain. Studies have shown that it has a variety of physiological functions and plays a crucial role in the development of animal germ cells and embryos. The potential protective effects of MT against oocyte damage caused by neonicotinoid pesticide toxicity remain unclear. In this study, we report the toxicity of IMI against, and its effects on the quality of, porcine oocytes and the protective effect of MT on IMI-exposed oocytes. The results show that IMI exposure adversely affected oocyte maturation, while MT supplementation ameliorated its toxic effects. Specifically, IMI exposure increased oxidative stress (OS), endoplasmic reticulum stress (ERS), and apoptosis, which may affect polar body expulsion rates and blastocyst formation. Also, IMI exposure reduced oocyte cleavage rates and the number of cells in blastocysts. However, all of these toxic effects can be restored after a melatonin supplementation treatment. In conclusion, these results suggest that melatonin has a protective effect on IMI-induced defects during porcine oocyte maturation.

P-638 Impact of amphiregulin on oocyte maturation and embryo quality in patients with the polycystic ovarian syndrome.

Abstract Study question Does the concentration of amphiregulin in the follicular fluid affect oocyte maturation and embryo quality in patients with polycystic ovarian syndrome? Summary answer The concentration of amphiregulin affects oocyte maturity and embryo quality in patients with polycystic ovarian syndrome and can be used as a predictive biomarker. What is known already Polycystic ovary syndrome (PCOS) is a common metabolic dysfunction and heterogeneous endocrine disorder in women of reproductive age. Epidermal growth factor receptors and their ligands, such as amphiregulin, which are expressed in female reproductive tissues, have been shown to regulate various important reproductive functions. Amphiregulin is reportedly involved in oocyte maturation through autocrine and paracrine mechanisms, however, the impact of amphiregulin on oocyte maturity end embryo quality in patients diagnosed with POCS which goes under controlled ovarian stimulation remains unknown. Determination of potential biomarkers might be the key to successful IVF outcomes. Study design, size, duration The study consisted of a total of 87 oocytes obtained from 30 patients who underwent ICSI at UKS Homburg (Germany) between October 2021 and March 2022. Fifteen patients were diagnosed with polycystic ovary syndrome while the other fifteen were fertile without any diagnosis. For the study purpose, follicles were aspirated separately, and the follicular fluid was centrifuged for 5 min at 1,500×g. After the preparation, the supernatant was removed and stored at -20 °C until analysis. Participants/materials, setting, methods Concentrations of amphiregulin in follicular fluid were determined by using a commercially available sandwich ELISAkit (Duo Set; R&amp;D Systems Inc., Minneapolis) in accordance with the manufacturer’s instructions. Good embryo quality (GQE) on day 3 was defined as a 7-9 cell stage embryo with less than 25% of fragmentation and with equally sized blastomeres. Between-group comparisons were conducted with a Mann-Whitney test. Logistic regression analysis was used to determine the influence of amphiregulin on studied parameters. Main results and the role of chance The mean age of all patients was 33.5 (±5.2) years. Patients included in the study were stimulated according to a gonadotropin-releasing hormone (GnRH) antagonist protocol. Out of the 87 oocytes, 59 (67.8%) were at MII stadium, 13 (14.9%) were at MI and 8 (9.1%) were at GV stadium. ICSI was done only with MII and MI oocytes and the fertilization rate was 70.1% (61 oocytes were fertilized out of 72). Obtained results showed that concentrations of amphiregulin were significantly lower in follicular fluid of PCOS patients [(107.00(51.95-131.00) ng/mL vs 115.27(43.19-209.51) ng/mL) respectively; p = 0.024]. Data comparisons between mature and immature oocytes indicated that amphiregulin concentration was significantly higher in follicles where mature oocytes were developed [(117.50 (65.99-209.51) ng/mL vs 81.75(43.19-128.20) ng/mL) respectively; p &amp;lt; 0.0001]. Additionally, logistic regression analysis confirmed the positive effect of amphiregulin concentration on oocyte maturity (p &amp;lt; 0.001). Out of the 61 fertilized oocytes, 36 (59.0%) formed good-quality embryos. Additional analysis indicated that oocytes that developed into good-quality embryos came from follicles where amphiregulin concentrations were significantly higher compared to those that developed into poor-quality embryos [(124.05 (91.88-209.51) ng/mL. vs 86.72(43.19-109.40) ng/mL) respectively; p &amp;lt; 0.001]. Logistic regression analysis confirmed the positive effect of amphiregulin concentration on embryo quality (p &amp;lt; 0.01). Limitations, reasons for caution The limitation of the presented study was the relatively small patient cohort. Although the pregnancy rate in the presented study was 27.8 % , single embryo transfer was not performed, therefore further research should link amphiregulin concentrations with the pregnancy rate as well. Wider implications of the findings Results obtained in the study might be useful for further handling of PCOS patients since the literature already confirmed that PCOS patients produce an increased number of mature oocytes, so culture medium-containing amphiregulin might be a future solution for those patients. Trial registration number 146/19

Artesunate does not affect oocyte maturation and early embryo development of bovine

Despite the cytotoxicity and embryotoxicity previously reported artesunate is a recommended drug to treat malaria for adults, children, and women in the first trimester of pregnancy. To address the putative effects of artesunate on female fertility and preimplantation embryo development, when the pregnancy is not detectable yet, artesunate was added to the oocyte in vitro maturation and in vitro embryo development of bovine. Briefly, in experiment 1 the cumulus-oocyte complexes (COCs) were in vitro matured for 18 h with 0.5, 1, or 2 µg/mL of artesunate or not (negative control) and then checked for nuclear maturation and subsequent embryo development. In experiment 2, the COCs were in vitro matured and fertilized without artesunate, which was added (0.5, 1, or 2 µg/mL) from the 1st to the 7th day of embryo culture along with a negative and a positive control group with doxorubicin. As a result, the use of artesunate on oocyte in vitro maturation did not differ from the negative control (p > 0.05) regarding nuclear maturation, cleavage, and blastocyst formation. Also, artesunate on in vitro embryo culture did not differ from negative control (p > 0.05) regarding cleavage and blastocyst formation, except for positive control, with doxorubicin (p < 0.05). In conclusion, under the conditions investigated, there was no evidence of artesunate toxicity on oocyte competence and the preimplantation period of in vitro embryo development in the bovine model, however, artesunate use still should be taken carefully as the outcome of implantation after oocytes and blastocysts exposure to artesunate remains unknown.

Exposure to acrylamide induces zygotic genome activation defects of mouse embryos.

Acrylamide (ACR) is an important chemical raw material for wastewater treatment, paper industry and textile industry, which is widely exposed from occupational, environmental and dietary situation. ACR has neurotoxicity, genotoxicity, potential carcinogenicity and reproductive toxicity. Recent study indicates that ACR affected oocyte maturation quality. In the present study, we reported the effects of ACR exposure on zygotic genome activation (ZGA) in embryos and its related mechanism. Our results showed that ACR treatment caused 2-cell arrest in mouse embryos, indicating the failure of ZGA, which was confirmed by decreased global transcription levels and aberrant expression of ZGA-related and maternal factors. We found that histone modifications such as H3K9me3, H3K27me3 and H3K27ac levels were altered, and this might be due to the occurrence of DNA damage, showing with positive γ-H2A.X signal. Moreover, mitochondrial dysfunction and high levels of ROS were detected in ACR treated embryos, indicating that ACR induced oxidative stress, and this might further cause abnormal distribution of endoplasmic reticulum, Golgi apparatus and lysosomes. In conclusion, our results indicated that ACR exposure disrupted ZGA by inducing mitochondria-based oxidative stress, which further caused DNA damage, aberrant histone modifications and organelles in mouse embryos.