Search Results (695)

Background/Objectives: Oxidative stress is a major cause of impaired oocyte quality and early embryo development, a challenge that still needs to be addressed in assisted reproduction. Mesenchymal stem cell secretomes have been investigated as cell-free therapeutics with antioxidant activity and relevant anti-apoptotic effects. This study aimed to evaluate the effects of human amniotic membrane-derived mesenchymal stem cell-conditioned saline (AMSC-CS) as an injectable formulation on oxidative stress–related markers in ovarian tissue and preimplantation developmental outcomes. Methods: AMSC-CS was administered intravenously to female mice in a dose-dependent manner. Safety assessments were conducted to evaluate systemic and target organ toxicity within the dosage range. In vitro fertilization (IVF) outcomes and oxidative status in ovaries, oocytes, and embryos were evaluated following treatment with low, medium, and high doses of AMSC-CS (1, 3, and 5 μL/g). Results: As an injectable formulation, the safety assessments did not reveal systemic or target organ toxicity of AMSC-CS within the dosage range. Medium-to-high doses of AMSC-CS improved the expression of folliculogenesis-related genes and decreased oxidative stress and apoptosis signaling in ovarian tissue. At the high dose, AMSC-CS promoted preimplantation embryo development to the blastocyst and hatched blastocyst stages, along with improved blastocyst quality and reduced oxidative stress in oocytes and blastocysts. Conclusions: These findings suggest that AMSC-CS at medium-to-high doses, as an injectable formulation with antioxidant activity, may be a promising adjunct for assisted reproductive technologies. Full article

The hallmark feature of empty follicle syndrome (EFS) is failure to retrieve oocytes from apparently mature follicles despite adequate ovarian stimulation and appropriate ovulation triggering. Although considered uncommon, with a reported prevalence ranging from 0.2% to 7%, EFS may have a profound clinical and psychological impact and can recur in assisted reproductive technology (ART) cycles. Modern classification systems divide EFS into genuine and false forms. Genuine EFS is potentially associated with intrinsic abnormalities involving luteinizing hormone/choriogonadotropin receptor (LHCGR) signaling, oocyte competence, and cumulus–oocyte interaction, whereas false EFS is primarily attributed to pharmacokinetic or pharmacodynamic factors resulting in inadequate trigger exposure. Borderline EFS represents a third phenotype characterized by incomplete or partial impairment of final oocyte maturation. This review examines the pharmacodynamics of ovulation-triggering agents, including human chorionic gonadotropin (hCG), gonadotropin-releasing hormone (GnRH) agonist protocols, and dual-trigger strategies, and their roles in regulating final oocyte maturation. The molecular aspects of periovulatory signal transduction and the mechanisms of LHCGR activation, epidermal growth factor (EGF)-like pathways, and meiotic resumption in relation to EFS etiopathogenesis will be described. The impact of patient-dependent conditions like obesity, poor ovarian reserve, polycystic ovary syndrome (PCOS), and pituitary response on trigger response will be assessed. New approaches like post-trigger monitoring of hormones and rescue treatment with gonadotropins represent a valuable method for avoiding cycle cancellation in patients at risk. Overall, EFS is increasingly regarded not as a single disorder but as a heterogeneous spectrum of periovulatory dysfunction arising from pharmacological, endocrine, and intrinsic ovarian factors that impair completion of final oocyte maturation. Full article

Carnosine is a naturally occurring endogenous dipeptide with great potential to improve reproductive function and fertility. In this study, supplementation of 1 μg/mL carnosine during in vitro maturation (IVM) significantly enhanced the developmental competence and quality of the resulting bovine embryos. Carnosine treatment effectively elevated mitochondrial membrane potential, mitochondrial activity, and ATP content in oocytes. Moreover, it strengthened the antioxidant and anti-apoptotic capacities of oocytes, as evidenced by reduced intracellular reactive oxygen species (ROS) levels, lowered DNA damage and an early apoptosis rate, alongside increased glutathione (GSH) content, an elevated BCL2/BAX mRNA ratio, and upregulation of antioxidant genes SOD1, CAT, GPx1, and GPx4. Notably, combined application of 1 μg/mL carnosine during IVM and 10⁻⁷ M melatonin during in vitro culture (IVC) synergistically improved both blastocyst development and quality. Collectively, these findings provide novel evidence supporting the therapeutic potential of carnosine in optimizing in vitro embryo production in bovine, and highlight the value of stage-specific supplementation strategies to further improve embryonic development efficiency. Full article

Reproductive inefficiency associated with impaired oocyte competence and embryonic loss remains a major limitation in livestock production. Although glycine is classified as a non-essential amino acid, its endogenous synthesis is often insufficient to meet increased metabolic demands during gestation and early embryonic development. This suggests that glycine has a conditionally essential role in reproductive physiology. However, the mechanisms through which glycine integrates metabolic and signaling processes to regulate reproductive outcomes are not fully understood. This review summarizes the recent advances in understanding glycine’s role in animal reproduction, emphasizing its function as a metabolic regulator rather than merely a structural component. Glycine contributes to reproductive processes by maintaining redox homeostasis, supporting mitochondrial function and stabilizing cellular environments as part of its osmolyte function during critical developmental stages. Additionally, glycine participates in one-carbon metabolism, influencing nucleotide synthesis and epigenetic regulation. Furthermore, emerging evidence suggests that glycine may modulate key signaling pathways, including the AMP-activated protein kinase (AMPK)-mechanistic target of rapamycin complex 1 (mTORC1) pathway. Consistent with these mechanistic roles, glycine supplementation has been associated with improvements in oocyte maturation and embryonic development, particularly in vitro. These findings highlight the potential of glycine as a dietary or culture medium supplement to enhance reproductive performance in livestock. However, most current evidence is derived from in vitro systems, and the translation of these findings into livestock production strategies requires validation through well-designed in vivo studies. Full article

Oocyte formation occurs successfully within a meticulously controlled follicular environment characterized by well-documented endocrine, metabolic, and paracrine signals. Yet, the immunological landscape of the follicle and its role in influencing oocyte competency has received less attention in research. Growing research indicates that the ovarian follicle functions as an immunological-active niche necessitating a precise equilibrium between controlled inflammation and targeted immune tolerance. The programmed cell death-1 (PD-1) receptor and its ligand PD-L1 constitute a crucial immune checkpoint pathway, essential for sustaining peripheral immunological tolerance and averting excessive immune activation. Despite their comprehensive research in cancer biology and maternal–fetal interactions, their possible function in the follicular microenvironment remains mostly unexamined. We propose that PD-1/PD-L1 signaling may facilitate the formation of a localized immune-tolerant milieu inside the follicle to safeguard the developing oocyte from inflammatory injury and immune-mediated stress. The disturbance of this suggested equilibrium may lead to a pro-inflammatory follicular environment, compromised granulosa cell function, and modified oocyte maturation, hence affecting fertilization and embryonic developmental potential. In clinical contexts with immunological dysregulation, such as endometriosis, polycystic ovarian syndrome, and unexplained IVF failure, such processes may be especially significant. The purpose of this narrative review is to assimilate the current comprehension of immune regulation in the follicle with the established biology of PD-1/PD-L1 and to investigate a potential correlation between immune checkpoint signaling, oocyte competence, and assisted reproductive outcomes. Considering the follicle as an immune-regulated microenvironment offers a new paradigm for comprehending infertility and identifying novel indicators or therapeutic targets. Full article

Improvement in the in vitro maturation (IVM) of oocyte quality is a gateway to enhancing the efficiency of in vitro embryo production. The anti-Müllerian hormone (AMH) is a crucial hormone secreted by granulosa cells that effectively suppresses primordial follicle recruitment and regulates follicular growth and development. This study was designed to investigate the role of AMH on the IVM of sheep oocytes. In this current study, oocytes in vitro were cultured in media supplemented with AMH. We comprehensively analyzed the impact of AMH on various developmental parameters of sheep oocytes, such as cellular activity, cortical granules (CGs) migration, cytoskeleton and mitochondrial function of oocytes. Furthermore, Smart-seq2 single-cell RNA sequencing (scRNA-seq) was employed to elucidate the oocytes’ development. The results showed that treatment with 100 ng/mL improved the maturation rate of the oocytes, the normal distribution rate of cortical granules and mitochondrial function, while reducing the rate of spindle abnormalities in oocytes. A total of 741 differentially expressed genes (DEGs) were observed between the FSH_12 h and AMH_12 h groups, and 746 DEGs were observed between the FSH_24 h and A+F groups. KEGG pathway analysis revealed that the FSH_12 h and AMH_12 h groups significant enrichment in DEGs were associated with p53, MAPK, PI3K-Akt and TGF-beta signaling pathways, and the FSH_12 h and AMH_24 h groups significant enrichment in DEGs were associated with cAMP, AMPK, Hedgehog and estrogen signaling pathways. These findings suggest that AMH may regulates oocytes IVM via several candidate signaling pathways. Our results provide preliminary clues for exploring the regulatory mechanism of sheep oocyte maturation and optimizing relevant culture systems. Full article

WEE2, an oocyte-specific kinase of the WEE family, is a core regulator of oocyte meiosis. It maintains germinal vesicle (GV) arrest and prevents premature meiotic resumption by phosphorylating cyclin-dependent kinase 1 (CDK1), thereby inhibiting maturation-promoting factor (MPF) activity. WEE2 also regulates exit from metaphase II (MII), ensuring orderly meiotic progression. Consequently, the functional integrity of WEE2 is essential for female reproduction. Homozygous or compound heterozygous mutations in the WEE2 gene represent a major genetic cause of total fertilization failure and primary infertility, as these mutations lead to reduced or abolished kinase activity, impair meiotic control, and disrupt oocyte maturation and embryonic development. This review systematically summarizes the protein structure, core functions, and mutation types of WEE2, along with its association with total fertilization failure and female primary infertility. It also highlights research advances in WEE2-targeted inhibitors and discusses the potential applications and future directions of WEE2 in the diagnosis and management of reproductive disorders. Full article

Granulosa cells (GCs), an element of the ovarian follicle, are crucial for oocyte maturation, folliculogenesis, and steroidogenesis. Granulosa cells play a crucial role in fertilization by providing metabolic and hormonal support to the oocyte, maintaining its quality and regulating its meiotic arrest. Oocyte quality and fertilization efficiency depend on the proper activity of GCs, especially their mutual communication, providing metabolic support and protecting against oxidative stress. When interrupted, they may take part in the pathogenesis of polycystic ovary syndrome, premature ovarian failure, primary ovarian insufficiency, and diminished ovarian reserve. GCs are enclosed in the antrum where they communicate with surrounding cells, create a dynamic microenvironment, and regulate hormone biosynthesis. To analyze molecular mechanisms regulating endogenous signaling, it is important to consider the dynamic transcriptomic response of porcine GCs during in vitro culturing over 48, 96, and 144 h. Transcriptomic analysis revealed a variable and dynamic transcriptional upregulation of genes associated with cellular response to endogenous and external stimuli, chemical compound metabolism, vascular development, and GCs migration. Also, proven by Gene Ontology (GO) enrichment analysis, the following terms were highlighted: “cellular response to chemical stimulus” and “cellular response to organic substance”. Specific genes, such as HSD3B1, POSTN, LOX, SERPINB2, ITGB3, ANKRD1, SLC1A1, and SFRP2, exhibited significant expression changes, suggesting extensive GCs self-regulation and metabolism changes. Further analysis indicates improvements in cellular response to a cytokine stimulus, growth factor response, hormone response, enzyme-linked receptor protein signaling, and positive regulation of cell migration. These findings suggest interweaving of regulatory mechanisms underlying intercellular communication in GCs during in vitro culturing, despite the lack of signals from the native ovarian environment. Further investigating interplays of detecting pathways will provide a more comprehensive understanding and even insights into the potential clinical use of the knowledge about the role of GCs in folliculogenesis, oocyte maturation and ovulation. Full article

Metformin (MET) plays crucial regulatory roles in mammalian oocyte meiosis, yet the concentration-dependent biphasic impacts of MET on porcine oocyte in vitro maturation (IVM) and the related molecular mechanisms remain poorly clarified. This study aimed to explore the distinct effects and underlying pathways of low- and high-dose MET in porcine oocytes. Different concentrations of MET (0, 7.5, 15, 30, 150, and 300 μM) were supplemented during oocyte IVM, with phenotypic detection, untargeted metabolomic analysis, and Nrf2 inhibitor (ML385) intervention performed for mechanism exploration. Results showed that 15 μM low-dose MET facilitated oocyte maturation, mitochondrial function and redox balance, while 300 μM high-dose MET caused obvious developmental damage. Mechanistically, low-dose MET triggered noncanonical AMPK activation independent of the AMP/ATP ratio and enhanced AMPK–Nrf2 antioxidant signaling, whereas high-dose MET induced energy stress and oxidative injury via inhibiting mitochondrial complex I. Blockade of Nrf2 further abolished the protective effects of low-dose MET. Collectively, this finding illustrates the biphasic actions of MET on porcine oocytes and provides a theoretical reference for optimizing porcine in vitro embryo production. Full article

In highly variable estuarine environments, short-lived fishes must balance immediate reproduction against future growth, yet the reproductive role of maternal size remains poorly resolved. Here, we analyzed biological surveys of the yellowfin goby Acanthogobius flavimanus from Haizhou Bay, Yellow Sea, collected between 2023 and 2025, combining fecundity estimation, egg morphometry, histology, and size-structured reproductive-output modeling. Absolute fecundity scaled hyperallometrically with total length (β = 3.18, 95% CI: 3.05–3.31, R² = 0.71, p < 0.001), while mean egg diameter increased significantly with maternal size (R² = 0.65, p < 0.001), yielding an approximately 3.15-fold increase in estimated egg volume across the observed size range. Histology revealed contrasting ovarian developmental phenotypes within the same spring cohort: a precocious phenotype with active vitellogenesis and a delayed-development phenotype with structurally intact early-stage oocytes and higher condition factor. Relative Reproductive Output (RRO) modeling showed that females > 180 mm total length represented only 4.8% of abundance but contributed 18.5% of total standardized egg-production output under the assumptions of the model. Inter-annual monitoring further indicated a decline in mean body size and in the proportion of large individuals from 2023 to 2025, a pattern consistent with size truncation but requiring longer-term monitoring for causal attribution. These findings suggest that large females can contribute disproportionately to reproductive output even in a short-lived estuarine fish and support the inclusion of size structure in fisheries assessment and management. Full article

Ovarian granulosa cells (GCs) ensure proper follicular development and oocyte maturation through gap-junction-mediated intercellular communication. Zearalenone (ZEA), a mycotoxin with estrogen-like activity, specifically targets and impairs ovarian function. Most existing studies have focused on ZEA-induced apoptosis in GCs, but whether ZEA disrupts gap junctions in ovarian GCs remains unclear. Therefore, the aim of this study was to investigate whether and how ZEA induces gap junction injury in ovine ovarian GCs, with a particular focus on the roles of G protein-coupled receptor 30 (GPR30), oxidative stress, and the NLRP3 inflammasome. In the present study, primary ovine ovarian GCs were isolated, cultured, and treated with different concentrations of ZEA to establish a gap junction injury model, and specific inhibitors/antagonists were used to investigate the underlying mechanisms. The results showed that ZEA decreased granulosa cell viability and significantly inhibited the expression of the gap junction proteins Connexin 43 (Cx43) and Connexin 37 (Cx37) in a concentration-dependent manner. ZEA treatment also significantly upregulated the expression of the NOD-like receptor familypyrindomain containing 3 (NLRP3) inflammasome-related proteins (NLRP3, ASC, Cleaved Caspase-1, and the downstream pro-inflammatory cytokine IL-1β) in a concentration-dependent manner. Pretreatment with the NLRP3-specific inhibitor MCC950 significantly reversed ZEA-induced downregulation of Cx43 and Cx37 and effectively blocked NLRP3 inflammasome activation, indicating that NLRP3 is a key target in ZEA-induced gap junction injury. Further experiments confirmed that ZEA treatment significantly increased oxidative stress levels in granulosa cells; pretreatment with the reactive oxygen species (ROS) scavenger N-acetylcysteine (NAC) restored the ZEA-induced downregulation of Cx43 and Cx37 and suppressed NLRP3 inflammasome activation, suggesting that ROS acts as an upstream regulator of NLRP3 inflammasome activation. Moreover, ZEA treatment altered GPR30 expression levels, and pretreatment with the GPR30 antagonist G15 effectively inhibited ZEA-induced ROS production, NLRP3 inflammasome activation, and downregulation of Cx43/Cx37, indicating that ZEA exerts its effects through functional activation of GPR30. Collectively, ZEA activates the GPR30 receptor, induces ROS accumulation in granulosa cells, and subsequently triggers NLRP3 inflammasome activation, ultimately leading to downregulation of Cx43 and Cx37 and gap junction dysfunction. This study reveals a previously unrecognized molecular mechanism by which ZEA induces gap junction injury in ovarian GCs, providing potential therapeutic targets and a theoretical basis for preventing ZEA-induced ovarian dysfunction and improving animal reproductive health. Full article

Epigenetic regulation is pivotal in reproductive processes, such as oocyte maturation and pre-implantation embryonic development, and it impacts gene expression without altering DNA sequence through mechanisms including DNA methylation, histone modifications, and non-coding RNAs. Primarily, microRNA-21 is involved in meiotic progression, apoptosis, and cumulus cell function, which are necessary for oocyte competency. miR-21 dysregulation can lead to improper oocyte maturation and poor embryonic development, ultimately causing developmental defects. During pre-implantation embryonic development, DNA methylation and histone modifications contribute to cellular reprogramming, ensuring proper gene activation and repression. Environmentally, endocrine disruptors affect miR-21 expression, potentially disrupting pathways involved in reproductive health and developmental programming. Overall, this review explores the correlation between epigenetics, miRNA regulation, and environmental factors, emphasizing the intricacies of oocyte maturation and pre-implantation embryonic development. This highlights the need for additional mechanistic and translational research in reproductive epigenetics. Full article

Background/Objectives: Statins are currently one of the most commonly used cholesterol-lowering drugs. In recent years, in addition to their well-known effects on the cardiovascular system, statins have been shown to exert beneficial effects in the progression of various neuropsychiatric and neurodegenerative diseases. Methods: In this study, the effects of lovastatin on the function of α7-nicotinic acetylcholine (nACh) receptors expressed in rat hippocampus and Xenopus oocytes were investigated. Results: In whole-cell patch clamp studies in hippocampal neurons, 21-day chronic (20 mg/kg), but not acute (20 min), lovastatin treatment caused significant potentiation of choline (a selective agonist for α7 nACh receptors)-induced currents and choline-induced increases in GABA_A receptor-mediated currents. Further studies in Xenopus oocytes expressing human α7-nACh receptors indicated that 72 h pretreatment with lovastatin caused a significant increase in α7-nACh receptor function with an EC₅₀ value of 296 nM. Other statins, such as simvastatin and pravastatin, also potentiated α7-nACh receptors. Potentiation by lovastatin treatment was associated with a significant decrease in oocyte cholesterol content and was diminished by Go6983, an inhibitor of protein kinase C (PKC), suggesting that both decreased cholesterol levels and activation of PKC are involved in statin potentiation of α7-nACh receptors. Conclusions: In conclusion, our findings indicate that chronic lovastatin treatment potentiates the function of α7-nACh receptors in hippocampal neurons and in Xenopus oocytes expressing human α7-nACh receptors and provides important insights that could guide future efforts to design novel drugs targeting α7-nACh receptors. Full article

Background: The regulation of inorganic phosphate (Pi) homeostasis is predominantly mediated by the Pi transporters belonging to the SLC34 and SLC20 families of solute carriers. However, not all Pi handling can be explained by these transporters. In this study, we sought to identify novel Pi transporters in accordance with prior findings on inhibition patterns. Methods: We have performed a functional screening of new Pi carriers using the Xenopus laevis oocyte expression system, focusing on the SLC26 family, and corroboration in cell culture. Results: Both SLC26A7 and SLC26A9 have been shown to express sodium-activated Pi uptakes with approximately 200 µmol/L Pi affinity. In both cases, Pi transport is inhibited by increasing pH and by phosphonoformate, arsenate, bicarbonate, sulfate, the chloride channel inhibitor 5-nitro-2-[(3-phenylpropyl)amino]-benzoate, and several transport site and translocation inhibitors of bicarbonate exchangers. In addition, the CFTR inhibitor GlyH-101 and the SLC4 inhibitors DIDS, SITS, and phloretin exhibited partial inhibition of SLC26A9-mediated Pi uptake. The endogenous expressions of both SLC26A7 and SLC26A9 in the renal cell lines LLC-PK1 and MDCK were primarily intracellular, colocalizing with endosomes, lysosomes, and the trans-Golgi network markers. Conversely, plasma membrane expression was found to be minimal. Pi transport in MDCK cells was sodium-independent, but when either SLC26A7 or SLC26A9 was overexpressed, sodium-activated Pi uptake was observed, along with increased expressions of SLC26A7 or SLC26A9 in the plasma membrane. Conclusions: Sodium-activated Pi transport is a novel function of the SLC26A7 and SLC26A9 multifunctional anion transporters. Further research is necessary to ascertain the relevance to Pi homeostasis in vivo. Full article

Natural pigment lycopene (LYC), a carotenoid, possesses antioxidant, anti-apoptotic, anticancer, and immunoenhancing properties. During in vitro culture, this substance protects oocytes and early embryos from damage caused by reactive oxygen species (ROS), thereby enhancing the in vitro maturation (IVM) rate of oocytes and the developmental competence of early embryos. This study aimed to investigate the effects of supplementing different concentrations of LYC (0, 5, 10, and 15 μM) during in vitro culture of sheep oocytes and early embryos on their developmental competence. In contrast to the control group, the 5 μM LYC treatment group displayed a marked increase in the first polar body extrusion rate and the extent of cumulus cell expansion, as well as a significantly higher proportion of normal spindle assembly in sheep oocytes, but 15 μM LYC appeared to negatively affect oocyte maturation. Relative to all other experimental groups, the 5 μM LYC treatment group displayed significantly elevated rates of cleavage and blastocyst rate during early in vitro embryonic development. The levels of ROS in mature oocytes and early embryos were significantly decreased, whereas the GSH level was significantly elevated. Furthermore, LYC treatment significantly enhanced mitochondrial activity and markedly elevated the mitochondrial membrane potential (MMP) in mature oocytes and early embryos. Moreover, the total cell number of blastocysts was significantly increased. Moreover, in early embryos, the transcript levels of genes associated with both oxidative stress and apoptosis were favorably regulated. In conclusion, LYC supplementation boosted the rates of oocyte maturation and blastocyst formation in sheep, while elevating the developmental capacity of early embryos. Full article