Search Results (14)

One of the major factors causing reduced developmental capacity of aged porcine oocytes is the induction of oxidative stress during oocyte aging. Tauroursodeoxycholic acid (TUDCA) supports cellular function by acting as an antioxidant and free radical scavenger. The aim of this study is to evaluate whether exogenous supplementation of TUDCA to the porcine in vitro maturation system can ameliorate the compromised quality of aged oocytes by mitigating free radical production. We found that TUDCA was able to effectively maintain normal oocyte morphology, cortical granule distribution, and spindle structure during postovulatory aging. Additionally, the blastocyst rate and total cell number in blastocysts were significantly increased in aged porcine oocytes treated with TUDCA. Importantly, aged porcine oocytes treated with TUDCA reduced ROS levels, increased the expression levels of GSH and SOD1 genes, and improved the mitochondrial membrane potential ratio. Further study demonstrated that TUDCA significantly alleviated apoptosis in aged porcine oocytes, confirmed by the decreased Caspase 3 levels and ratio of BAX to BCL2. Interestingly, TUDCA could effectively alleviate the phenomenon of endoplasmic reticulum stress triggered during the oocyte aging process. Taking these findings together, our study demonstrates that TUDCA supplementation beneficially affects the quality of aged porcine oocytes by suppressing oxidative stress, apoptosis, and endoplasmic reticulum stress. Full article

Oocyte quality is crucial for successful fertilization and subsequent embryonic development. Post-ovulatory aging leads to reduced oocyte quality and impaired embryogenesis, representing an unavoidable challenge in terms of certain assisted reproductive techniques. Diosmetin (DIOS), a natural flavonoid found in lemons, spearmint, and spider moss, exhibits antioxidant, anti-inflammatory, and anti-apoptotic properties. However, its effects on the aging of mature porcine oocytes in vitro remain unexplored. This study investigated the impact of DIOS on porcine oocyte aging. In the IVM medium, fresh oocytes were cultured for 44 h, while aging oocytes were cultured for 68 h. Following the addition of varying DIOS concentrations (0.01, 0.1, and 1 μM) to the IVM medium, the DIOS-treated aging oocyte group was cultured for 68 h. The results demonstrated that 0.1 μM DIOS significantly improved the blastocyst rates and cell counts, reduced the reactive oxygen species (ROS), elevated the glutathione (GSH) levels, enhanced the mitochondrial function, and decreased the markers of autophagy (LC3B), apoptosis (annexin V), endoplasmic reticulum stress (CHOP), and senescence (SA-β-Gal). Furthermore, DIOS treatment upregulated the expression of relevant genes compared to the aged group. These findings suggest that DIOS effectively delays porcine oocyte aging. Full article

Assisted reproduction technology (ART) procedures are often impacted by post-ovulatory aging (POA), which can lead to reduced fertilization rates and impaired embryo development. This study used RNA sequencing analysis and experimental validation to study the similarities and differences between in vivo- and vitro-matured porcine oocytes before and after POA. Differentially expressed genes (DEGs) between fresh in vivo-matured oocyte (F_vivo) and aged in vivo-matured oocyte (A_vivo) and DEGs between fresh in vitro-matured oocyte (F_vitro) and aged in vitro-matured oocyte (A_vitro) were intersected to explore the co-effects of POA. It was found that “organelles”, especially “mitochondria”, were significantly enriched Gene Ontology (GO) terms. The expression of genes related to the “electron transport chain” and “cell redox homeostasis” pathways related to mitochondrial function significantly showed low expression patterns in both A_vivo and A_vitro groups. Weighted correlation network analysis was carried out to explore gene expression modules specific to A_vivo. Trait–module association analysis showed that the red modules were most associated with in vivo aging. There are 959 genes in the red module, mainly enriched in “RNA binding”, “mRNA metabolic process”, etc., as well as in GO terms, and “spliceosome” and “nucleotide excision repair” pathways. DNAJC7, IK, and DDX18 were at the hub of the gene regulatory network. Subsequently, the functions of DDX18 and DNAJC7 were verified by knocking down their expression at the germinal vesicle (GV) and Metaphase II (MII) stages, respectively. Knockdown at the GV stage caused cell cycle disorders and increase the rate of abnormal spindle. Knockdown at the MII stage resulted in the inefficiency of the antioxidant melatonin, increasing the level of intracellular oxidative stress, and in mitochondrial dysfunction. In summary, POA affects the organelle function of oocytes. A_vivo oocytes have some unique gene expression patterns. These genes may be potential anti-aging targets. This study provides a better understanding of the detailed mechanism of POA and potential strategies for improving the success rates of assisted reproductive technologies in pigs and other mammalian species. Full article

Information on long-term effects of postovulatory oocyte aging (POA) on offspring is limited. Whether POA affects offspring by causing oxidative stress (OS) and mitochondrial damage is unknown. Here, in vivo-aged (IVA) mouse oocytes were collected 9 h after ovulation, while in vitro-aged (ITA) oocytes were obtained by culturing freshly ovulated oocytes for 9 h in media with low, moderate, or high antioxidant potential. Oocytes were fertilized in vitro and blastocysts transferred to produce F1 offspring. F1 mice were mated with naturally bred mice to generate F2 offspring. Both IVA and the ITA groups in low antioxidant medium showed significantly increased anxiety-like behavior and impaired spatial and fear learning/memory and hippocampal expression of anxiolytic and learning/memory-beneficial genes in both male and female F1 offspring. Furthermore, the aging in both groups increased OS and impaired mitochondrial function in oocytes, blastocysts, and hippocampus of F1 offspring; however, it did not affect the behavior of F2 offspring. It is concluded that POA caused OS and damaged mitochondria in aged oocytes, leading to defects in anxiety-like behavior and learning/memory of F1 offspring. Thus, POA is a crucial factor that causes psychological problems in offspring, and antioxidant measures may be taken to ameliorate the detrimental effects of POA on offspring. Full article

Postovulatory aging is known to impair the oocyte quality and embryo development due to oxidative stress in many different animal models, which reduces the success rate or pregnancy rate in human assisted reproductive technology (ART) and livestock timed artificial insemination (TAI), respectively. Salidroside (SAL), a phenylpropanoid glycoside, has been shown to exert antioxidant and antitumor effects. This study aimed to investigate whether SAL supplementation could delay the postovulatory oocyte aging process by alleviating oxidative stress. Here, we show that SAL supplementation decreases the malformation rate and recovers mitochondrial dysfunction including mitochondrial distribution, mitochondrial membrane potential (ΔΨ) and ATP content in aged oocytes. In addition, SAL treatment alleviates postovulatory aging-caused oxidative stress such as higher reactive oxygen species (ROS) level, lower glutathione (GSH) content and a reduced expression of antioxidant-related genes. Moreover, the cytoplasmic calcium ([Ca²⁺]c) and mitochondrial calcium ([Ca²⁺]mt) of SAL-treated oocytes return to normal levels. Notably, SAL suppresses the aging-induced DNA damage, early apoptosis and improves spindle assembly in aged oocytes, ultimately elevating the embryo developmental rates and embryo quality. Finally, the RNA-seq and confirmatory experience showed that SAL promotes protective autophagy in aged oocytes by activating the MAPK pathway. Taken together, our research suggests that supplementing SAL is an effective and feasible method for preventing postovulatory aging and preserving the oocyte quality, which potentially contributes to improving the successful rate of ART or TAI. Full article

The quality of oocytes determines the development potential of an embryo and is dependent on their timely fertilization after ovulation. Postovulatory oocyte aging is an inevitable factor during some assisted reproduction technology procedures, which results in poor fertilization rates and impairs embryo development. We found that fisetin, a bioactive flavonol contained in fruits and vegetables, delayed postovulatory oocyte aging in mice. Fisetin improved the development of aged oocytes after fertilization and inhibited the Sirt1 reduction in aged oocytes. Fisetin increased the GSH level and Sod2 transcription level to inhibit ROS accumulation in aged oocytes. Meanwhile, fisetin attenuated aging-induced spindle abnormalities, mitochondrial dysfunction, and apoptosis. At the molecular level, fisetin decreased aging-induced aberrant expression of H3K9me3. In addition, fisetin increased the expression levels of the mitochondrial transcription factor Tfam and the mitochondrial genes Co2 and Atp8 by upregulating Sirt1 in aged oocytes. Finally, inhibition of Sirt1 reversed the anti-aging effects of fisetin. Taken together, fisetin delayed postovulatory oocyte aging by upregulating Sirt1. Full article

The oocytes of female mammals will undergo aging after ovulation, also known as postovulatory oocyte aging (POA). Until now, the mechanisms of POA have not been fully understood. Although studies have shown that cumulus cells accelerate POA over time, the exact relationship between the two is still unclear. In the study, by employing the methods of mouse cumulus cells and oocytes transcriptome sequencing and experimental verification, we revealed the unique characteristics of cumulus cells and oocytes through ligand–receptor interactions. The results indicate that cumulus cells activated NF-κB signaling in oocytes through the IL1–IL1R1 interaction. Furthermore, it promoted mitochondrial dysfunction, excessive ROS accumulation, and increased early apoptosis, ultimately leading to a decline in the oocyte quality and the appearance of POA. Our results indicate that cumulus cells have a role in accelerating POA, and this result lays a foundation for an in-depth understanding of the molecular mechanism of POA. Moreover, it provides clues for exploring the relationship between cumulus cells and oocytes. Full article

Decrease in quality of postovulatory aged oocytes occurs due to oxidative stress and leads to low fertilization and development competence. It is one of the main causes that exerting detrimental effect on the success rate in assisted reproductive technology (ART). Auraptene (AUR), a citrus coumarin, has been reported to possess an antioxidant effects in other tissues. In this study, we aimed to confirm the potential of AUR to delay the oocyte aging process by alleviating oxidative stress. Superovulated mouse oocytes in metaphase of second meiosis (MII) were exposed to 0, 1 or 10 μM AUR for 12 h of in vitro aging. AUR addition to the culture medium recovered abnormal spindle and chromosome morphology and mitigated mitochondrial distribution and mitochondrial membrane potential (ΔΨ) in aged oocytes. AUR-treated aged oocytes also showed suppressed oxidative stress, with lower reactive oxygen species (ROS) levels, higher glutathione (GSH) levels and increased expression of several genes involved in antioxidation. Furthermore, AUR significantly elevated the fertilization and embryo developmental rates. Oocytes aged with 1 μM AUR exhibited morphokinetics that were very similar to those of the control group. Altogether, these data allowed us to conclude that AUR improved the quality of aged oocytes and suggest AUR as an effective clinical supplement candidate to prevent postovulatory aging. Full article

Postovulatory aging is a major problem that limits the success of many assisted reproductive technologies (ARTs). Oxidative stress is a leading cause of oocyte aging. This study investigated the effects of lycopene supplementation of in vitro maturation (IVM) medium during the aging of mouse oocytes on the oocytes’ morphology and oxidative stress status. Mouse cumulus-oocyte complexes (COCs) were collected and cultured in the IVM medium either for 17 h, (freshly matured oocytes), or for 48 h, (in vitro-aged oocytes), with or without lycopene. The rate of fragmented and degenerated oocytes and the oocyte levels of hydrogen peroxide (H₂O₂), malondialdehyde (MDA), total antioxidant capacity (TAC), reduced glutathione (GSH), catalase (CAT), and superoxide dismutase (SOD) were estimated and compared. Oocytes aged with 200 nM lycopene revealed significantly less fragmentation and degeneration, lower H₂O₂ and MDA levels, and higher TAC, GSH and SOD levels than those aged without lycopene. CAT levels were unchanged by lycopene treatment. Taken together, our data showed beneficial effects of lycopene during in vitro aging of mouse oocytes by reducing the oxidative stress damages that lead to their apoptosis. The present study introduces lycopene as a natural supplement to reduce the postovulatory aging-dependent abnormalities of mammalian oocytes. Full article

Postovulatory aging of the mammalian oocytes causes deterioration of oocytes through several factors including oxidative stress. Keeping that in mind, we aimed to investigate the potential of a well-known antioxidant, resveratrol (RV), to evaluate the adverse effects of postovulatory aging in porcine oocytes. After in vitro maturation (IVM), a group of (25–30) oocytes (in three replicates) were exposed to 0, 1, 2, and 4 μmol/L of RV, respectively. The results revealed that the first polar body (PB1) extrusion rate of the oocytes significantly increased when the RV concentration reached up to 2 μmol/L (p < 0.05). Considering optimum RV concentration of 2 μmol/L, the potential of RV was evaluated in oocytes aged for 24 and 48 h. We used fluorescence microscopy to detect the relative level of reactive oxygen species (ROS), while GHS contents were measured through the enzymatic method. Our results revealed that aged groups (24 h and 48 h) treated with RV (2 μmol/L) showed higher (p < 0.05) ROS fluorescence intensity than the control group, but lower (p < 0.05) than untreated aged groups. The GSH content in untreated aged groups (24 h and 48 h) was lower (p < 0.05) than RV-treated groups, but both groups showed higher levels than the control. Similarly, the relative expression of the genes involved in antioxidant activity (CAT, GPXGSH-Px, and SOD1) in RV-treated groups was lower (p < 0.05) as compared to the control group but higher than that of untreated aged groups. Moreover, the relative mRNA expression of caspase-3 and Bax in RV-treated groups was higher (p < 0.05) than the control group but lower than untreated groups. Furthermore, the expression of Bcl-2 in the RV-treated group was significantly lower than control but higher than untreated aged groups. Taken together, our findings revealed that the RV can increase the expression of antioxidant genes by decreasing the level of ROS, and its potent antiapoptotic effects resisted against the decline in mitochondrial membrane potential in aged oocytes. Full article

In regular IVF, a portion of oocytes exhibit abnormal numbers of pronuclei (PN) that is considered as abnormal fertilization, and they are routinely discarded. However, it is known that abnormal ploidy still does not completely abandon embryo development and implantation. To explore the potential of cytoplasm from those abnormally fertilized oocytes, we developed a novel technique for the transfer of large cytoplasm between pronuclear-stage mouse embryos, and assessed its impact. A large volume of cytoplast could be efficiently transferred in the PN stage using a novel two-step method of pronuclear-stage cytoplasmic transfer (PNCT). PNCT revealed the difference in the cytoplasmic function among abnormally fertilized embryos where the cytoplasm of 3PN was developmentally more competent than 1PN, and the supplementing of fresh 3PN cytoplasm restored the impaired developmental potential of postovulatory “aged” oocytes. PNCT-derived embryos harbored significantly higher mitochondrial DNA copies, ATP content, oxygen consumption rate, and total cells. The difference in cytoplasmic function between 3PN and 1PN mouse oocytes probably attributed to the proper activation via sperm and may impact subsequent epigenetic events. These results imply that PNCT may serve as a potential alternative treatment to whole egg donation for patients with age-related recurrent IVF failure. Full article

Aging is the most critical factor that influences the quality of post-ovulatory oocytes. Age-related molecular pathways remain poorly understood in fish oocytes. In this study, we examined the effect of oocyte aging on specific histone acetylation in common carp Cyprinus carpio. The capacity to progress to the larval stage in oocytes that were aged for 28 h in vivo and in vitro was evaluated. Global histone modifications and specific histone acetylation (H3K9ac, H3K14ac, H4K5ac, H4K8ac, H4K12ac, and H4K16ac) were investigated during oocyte aging. Furthermore, the activity of histone acetyltransferase (HAT) was assessed in fresh and aged oocytes. Global histone modifications did not exhibit significant alterations during 8 h of oocyte aging. Among the selected modifications, H4K12ac increased significantly at 28 h post-stripping (HPS). Although not significantly different, HAT activity exhibited an upward trend during oocyte aging. Results of our current study indicate that aging of common carp oocytes for 12 h results in complete loss of egg viability rates without any consequence in global and specific histone modifications. However, aging oocytes for 28 h led to increased H4K12ac. Thus, histone acetylation modification as a crucial epigenetic mediator may be associated with age-related defects, particularly in oocytes of a more advanced age. Full article

Fish egg quality can be markedly influenced by the oocyte age after ovulation. In this study, we examined the duration of oocyte ageing in the zebrafish (Danio rerio) and whether prolonged ageing is associated with the incidence of ploidy anomalies in the resulting embryos. Oocytes were incubated in vitro for 6 h post-stripping (HPS) at 26 °C and fertilized at 2-h intervals. Meanwhile, for eggs fertilized immediately after stripping, the fertilization, embryo survival, and hatching rates started at ~80%; these rates decreased to 39%, 24%, and 16%, respectively, for oocytes that had been stored for 4 h (p ˂ 0.05), and there was an almost complete loss of egg viability at 6 HPS. Furthermore, almost 90% of the embryos derived from 6-h aged oocytes died prior to hatching, and all larvae originating from 4- and 6-h aged oocytes showed malformations. The proportion of ploidy abnormal embryos was significantly greater at 4 HPS (18.5%) than at either 0 or 2 HPS (4.7% and 8.8%, respectively). The results revealed that zebrafish oocytes retained their fertilization potential for up to 2 h after stripping at 26 °C and indicated the contribution of post-ovulatory oocyte ageing in the occurrence of ploidy anomalies in the resulting embryos. Full article

After ovulation, mammalian oocytes will undergo a time-dependent process of aging if they are not fertilized. This postovulatory aging (POA) seriously affects the oocyte quality and then impairs the subsequent fertilization and early embryo development, which should be avoided especially in assisted reproductive technology (ART). Resveratrol is an antioxidant substance that can scavenge free radicals and is effective in improving ovary functions. Here, mouse oocytes were used to investigate the effects and mechanisms of resveratrol on POA oocytes in vitro. With 1.0 µM resveratrol treatment during aging process, the rates of fertilization and blastocyst in POA oocytes increased significantly compared with those in the POA group. Resveratrol can reduce the loss of sperm binding sites by stabilizing Juno. Resveratrol can maintain the normal morphology of spindle and mitochondrion distribution and alleviate the levels of ROS and early apoptosis. Additionally, resveratrol can reduce the changes of H3K9me2. Therefore, resveratrol can significantly improve the quality of POA oocytes in vitro to enhance the rates of fertilization and blastocyst, which may be very helpful during the ART process. Full article