Melatonin protects porcine oocyte from copper exposure potentially by reducing oxidative stress potentially through the Nrf2 pathway

The protective role of quercetin against copper-induced female reproductive toxicity: Insights from transcriptome analysis

Quercetin has been shown to mitigate the cytotoxic effects of heavy metals. While copper is an essential trace element for bodily functions, excessive intake has been linked to impaired female reproductive function. Transcriptome analysis was employed to identify genes that are differentially expressed in response to high copper and were validated through qRT-PCR and western blotting. ATP content and Tunel were used to identify the damage of mitochondrial and cell apoptosis. PPI analysis revealed that MKI67, TOPII, ASPM, CASP3, PLK1, and TTK are central proteins within the network. Additionally, exposure to elevated levels of copper resulted in the dysregulation of 86 genes associated with mitochondria. Conversely, treatment with quercetin (QUE) in combination with high copper led to the normalization of 42 mitochondria-related genes previously affected by high copper levels. Furthermore, CuSO4 decreases ATP content and induces cell apoptosis, which can be reversed by QUE. Results suggest that elevated copper levels could lead to oxidative stress and apoptosis by inducing mitochondrial damage, while QUE has the potential to mitigate these effects, ultimately safeguarding granulosa cells and halting the progression of cell death. This study provides novel insights into the molecular pathways involved in female reproductive toxicity caused by excessive copper exposure.

Oocyte maturation, blastocyst and embryonic development are mediated and enhanced via hormesis

The present paper provides the first integrative assessment of the capacity of dietary, endogenous and other agents to induce hormetic dose responses in oocytes, their supportive cells such as granulosa cells, blastocyst formation and early stage embryo development with the goal of improving fertility and reproductive success. The analysis showed that numerous agents enhance oocyte maturation and blastocyst/embryonic development in an hormetic fashion. These findings indicate that numerous agents improve oocyte-related biological functioning under normal conditions as well as enhancing its capacity to prevent damage from numerous chemical toxins and related stressor agents, including heat and age-related processes in pre-post conditioning and concurrent exposures. The present assessment suggests that hormetic-based lifestyles and dietary interventions may offer the potential to enhance healthy reproductive performance with applications to animal husbandry and human biology. The present findings also significantly extend the generality of the hormesis dose response concept to multiple fundamental biological processes (i.e., oocyte maturation, fertilization and blastocyst/embryo development).

Oleanolic acid promotes porcine oocyte maturation by activating the Nrf2/HO-1 signalling pathway

This study investigated the potential role and underlying mechanisms of oleanolic acid (OA), a pentacyclic triterpene with antioxidant and anti-inflammatory properties, in porcine oocytes during in vitro maturation (IVM). The results showed that supplementation with 5 μM OA during IVM resulted in a greater percentage of mature oocytes, parthenogenetically activated embryos and somatic cell nuclear-transferred embryos. This was evidenced by significant increases in the rate of first polar body expulsion, the expansion of cumulus granulosa cells and the total cell number in blastocysts. Further analysis revealed that OA promoted fatty acid accumulation and upregulated the mRNA expression of genes involved in fatty acid β-oxidation. OA significantly increased the intracellular mitochondrial membrane potential and ATP levels and effectively inhibited BAX/BCL2 and Cleaved Caspase3 protein expression. Notably, OA increased the protein levels of intracellular Nrf2 and HO-1, and the GSH levels and the activities of the antioxidant enzymes SOD and catalase (CAT), while reducing ROS levels. Mechanistically, OA activated the Nrf2/HO-1 signalling pathway, which is crucial for regulating the expression of antioxidant-related targets in IVM porcine oocytes. Our findings indicated that OA improved antioxidant capacity by activating the Nrf2/HO-1 signalling pathway, thereby promoting porcine oocyte maturation.

Melatonin in animal husbandry: functions and applications

Melatonin (N-acetyl-5-methoxytryptamine) is an essential small molecule with diverse biological functions. It plays several key roles, including regulating the secretion of reproductive hormones and the reproductive cycle, enhancing the functionality of reproductive organs, improving the quality of sperm and eggs, and mitigating oxidative stress in the reproductive system. Melatonin effectively inhibits and scavenges excess free radicals while activating the antioxidant enzyme system and reduces the production of inflammatory factors and alleviates tissue damage caused by inflammation by regulating inflammatory pathways. Additionally, melatonin contributes to repairing the intestinal barrier and regulating the gut microbiota, thereby reducing bacterial and toxin permeation. The use of melatonin as an endogenous hormone in animal husbandry has garnered considerable attention because of its positive effects on animal production performance, reproductive outcomes, stress adaptation, disease treatment, and environmental sustainability. This review explores the characteristics and biological functions of melatonin, along with its current applications in animal production. Our findings may serve as a reference for the use of melatonin in animal farming and future developmental directions.

In Vivo-Matured Oocyte Resists Post-Ovulatory Aging through the Hub Genes DDX18 and DNAJC7 in Pigs

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.

Ovarian aging: energy metabolism of oocytes

In women who are getting older, the quantity and quality of their follicles or oocytes and decline. This is characterized by decreased ovarian reserve function (DOR), fewer remaining oocytes, and lower quality oocytes. As more women choose to delay childbirth, the decline in fertility associated with age has become a significant concern for modern women. The decline in oocyte quality is a key indicator of ovarian aging. Many studies suggest that age-related changes in oocyte energy metabolism may impact oocyte quality. Changes in oocyte energy metabolism affect adenosine 5'-triphosphate (ATP) production, but how related products and proteins influence oocyte quality remains largely unknown. This review focuses on oocyte metabolism in age-related ovarian aging and its potential impact on oocyte quality, as well as therapeutic strategies that may partially influence oocyte metabolism. This research aims to enhance our understanding of age-related changes in oocyte energy metabolism, and the identification of biomarkers and treatment methods.

Melatonin-mediated actions and circadian functions that improve implantation, fetal health and pregnancy outcome

This review summarizes data related to the potential importance of the ubiquitously functioning antioxidant, melatonin, in resisting oxidative stress and protecting against common pathophysiological disorders that accompany implantation, gestation and fetal development. Melatonin from the maternal pineal gland, but also trophoblasts in the placenta, perhaps in the mitochondria, produce this molecule as a hedge against impairment of the uteroplacental unit. We also discuss the role of circadian disruption on reproductive disorders of pregnancy. The common disorders of pregnancy, i.e., stillborn fetus, recurrent fetal loss, preeclampsia, fetal growth retardation, premature delivery, and fetal teratology are all conditions in which elevated oxidative stress plays a role and experimental supplementation with melatonin has been shown to reduce the frequency or severity of these conditions. Moreover, circadian disruption often occurs during pregnancy and has a negative impact on fetal health; conversely, melatonin has circadian rhythm synchronizing actions to overcome the consequences of chronodisruption which often appear postnatally. In view of the extensive findings supporting the ability of melatonin, an endogenously-produced and non-toxic molecule, to protect against experimental placental, fetal, and maternal pathologies, it should be given serious consideration as a supplement to forestall the disorders of pregnancy. Until recently, the collective idea was that melatonin supplements should be avoided during pregnancy. The data summarized herein suggests otherwise. The current findings coupled with the evidence, published elsewhere, showing that melatonin is highly protective of the fertilized oocyte from oxidative damage argues in favor of its use for improving pregnancy outcome generally.

NRF2 attenuation aggravates detrimental consequences of metabolic stress on cultured porcine parthenote embryos

The nuclear factor erythroid 2-related factor 2 (NRF2) is a crucial transcription factor that plays a central role in regulating oxidative stress pathways by binding antioxidant response elements, but its involvement in early embryo development remains largely unexplored. In this study, we demonstrated that NRF2 mRNA is expressed in porcine embryos from day 2 to day 7 of development, showing a decrease in abundance from day 2 to day 3, followed by an increase on day 5 and day 7. Comparable levels of NRF2 mRNA were observed between early-cleaving and more developmental competent embryos and late-cleaving and less developmental competent embryos on day 4 and day 5 of culture. Attenuation of NRF2 mRNA significantly decreased development of parthenote embryos to the blastocyst stage. When NRF2-attenuated embryos were cultured in presence of 3.5 mM or 7 mM glucose, development to the blastocyst stage was dramatically decreased in comparison to the control group (15.9% vs. 27.8% for 3.5 mM glucose, and 5.4% vs. 25.3% for 7 mM glucose). Supplementation of melatonin moderately improved the development of NRF2-attenuated embryos cultured in presence of 0.6 mM glucose. These findings highlight the importance of NRF2 in early embryo development, particularly in embryos cultured under metabolically stressful conditions.

Inhibition of FSP1 impairs early embryo developmental competence in pigs

Ferroptosis suppressor protein 1 (FSP1) is a glutathione-independent ferroptosis inhibitory factor. FSP1 has been found to play a crucial role in the regulation of mitochondrial function and ferroptosis. However, its function in porcine early embryonic development remains unknown. In the present research, we found that FSP1 was expressed at different stages during porcine early embryo development. Compared with the control condition, inhibition of FSP1 reduced the cleavage rate at 24 h and 48 h and the blastocyst rate at 144 h. In addition, inhibiting FSP1 reduced the blastocyst diameter, total cell number, and proliferation capacity. Further analysis showed that inhibition of FSP1 significantly increased the levels of ferrous ions (Fe2+) and MDA but not GPX4. We also found that inhibition of FSP1 significantly decreased mitochondrial membrane potential and ATP levels, which in turn caused excessive accumulation of ROS and decreased the levels of GSH and the activity of the intracellular antioxidant enzymes SOD and CAT in embryos. In conclusion, FSP1, an important regulator, participates in regulating the development and quality of porcine early embryos. Inhibition of FSP1 impairs blastocyst formation, induces glutathione-independent ferroptosis, and further leads to oxidative stress due to mitochondrial dysfunction, ultimately affecting the developmental competence and impairing the quality of porcine early embryos.

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.

Comparing the effects of vitrification, before and after mouse oocyte in vitro maturation on developmental competence, changes in epigenetic regulators and stress oxidative response

Since the developmental stage of oocyte is a challenging issue in the success of vitrification, this study investigated the effects of vitrification, before and after in vitro maturation, on the survival and maturation rates, developmental competence and the expression levels of genes involved in apoptosis, oxidative stress and epigenetic modifications. Mouse germinal vesicle (GV) oocytes were divided into four groups: fresh in vitro matured oocytes without vitrification (fIVM), in vitro matured oocytes after vitrification (vIVM), in vitro matured oocytes before vitrification (IVMv). In addition, in vivo matured oocytes (MII) were used as control. After oocytes collection, maturation and survival rates as well as the intracellular reactive oxygen species (ROS) level were evaluated. Also, the expression level of various genes was analyzed by qRT-PCR. In addition, following artificial activation (parthenogenesis), the developmental competence of oocytes to the blastocyst stage was evaluated. A significant decrease in maturation rate and survival of vIVM oocytes was observed compared to fIVM and IVMv oocytes. Intracellular ROS levels were significantly increased in both vitrified groups compared to the fIVM group, and no significant difference between vitrified groups. Pro-apoptotic genes; BAX and Bcl2 as well as genes related to oxidative stress response Hsp1a, Hsp1b and SOD1were significantly increased in the vIVM group compared to the IVMv group. Interestingly, epigenetic regulators genes DNMT1, DNMT3a and DNMT3b were highly expressed in IVMv oocytes along with a decrease in the artificial activation rate compared to the vIVM oocytes. Our results indicated that despite observing more negative effects of vitrification before IVM on the survival rate and maturation as well as apoptosis status, less epigenetic changes in vIVM oocytes can make this process a better option in the treatment of infertility than IVM of oocytes followed by vitrification, a hypothesis that needs to be investigation in human oocytes.

The melatonin agonist ramelteon attenuates bleomycin-induced lung fibrosis by suppressing the NLRP3/TGF-Β1/HMGB1 signaling pathway

PURPOSE

The possible effects of ramelteon, a melatonin receptor agonist on bleomycin-induced lung fibrosis were analyzed via transforming growth factor β1 (TGF-β1), the high mobility group box 1 (HMGB1) and Nod-like receptor pyrin domain-containing 3 (NLRP3) which are related to the fibrosis process.

MATERIALS AND METHODS

Bleomycin (0.1 ​mL of 5 ​mg/kg) was administered by intratracheal instillation to induce pulmonary fibrosis (PF). Starting 24 ​h after bleomycin administration, a single dose of ramelteon was administered by oral gavage to the healthy groups, i.e. PF ​+ ​RM2 (pulmonary fibrosis model with bleomycin ​+ ​ramelteon at 2 ​mg/kg) and PF ​+ ​RM4 (pulmonary fibrosis model with bleomycin ​+ ​ramelteon at 4 ​mg/kg) at 2 and 4 ​mg/kg doses, respectively. Real-time polymerase chain reaction (real-time PCR) analyses, histopathological, and immunohistochemical staining were performed on lung tissues. Lung tomography images of the rats were also examined.

RESULTS

The levels of TGF-β1, HMGB1, NLRP3, and interleukin 1 beta (IL-1β) mRNA expressions increased as a result of PF and subsequently decreased with both ramelteon doses (p ​< ​0.0001). Both doses of ramelteon partially ameliorated the reduction in the peribronchovascular thickening, ground-glass appearances, and reticulations, and the loss of lung volume.

CONCLUSIONS

The severity of fibrosis decreased with ramelteon application. These effects of ramelteon may be associated with NLRP3 inflammation cascade.

Quercetin Alleviates Toxicity Induced by High Levels of Copper in Porcine Follicular Granulosa Cells by Scavenging Reactive Oxygen Species and Improving Mitochondrial Function

CuSO4 is the most commonly used feed additive in pig production at present, but long-term ingestion of excessive copper would lead to chronic copper toxicity. High copper could reduce the reproductive efficiency of sows and seriously affect the development of the pig industry. Quercetin (QUE), a powerful antioxidant, reduces toxicity of a number of heavy metals. Porcine granulosa cells (pGCs) are crucial to the fate of follicle development. The present study found that high concentrations of CuSO4 induced ROS production, which resulted in decreased mRNA expression of antioxidant-related genes GPX4, CAT, and SOD2 and increased mRNA expression of SOD1, TRX, and HO-1. The protein expression of antioxidant enzymes SOD2 and HO-1 decreased. Moreover, the concentration of MDA increased, the activity of CAT decreased, and the content of GSH decreased. After high copper treatment, the mitochondrial membrane potential (MMP) was decreased and the morphological structure was changed. However, the combined treatment with Quercetin (QUE) reversed these changes, and the level of cellular oxidative stress decreased. Therefore, we conclude that high copper has oxidative toxicity to pGCs, and QUE could remove the ROS induced by high copper, protect mitochondria from oxidative stress damage, and improve the function of pGCs.

Fertility loss: negative effects of environmental toxicants on oogenesis

There has been a global decline in fertility rates, with ovulatory disorders emerging as the leading cause, contributing to a global lifetime infertility prevalence of 17.5%. Formation of the primordial follicle pool during early and further development of oocytes after puberty is crucial in determining female fertility and reproductive quality. However, the increasing exposure to environmental toxins (through occupational exposure and ubiquitous chemicals) in daily life is a growing concern; these toxins have been identified as significant risk factors for oogenesis in women. In light of this concern, this review aims to enhance our understanding of female reproductive system diseases and their implications. Specifically, we summarized and categorized the environmental toxins that can affect oogenesis. Here, we provide an overview of oogenesis, highlighting specific stages that may be susceptible to the influence of environmental toxins. Furthermore, we discuss the genetic and molecular mechanisms by which various environmental toxins, including metals, cigarette smoke, and agricultural and industrial toxins, affect female oogenesis. Raising awareness about the potential risks associated with toxin exposure is crucial. However, further research is needed to fully comprehend the mechanisms underlying these effects, including the identification of biomarkers to assess exposure levels and predict reproductive outcomes. By providing a comprehensive overview, this review aims to contribute to a better understanding of the impact of environmental toxins on female oogenesis and guide future research in this field.

Xanthoangelol promotes early embryonic development of porcine embryos by relieving endoplasmic reticulum stress and enhancing mitochondrial function

RESEARCH QUESTION

Does the addition of an antioxidant agent, xanthoangelol (XAG), to the culture medium improve in-vitro development of porcine embryos?

DESIGN

Early porcine embryos were incubated in the presence of 0.5 μmol/l XAG in in-vitro culture (IVC) media and analysed using various techniques, including immunofluorescence staining, reactive oxygen species (ROS) detection, TdT-mediated dUTP nick-end labelling (TUNEL), and reverse transcription followed by quantitative polymerase chain reaction (RT-qPCR).

RESULTS

The addition of 0.5 μmol/l XAG to IVC media increased the rate of blastocyst formation, total cell number, glutathione concentrations and proliferative capacity, while reducing reactive oxygen species concentrations, apoptosis and autophagy. In addition, upon XAG treatment, the abundance of mitochondria and mitochondrial membrane potential significantly increased (both P < 0.001), and the genes related to mitochondrial biogenesis (TFAM, NRF1 and NRF2) were significantly up-regulated (all P < 0.001). XAG treatment also significantly increased the endoplasmic reticulum abundance (P < 0.001) and reduced the concentrations of endoplasmic reticulum stress (ERS) marker GRP78 (P = 0.003) and expression of the ERS-related genes EIF2α, GRP78, CHOP, ATF6, ATF4, uXBP1 and sXBP 1 (all P < 0.001).

CONCLUSION

XAG promotes early embryonic development in porcine embryos in vitro by reducing oxidative stress, enhancing mitochondrial function and relieving ERS.

Glutathione ameliorates the meiotic defects of copper exposed ovine oocytes via inhibiting the mitochondrial dysfunctions

Regardless of the essential role of copper (Cu) in the physiological regulation process of mammalian reproduction, excessive exposure to Cu triggers the meiotic defects of porcine oocytes via compromising the mitochondrial functions. However, the connections between the excessive Cu exposure and meiotic defects of ovine oocytes have not been reported. In this study, the effect of copper sulfate (CuSO₄) exposure on the meiotic potentials of ovine oocytes was analyzed. Subsequently, the ameliorative effect of glutathione (GSH) supplementation on the meiotic defects of CuSO₄ exposed ovine oocytes was investigated. For these purposes, the in vitro maturation (IVM) of ovine cumulus oocyte complexes (COCs) was conducted in the presence of 5, 10, 20 and 40 μg/mL of CuSO₄ supplementation. Subsequently, different concentrations of GSH (2, 4 and 8 mM) were added to the IVM medium containing CuSO₄ solution. After IVM, the assay, including nuclear maturation, spindle organization, chromosome alignment, cytoskeleton assembly, cortical granule (CGs) dynamics, mitochondrial function, reactive oxygen species (ROS) generation, apoptosis, epigenetic modification and fertilization capacity of ovine oocytes were performed. The results showed that excessive Cu exposure triggered the meiotic defects of ovine oocytes via promoting the mitochondrial dysfunction related oxidative stress damage. Moreover, the GSH supplementation, not only ameliorated the decreased maturation potential and fertilization defect of CuSO₄ exposed oocytes, but inhibited the mitochondrial dysfunction related oxidative stress damage, ROS generation, apoptosis and altered H3K27me3 expression in the CuSO₄ exposed oocytes. Combined with the gene expression pattern, the finding in the present study provided fundamental bases for the ameliorative effect of GSH supplementation on the meiotic defects of CuSO₄ exposed oocytes via inhibiting the mitochondrial dysfunctions, further benefiting these potential applications of GSH supplementation in the mammalian IVM system and livestock breeding suffering from the excessive Cu exposure.