Putrescine delays postovulatory aging of mouse oocytes by upregulating PDK4 expression and improving mitochondrial activity

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.

Impact of COVID-19 on sperm quality and the prostaglandin and polyamine systems in the seminal fluid

BACKGROUND

The implications of SARS-CoV-2 infection on male fertility remain largely unknown. Besides their well-known pro- and anti-inflammatory actions, prostaglandins and polyamines are present in semen, where they play key roles in sperm quality.

OBJECTIVES

To analyze semen parameters, oxidative profile and the seminal fluid prostaglandin and polyamine systems in samples collected from individuals without coronavirus disease 2019 diagnosis and men who recovered from coronavirus disease 2019.

MATERIALS AND METHODS

This study compared semen collected from men without positive coronavirus disease 2019 diagnosis with samples obtained from individuals 1-6 months and 7-30 months post SARS-CoV-2 infection. Semen parameters, thiobarbituric acid reactive substances, cyclooxygenase 2 expression by fluorescence immunocytochemistry and immunoblotting, prostaglandin levels by enzyme immunoassay, ornithine decarboxylase activity by a radioactive assay, and polyamine and acetylated polyamine levels by thin-layer chromatography were assessed.

RESULTS

In both groups of semen samples from coronavirus disease 2019 recovered men, sperm vitality, total and progressive sperm motility, and putrescine levels were significantly decreased when compared with samples from the uninfected group. In contrast, lipid peroxidation, leukocyte-associated cyclooxygenase 2 expression, and prostaglandin D2 levels were higher in semen from coronavirus disease 2019 recovered men than in samples from uninfected individuals. While sperm concentration and morphology, ornithine decarboxylase activity, and N-acetylputrescine levels were statistically diminished in semen obtained up to 6 months after coronavirus disease 2019 recovery, these parameters remained unchanged when samples were collected 7-30 months after coronavirus disease 2019 recovery. Coronavirus disease 2019 vaccination did not show negative effects on any of the parameters evaluated.

DISCUSSION AND CONCLUSION

Our work provides insights into the detrimental impact of coronavirus disease 2019 on several sperm parameters, in some cases, even more than a year after SARS-CoV-2 infection, which would be accompanied by alterations in the seminal fluid prostaglandin and polyamine profiles. Therefore, future treatments targeting the prostaglandin and polyamine pathways in coronavirus disease 2019 recovered men could lead to a successful reinstatement of semen parameters.

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.

Electro-Metabolic Coupling of Cumulus-Oocyte Complex

Oocyte-cumulus cell interaction is essential for oocyte maturation and competence. The bidirectional crosstalk network mediated by gap junctions is fundamental for the metabolic cooperation between these cells. As cumulus cells exhibit a more glycolytic phenotype, they can provide metabolic substrates that the oocyte can use to produce ATP via oxidative phosphorylation. The impairment of mitochondrial activity plays a crucial role in ovarian aging and, thus, in fertility, determining the success or failure of assisted reproductive techniques. This review aims to deepen the knowledge about the electro-metabolic coupling of the cumulus-oocyte complex and to hypothesize a putative role of potassium channel modulators in order to improve fertility, promote intracellular Ca2+ influx, and increase the mitochondrial biogenesis and resulting ATP levels in cumulus cells.

Time elapsed between ovulation and insemination determines the quality of fertilized rat oocytes

Genetically modified rats are valuable models in human disease research. We recently developed an improved system for rat sperm cryopreservation and in vitro fertilization (IVF) that facilitates the efficient production and preservation of genetically modified rats. In the IVF procedure performed using frozen-thawed rat sperm, the IVF schedule is fixed to ensure timely hormone administration and oocyte collection. To enhance the flexibility of the IVF schedule, possible periods of postovulated rat oocytes with normal fertility and developmental abilities should be determined. Therefore, in this study, we examined the fertilization and developmental ability of incubated oocytes 1-13 h after oocyte collection at 9:00 AM. The fertilization rate decreased 7 h after oocyte collection, and abnormally fertilized oocytes appeared 10 h after oocyte collection. The developmental rate also decreased 7 h after oocyte collection; however, live pups were obtained from oocytes 12 h after oocyte collection. In summary, ovulated rat oocytes exhibited a high developmental ability after IVF for up to 4 h after oocyte collection.

The Antioxidant Salidroside Ameliorates the Quality of Postovulatory Aged Oocyte and Embryo Development in Mice

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.

Putrescine alleviates the oxidative damage of cumulus-oocyte complex via improving fatty acid oxidation

BACKGROUND

Fatty acid oxidation of cumulus-oocyte complex (COC) provides sufficient energy for oocyte maturation. But, the relationship between fatty acid oxidation and oxidative stress in aging follicles, as well as the effect of putrescine, is still unclear.

METHODS

The porcine COCs were randomly divided into four groups and cultured in in vitro maturation (IVM) medium with or without 1 mmol/L putrescine, with 50 μmol/L hydrogen peroxide (H2O2) or with 50 μmol/L H2O2 plus 1 mmol/L putrescine. Oocyte maturation was assessed by the first polar body extrusion. The expressions of genes involved in fatty acid oxidation were detected, and the mitochondrial function was analyzed by themembrane potential.

RESULTS

The maturation rate of oocyte was significantly lower in the H2O2 group when compared with the control group (P＜0.001), and putrescine significantly increased this rate in the H2O2 plus putrescine group when compared with the H2O2 group (P＜0.001). The expressions of LKB1, STRAD, ACC2, AMPKα1 and AMPKα2 mRNAs in cumulus cells (CCs) were significantly downregulated by H2O2 treatment, and partly rescued by putrescine addition (P＜0.05-0.001). However, the changes of LKB1, STRAD, ACC2, AMPKα1 and AMPKα2 mRNAs in oocytes were inapparent. The mitochondrial membrane potential of CCs in the H2O2 group was significantly lower than that in the control group, while putrescine addition significantly increased the mitochondrial membrane potential (P＜0.001).

CONCLUSION

The decrease of oocyte maturation due to oxidative stress is related with the decreased fatty acid oxidation, and putrescine may alleviate the COCs damage via improving fatty acid oxidation.

Effect of putrescine supplementation to in vitro maturation medium on embryo development and quality in cattle

This study aimed to investigate the effect of putrescine supplementation to maturation medium during in vitro embryo production in cattle on maturation and embryo development/quality. Oocytes obtained from the ovaries of Holstein cattle were used in the study. Obtained cumulus-oocyte complexes were evaluated according to morphological structure, cytoplasmic features, and cumulus cell number, and only Category-I ones were used in the study. Before the in vitro maturation step, oocytes were randomly divided into two groups. In the first group (Putrescine group, n = 159), 0.5 mM putrescine was added to the maturation medium before in vitro maturation. No addition was applied to the maturation medium of the second group (Control group, n = 149). Cumulus expansion degrees of oocytes following maturation (Grade I: poor, Grade II: partial, and Grade III: complete) were determined. In addition, the meiosis of oocytes after maturation was evaluated by differential staining. Then the oocytes were left for fertilization with sperm and finally, possible zygotes were transferred to the culture medium. After determining the developmental stages and quality of the embryos after in vitro culture, only the embryos at the blastocyst stage were stained with the differential staining method to determine the cell numbers. When the cumulus expansion degrees of the groups were evaluated, the Grade III cumulus expansion rate in the putrescine group was higher than the control group (74.21% and 60.4%; respectively) and the Grade I expansion rate (11.95% and 26.17%; respectively) was found lower (p < .05). When the resumption of meiosis was evaluated according to the cumulus expansion degrees, it was determined that the rate of resumption of meiosis increased as the cumulus expansion increased. In addition, the cleavage rates of oocytes and reaching the blastocyst in the putrescine group were found to be higher than in the control group (p < .05). Moreover, inner cell mass, trophectoderm cells, and total cell counts were found to be higher in blastocysts obtained after the putrescine supplementation to the maturation medium compared to the control group (p < .05). As a result, it was determined that the putrescine supplementation to the maturation medium during in vitro embryo production in cattle increased the degree of cumulus expansion and the rate of resumption of meiosis. In addition, putrescine supplementation was thought to increase the rate of reaching the blastocyst of oocytes due to better cell development in embryos.

PDK4 rescues high-glucose-induced senescent fibroblasts and promotes diabetic wound healing through enhancing glycolysis and regulating YAP and JNK pathway

During the process of wound healing, fibroblasts migrate to the wound site and perform essential functions in promoting cell proliferation, as well as synthesizing and secreting the extracellular matrix (ECM). However, in diabetic wounds, senescent fibroblasts exhibit impaired proliferative capacity and fail to synthesize essential ECM components. Pyruvate dehydrogenase kinase 4 (PDK4), a key enzyme regulating energy metabolism, has been implicated in modulating cellular senescence and fibroblast function. However, its specific role in diabetic wounds remains poorly understood. In this study, we conducted a series of in vivo and in vitro experiments using STZ-induced diabetic mice and human dermal fibroblasts. We evaluated cellular senescence markers, including SA-β-gal, P53, P16, P21, and PAI-1, as well as senescence-associated secretory phenotype (SASP) factors. Finally, we observed that PDK4 increased in normal wound healing, but its expression was insufficient in diabetic wounds. Significantly, the overexpression of PDK4 demonstrated the potential to accelerate diabetic wound healing and improve the senescence phenotype both in vivo and in vitro. Furthermore, our study elucidated the underlying mechanism by which PDK4 improved the senescent phenotype through the enhancement of glycolysis and regulation of YAP and JNK pathway. The effect was dependent on metabolic reprogramming and subsequent reduction of reactive oxygen species (ROS), which was mediated by PDK4. Overall, our findings highlight the potential of PDK4 as a promising therapeutic target for addressing diabetic wounds.

Essential Role of Granulosa Cell Glucose and Lipid Metabolism on Oocytes and the Potential Metabolic Imbalance in Polycystic Ovary Syndrome

Granulosa cells are crucial for the establishment and maintenance of bidirectional communication among oocytes. Various intercellular material exchange modes, including paracrine and gap junction, are used between them to achieve the efficient delivery of granulosa cell structural components, energy substrates, and signaling molecules to oocytes. Glucose metabolism and lipid metabolism are two basic energy metabolism pathways in granulosa cells; these are involved in the normal development of oocytes. Pyruvate, produced by granulosa cell glycolysis, is an important energy substrate for oocyte development. Granulosa cells regulate changes in intrafollicular hormone levels through the processing of steroid hormones to control the development process of oocytes. This article reviews the material exchange between oocytes and granulosa cells and expounds the significance of granulosa cells in the development of oocytes through both glucose metabolism and lipid metabolism. In addition, we discuss the effects of glucose and lipid metabolism on oocytes under pathological conditions and explore its relationship to polycystic ovary syndrome (PCOS). A series of changes were found in the endogenous molecules and ncRNAs that are related to glucose and lipid metabolism in granulosa cells under PCOS conditions. These findings provide a new therapeutic target for patients with PCOS; additionally, there is potential for improving the fertility of patients with PCOS and the clinical outcomes of assisted reproduction.

Novel Role of the SIRT1 in Endocrine and Metabolic Diseases

Silent information regulator 1 (SIRT1), a highly conserved NAD⁺-dependent deacetylase, is a cellular regulator that has received extensive attention in recent years and regarded as a sensor of cellular energy and metabolism. The accumulated evidence suggests that SIRT1 is involved in the development of endocrine and metabolic diseases. In a variety of organisms, SIRT1 regulates gene expression through the deacetylation of histone, transcription factors, and lysine residues of other modified proteins including several metabolic and endocrine signal transcription factors, thereby enhancing the therapeutic effects of endocrine and metabolic diseases. These evidences indicate that targeting SIRT1 has promising applications in the treatment of endocrine and metabolic diseases. This review focuses on the role of SIRT1 in endocrine and metabolic diseases. First, we describe the background and structure of SIRT1. Then, we outline the role of SIRT1 in endocrine and metabolic diseases such as hyperuricemia, diabetes, hypertension, hyperlipidemia, osteoporosis, and polycystic ovarian syndrome. Subsequently, the SIRT1 agonists and inhibitors in the above diseases are summarized and future research directions are proposed. Overall, the information presents here may highlight the potential of SIRT1 as a future biomarker and therapeutic target for endocrine and metabolic diseases.

Reprogramming of ovarian aging epigenome by resveratrol

Resveratrol is an antiaging, antioxidant, and anti-inflammatory natural polyphenolic compound. Growing evidence indicates that resveratrol has potential therapeutic effects for improving aging ovarian function. However, the mechanisms underlying prolonged reproductive longevity remain elusive. We found that resveratrol ameliorates ovarian aging transcriptome, some of which are associated with specific changes in methylome. In addition to known aging transcriptome of oocytes and granulosa cells such as decline in oxidoreductase activity, metabolism and mitochondria function, and elevated DNA damage and apoptosis, actin cytoskeleton are notably downregulated with age, and these defects are mostly rescued by resveratrol. Moreover, the aging-associated hypermethylation of actin cytoskeleton is decreased by resveratrol. In contrast, deletion of Tet2, involved in DNA demethylation, abrogates resveratrol-reprogrammed ovarian aging transcriptome. Consistently, Tet2 deficiency results in additional altered pathways as shown by increased mTOR and Wnt signaling, as well as reduced DNA repair and actin cytoskeleton with mouse age. Moreover, genes associated with oxidoreductase activity and oxidation-reduction process were hypermethylated in Tet2-deficient oocytes from middle-age mice treated with resveratrol, indicating that loss of Tet2 abolishes the antioxidant effect of resveratrol. Taking together, our finding provides a comprehensive landscape of transcriptome and epigenetic changes associated with ovarian aging that can be reprogrammed by resveratrol administration, and suggests that aberrantly increased DNA methylation by Tet2 deficiency promotes additional aging epigenome that cannot be effectively restored to younger state by resveratrol.

Quercetin protects porcine oocytes from in vitro aging by reducing oxidative stress and maintaining the mitochondrial functions

Quercetin (QUE) is a component of the flavonoid family that shows various therapeutic properties, such as antioxidant effects. However, whether QUE affects porcine oocyte in vitro aging has not yet been investigated. Therefore, in this study, we applied various doses of QUE to freshly isolated porcine oocytes and found that 10 µM QUE improved the oocyte maturation rate in vitro, as reflected by the increased degree of cumulus cell expansion and first polar body extrusion. More importantly, we found that QUE reduced in vitro aging and improved the maturity level of porcine oocytes after another 24 h of culturing, accompanied by the upregulated expression levels of bone morphogenetic protein 15, growth differentiation factor 9, Moloney sarcoma oncogene, and cyclin-dependent kinase 2. In addition, we found that QUE treatment significantly reduced the intracellular reactive oxygen species levels, apoptosis, and autophagy and upregulated the expression levels of superoxide dismutase 2 and catalase in aged porcine oocytes. In addition, QUE restored impaired mitochondrial membrane potential and spindle assembly in aged porcine oocytes. Our findings demonstrate that QUE can protect porcine oocytes from in vitro aging by reducing oxidative stress and maintaining mitochondrial function.

Effects of putrescine on the quality and epigenetic modification of mouse oocytes during in vitro maturation

CONTEXT

Low ovarian putrescine levels and decreased peak values following luteinising hormone peaks are related to poor oocyte quantity and quality in ageing women.

AIMS

To investigate the effects of putrescine supplementation in in vitro maturation (IVM) medium on oocyte quality and epigenetic modification.

METHODS

Germinal vesicle oocytes retrieved from the ovaries of 8-week-old and 9-month-old mice were divided into four groups (the young, young+difluoromethylornithine (DFMO), ageing and ageing+putrescine groups) and cultured in IVM medium with or without 1mM putrescine or DFMO for 16h. The first polar body extrusion (PBE), cleavage and embryonic development were evaluated. Spindles, chromosomes, mitochondria and reactive oxygen species (ROS) were measured. The expression levels of SIRT1, H3K9ac, H3K9me2, H3K9me3, and 5mC levels were evaluated. Sirt1 and imprinted genes were detected.

RESULTS

The PBE was higher in the ageing+putrescine group than in the ageing group. Putrescine increased the total and inner cell mass cell numbers of blastocysts in ageing oocytes. Putrescine decreased aberrant spindles and chromosome aneuploidy, increased the mitochondrial membrane potential and decreased ROS levels. Putrescine increased SIRT1 expression and attenuated the upregulation of H3K9ac levels in ageing oocytes. Putrescine did not affect 5mC, H3K9me2 or H3K9me3 levels or imprinted gene expression.

CONCLUSIONS

Putrescine supplementation during IVM improved the maturation and quality of ageing oocytes and promoted embryonic development by decreasing ROS generation, maintaining mitochondrial and spindle function and correcting aberrant epigenetic modification.

IMPLICATIONS

Putrescine shows application potential for human-assisted reproduction, especially for IVM of oocytes from ageing women.

Redox signaling at the crossroads of human health and disease

Redox biology is at the core of life sciences, accompanied by the close correlation of redox processes with biological activities. Redox homeostasis is a prerequisite for human health, in which the physiological levels of nonradical reactive oxygen species (ROS) function as the primary second messengers to modulate physiological redox signaling by orchestrating multiple redox sensors. However, excessive ROS accumulation, termed oxidative stress (OS), leads to biomolecule damage and subsequent occurrence of various diseases such as type 2 diabetes, atherosclerosis, and cancer. Herein, starting with the evolution of redox biology, we reveal the roles of ROS as multifaceted physiological modulators to mediate redox signaling and sustain redox homeostasis. In addition, we also emphasize the detailed OS mechanisms involved in the initiation and development of several important diseases. ROS as a double-edged sword in disease progression suggest two different therapeutic strategies to treat redox-relevant diseases, in which targeting ROS sources and redox-related effectors to manipulate redox homeostasis will largely promote precision medicine. Therefore, a comprehensive understanding of the redox signaling networks under physiological and pathological conditions will facilitate the development of redox medicine and benefit patients with redox-relevant diseases.

Epitalon protects against post-ovulatory aging-related damage of mouse oocytes in vitro

The developmental potential of oocytes decreases with time after ovulation in vivo or in vitro. Epitalon is a synthetic short peptide made of four amino acids (alanine, glutamic acid, aspartic acid, and glycine), based on a natural peptide called epithalamion extracted from the pineal gland. It is a potent antioxidant, comparable to melatonin, that may confer longevity benefits. The current study aims to test the protective effects of Epitalon on the quality of post-ovulatory aging oocytes. Epitalon at 0.1mM was added to the culture medium, and the quality of oocytes was evaluated at 6h, 12h, and 24h of culture. We found that 0.1mM Epitalon reduced intracellular reactive oxygen species. Epitalon treatment significantly decreased frequency of spindle defects and abnormal distribution of cortical granules during aging for 12h and 24h, while increased mitochondrial membrane potential and DNA copy number of mitochondria, thus decreasing apoptosis of oocytes by 24h of in vitro aging. Our results suggest that Epitalon can delay the aging process of oocytes in vitro via modulating mitochondrial activity and ROS levels.

Characterization of differential gene expression of broiler chicken to thermal stress in discrete developmental stages

Prolonged exposure to high temperatures is linked to a range of physiological responses in broiler chickens including reduced disease resistance, low growth rate, and high mortality rate. In this study, we investigated the effect of heat stress on gene expression levels in 4-week-old and 6-week-old chickens each exposed to environments conditioned at thermoneutral (21 °C) and high (32 °C) temperatures. The analysis of differentially expressed genes (DEGs) using microarray revealed that genes underlying reactive oxygen species (ROS) production, cell nutrient intake, glucose metabolism, and circadian rhythm were differentially regulated in association with heat stress. We also found that the deviation in expression levels across the transcriptome in response to heat stress was significantly stronger (P< 2.2×10-16) in 6-week-olds compared to younger chickens. We finally observed a significant trend (r = 0.78, P< 2.2×10-16) that genes with a higher estimate of expression in the microarray were more likely to have a higher expression level in RNA-sequencing. Together, our findings provide comprehensive insights into the physiology involved in stress responses at varying developmental stages, which may facilitate chicken breeding to maximize their productivity under adverse conditions.

In vivo and in vitro postovulatory aging: when time works against oocyte quality?

In mammalian species an optimal fertilization window during which successful fertilization occurs. In the majority of mammals estrus marks ovulation time and coincident with mating, thereby allowing the synchronized meeting in the fallopian tubes, between freshly ejaculated sperm and freshly ovulated oocytes. Conversely, women do not show natural visual signs of ovulation such that fertilization can occur hours later involving an aged oocyte and freshly ejaculated spermatozoa. During this time, the oocyte undergoes a rapid degradation known as “postovulatory aging” (POA). POA may become particularly important in the human-assisted reproductive technologies, as the fertilization of retrieved mature oocytes can be delayed due to increased laboratory workload or because of unforeseeable circumstances, like the delayed availability of semen samples. This paper is an updated review of the consequences of POA, either in vivo or in vitro, on oocyte quality with particular attention to modifications caused by POA on oocyte nuclear, cytoplasmic, genomic, and epigenetic maturation, and embryo development.

Epigenetic effect of putrescine supplementation during in vitro maturation of oocytes on offspring in mice

PURPOSE

To investigate the epigenetic safety of putrescine supplementation during in vitro maturation (IVM) to offspring.

METHODS

Germinal vesicle oocytes retrieved from 12-week-old mice were randomly divided into two groups and cultured in IVM medium with or without 1 mmol/L putrescine for 16 h. Then, in vitro fertilization and embryo transplantation were conducted to produce the F1 offspring. The F1 mated with ordinary mice and bred the F2 offspring. The DNA methylation patterns in the brain and heart of F1 were investigated by reduced representation bisulfite sequencing. Imprinted gene expression levels of F1 oocytes were tested. The global methylation of F2 was examined by dot blot.

RESULTS

The weight, organ coefficient, and histology were normal in the F1 and F2 offspring from the putrescine-treated oocytes. An overall methylation level of 31.23 to 32.53% was observed for all CpG sites in the brain and heart of the two groups. The DNA methylation patterns of the brain and heart in F1 were not altered in general, with subtle differences. The expression levels of imprinted genes including H19, Snrpn, Peg3, Igf2, and Igf2r did not statistically change. The global 5mC level of F2 was consistent with the control group.

CONCLUSION

Putrescine supplementation during IVM did not directly affect the development, health, and reproduction, and did not affect the genome and global epigenetics of mouse offspring derived from those oocytes. The transient putrescine treatment for improving oocyte maturation shows its long-term safety of genome and epigenetics in the offspring of mice.

Understanding Transcriptomic and Serological Differences between Forced Molting and Natural Molting in Laying Hens

Molting is natural adaptation to climate change in all birds, including chickens. Forced molting (FM) can rejuvenate and reactivate the reproductive potential of aged hens, but the effect of natural molting (NM) on older chickens is not clear. To explore why FM has a dramatically different effect on chickens compared with NM, the transcriptome analyses of the hypothalamus and ovary in forced molted and natural molted hens at two periods with feathers fallen and regrown were performed. Additionally, each experimental chicken was tested for serological indices. The results of serological indices showed that growth hormone, thyroid stimulating hormone, and thyroxine levels were significantly higher (p < 0.05) in forced molted hens than in natural molted hens, and calcitonin concentrations were lower in the forced molted than in the natural molted hens. Furthermore, the transcriptomic analysis revealed a large number of genes related to disease resistance and anti-aging in the two different FM and NM periods. These regulatory genes and serological indices promote reproductive function during FM. This study systematically revealed the transcriptomic and serological differences between FM and NM, which could broaden our understanding of aging, rejuvenation, egg production, and welfare issues related to FM in chickens.

Sorbitol accumulation decreases oocyte quality in aged mice by altering the intracellular redox balance

Sorbitol is a product of glucose metabolism through the polyol pathway. Many studies have demonstrated that excessive sorbitol can disrupt the intracellular redox balance. However, we still know very little about the impact of excessive intracellular sorbitol on oocyte quality, oocyte maturation, and embryo developmental potential. This study explored whether intracellular sorbitol accumulates in the oocytes of aged mice during in vitro maturation (IVM) and what roles sorbitol plays in oocyte development and maturation. Our results showed that sorbitol levels were significantly higher in in vitro-matured oocytes from aged mice than in oocytes from young mice (14.08 ± 3.78 vs. 0.23 ± 0.04 ng/oocyte). The expression of aldose reductase (AR) mRNA was significantly higher in the in vitro-cultured oocytes from 9-month-old mice than prior to culture. To decrease the excessive intracellular sorbitol in oocytes from aged mice, sorbinil, a specific inhibitor of aldose reductase, was supplemented in IVM medium, and the sorbitol level was significantly decreased (14.08 ± 3.78 vs. 0.48 ± 0.19 ng/oocyte). Our results indicated that the percentage of oocytes with first polar body extrusion (PBE) was significantly higher in the sorbinil group than in the aged group (82.4% ± 7.2% vs. 66.1% ± 6.9%), and the content of sorbitol was drastically increased in the aged group. The ROS fluorescence intensity in the sorbinil group was drastically lower than that in the aged group, while the GSH fluorescence intensity was significantly higher. Interestingly, SOD1 was upregulated in the sorbinil group. The present study suggests that excessive sorbitol accumulation is induced during IVM in aged mouse oocytes, which negatively influences oocyte quality by altering the intracellular redox balance. Inhibition of sorbitol accumulation may be a potential method to improve the nuclear maturation of aged oocytes.

Nampt affects mitochondrial function in aged oocytes by mediating the downstream effector FoxO3a

Maternal aging can impair the quality and decrease the developmental competence of ovulated oocytes. In this study, compromised germinal vesicle breakdown (GVBD) was found in aged mice oocytes. Furthermore, we observed increased reactive oxygen species (ROS) and mitochondrial Ca²⁺ levels, along with reduced mitochondrial temperature in aged oocytes. Maternal aging also changed the crotonylation level in oocytes. Forkhead box O3 (FoxO3a), a member of the forkhead protein family involved in the regulation of cell survival and life span reached a peak level in the metaphase II stage. Compared with a younger group, FoxO3a expression increased in aged oocytes. Intracellular localization of FoxO3a changed from the cytoplasm to chromatin in response to aging. The expression of the upstream regulator nicotinamide-phosphoribosyltransferase (Nampt) peaked in the GVBD stage. Moreover, Nampt expression was increased in aged oocytes, and more intense staining of Nampt was found in aged mice ovary. To further study the role of Nampt in mitochondrial function, specific agonist P7C3 and inhibitor FK866 were applied to aged oocytes, and FK866 significantly decreased adenosine triphosphate and mitochondrial membrane potential. In conclusion, mitochondrial dysfunction in aged oocytes was associated with elevated FoxO3a, and suppression of Nampt could further impair mitochondrial function.

Heliotropium indicum L.: From Farm to a Source of Bioactive Compounds with Therapeutic Activity

This study aimed to summarize the available data on the ethnomedicinal and phytopharmacological activities of Heliotropium indicum L. based on database reports. For this purpose, an up-to-date literature search was carried out in the Google Scholar, Scopus, Springer Link, Web of Science, ScienceDirect, ResearchGate, PubMed, Chem Spider, Elsevier, BioMed Central, and patent offices (e.g., USPTO, CIPO, NPI, Google patents, and Espacenet) for the published materials. The findings suggest that the plant contains many important phytochemicals, including pyrrolizidine alkaloids, indicine, echinitine, supinine, heleurine, heliotrine, lasiocarpine, acetyl indicine, indicinine, indicine N-oxide, cynoglossine, europine N-oxide, heleurine N-oxide, heliotridine N-oxide, heliotrine N-oxide, heliotrine, volatile oils, triterpenes, amines, and sterols. Scientific reports revealed that the herb showed antioxidant, analgesic, antimicrobial, anticancer, antituberculosis, antiplasmodial, anticataract, antifertility, wound healing, antiinflammatory, antinociceptive, antihyperglycemic, anthelmintic, diuretic, antitussive, antiglaucoma, antiallergic, and larvicidal activity. In conclusion, in vitro studies with animal models seem to show the potential beneficial effects of H. indicum against a wide variety of disorders and as a source of phytotherapeutic compounds. However, clinical studies are necessary to confirm the effects observed in animal models, determine the toxicity of the therapeutic dose and isolate the truly bioactive components.

Perfluorooctanoic acid inhibits the maturation rate of mouse oocytes cultured in vitro by triggering mitochondrial and DNA damage

BACKGROUND

Perfluorooctanoic acid (PFOA) is widely used in the manufacture of household and industrial products. It has certain toxicity and leaves many residues in the environment. Numerous studies have shown that PFOA exhibits endocrine disrupting properties and immunotoxicity and induces developmental defects. However, there is very little information regarding its toxicity on oocytes.

METHODS

We cultured denuded oocytes in maturation medium supplemented with 0, 300, or 500 PFOA during IVM and evaluated the maturation of oocytes from the aspects of ROS(DCFH-DA), mitochondria(MitoOrange and JC-1), DNA damage(P-H2AX), and cytoskeleton(β-tubulin).

RESULTS

Compared with the control group, the PFOA treatment group exhibited significantly reduced proportion of oocytes matutation. Furthermore, the DCFH-DA test showed that PFOA significantly increased reactive oxygen species (ROS) levels. PFOA disrupted mitochondrial distribution and decreased mitochondrial function as assessed using MitoOrange and JC-1. In addition, PFOA-treated oocytes exhibited a significantly higher percentage of P-H2AX, defective β-tubulin, abnormal chromosome alignment, lower expression of the anti-apoptotic gene Bcl-2, and higher expression of the apoptotic genes caspase3 and Bax.

CONCLUSION

In summary, PFOA could negatively and directly affect oocyte maturation in vitro and cause oxidative stress, mitochondrial function disruption, DNA damage, cytoskeleton damage, and apoptosis.

Reprogramming of glucose metabolism of cumulus cells and oocytes and its therapeutic significance

The aim of this review is to summarize our current understanding of the molecular mechanism for the glucose metabolism, especially pyruvate dehydrogenase (PDH), during oocyte maturation, as well as future perspectives of therapeutic strategies for aging focusing on metabolic regulation between aerobic glycolysis and the tricarboxylic acid (TCA) cycle/oxidative phosphorylation (OXPHOS). Each keyword alone or in combination was used to search from PubMed. Glucose metabolism is a dynamic process involving "On" and "Off" switches by the pyruvate dehydrogenase kinase (PDK)-PDH axis, which is crucial for energy metabolism and mitochondrial efficiency in cumulus cell differentiation and oocyte maturation. Activation of PDK suppresses the conversion of pyruvate to acetyl-coenzyme A (acetyl-CoA) through the inactivation of PDH, which allows the cumulus cells to supply sufficient amounts of pyruvate, lactate, and nicotinamide adenine dinucleotide phosphate (NADPH) to the oocytes. On the other hand, inactivation of PDK in oocytes can produce adenosine triphosphate (ATP) through a metabolic shift from aerobic glycolysis to the TCA cycle/OXPHOS. The metabolic balance between aerobic glycolysis and TCA cycle/OXPHOS presents us with a number of enzymes, ligands, receptors, and antioxidants that are potential therapeutic targets, some of which have already been successfully pursued to improve fertility outcomes. However, there are also many reports that question their efficacy. In conclusion, understanding the molecular mechanisms involved in the PDK-PDH axis is a crucial step to advance in novel therapeutic strategies to improve oocyte quality.

microRNA-9-5p regulates the mitochondrial function of hepatocellular carcinoma cells through suppressing PDK4

Due to the lack of early diagnostic and effective treatment modalities, hepatocellular carcinoma (HCC) is still the most lethal cancer with a high mortality on a global scale. Recent studies have highlighted the key roles of microRNAs (miRs) in HCC development. In the study, we attempted to investigate the potential role of miR-9-5p in the progression of HCC. Expression of pyruvate dehydrogenase kinase 4 (PDK4) and miR-9-5p was examined in HCC tissues collected from HCC patients and cell lines. The proliferation, migration, invasion, and apoptosis of HCC cells, and levels of oxygen consumption rate, extracellular acidification rate and reactive oxygen species (ROS) as well as the tumorigenicity of transfected cells in vivo were measured after gain- and loss-of-function experiments in HCC cells. It was revealed that miR-9-5p was upregulated, while PDK4 was poorly expressed in HCC tissues and cells, associating with a poor prognosis of HCC patients. miR-9-5p directly targeted PDK4 and could downregulate its expression, thus leading to promoted cell proliferation, invasion and migration, enhanced mitochondrial activity and energy metabolism, and suppressed apoptosis in HCC cells, along with increased tumorigenicity in mouse xenograft models. Altogether, miR-9-5p facilitated mitochondrial energy metabolism of HCC cells by downregulating PDK4, promoting the development of HCC. miR-9-5p and PDK4 may serve as potential therapeutic targets for preventing recurrence and metastasis of HCC.

Clinical Application of Antioxidants to Improve Human Oocyte Mitochondrial Function: A Review

Mitochondria produce adenosine triphosphate (ATP) while also generating high amounts of reactive oxygen species (ROS) derived from oxygen metabolism. ROS are small but highly reactive molecules that can be detrimental if unregulated. While normally functioning mitochondria produce molecules that counteract ROS production, an imbalance between the amount of ROS produced in the mitochondria and the capacity of the cell to counteract them leads to oxidative stress and ultimately to mitochondrial dysfunction. This dysfunction impairs cellular functions through reduced ATP output and/or increased oxidative stress. Mitochondrial dysfunction may also lead to poor oocyte quality and embryo development, ultimately affecting pregnancy outcomes. Improving mitochondrial function through antioxidant supplementation may enhance reproductive performance. Recent studies suggest that antioxidants may treat infertility by restoring mitochondrial function and promoting mitochondrial biogenesis. However, further randomized, controlled trials are needed to determine their clinical efficacy. In this review, we discuss the use of resveratrol, coenzyme-Q10, melatonin, folic acid, and several vitamins as antioxidant treatments to improve human oocyte and embryo quality, focusing on the mitochondria as their main hypothetical target. However, this mechanism of action has not yet been demonstrated in the human oocyte, which highlights the need for further studies in this field.

Isosteviol sodium protects the cardiomyocyte response associated with the SIRT1/PGC-1α pathway

Cardiomyocyte dysfunction is attributed to excess oxidative damage, but the molecular pathways involved in this process have not been completely elucidated. Evidence indicates that isosteviol sodium (STVNa) has cardioprotective effects. We therefore aimed to identify the effect of STVNa on cardiomyocytes, as well as the potential mechanisms involved in this process. We established two myocardial hypertrophy models by treating H9c2 cells with high glucose (HG) and isoprenaline (ISO). Our results showed that STVNa reduced H9c2 mitochondrial damage by attenuating oxidative damage and altering the morphology of mitochondria. The results also indicated that STVNa had a positive effect on HG- and ISO-induced damages via mitochondrial biogenesis. The protective effects of STVNa on cardiomyocytes were associated with the regulation of the SIRT1/PGC-1α signalling pathway. Importantly, the effects of STVNa involved different methods of regulation in the two models, which was confirmed by experiments using an inhibitor and activator of SIRT1. Together, the results provide the basis for using STVNa as a therapy for the prevention of cardiomyocyte dysfunctions.