Nicotinamide Mononucleotide Restores the Meiotic Competency of Porcine Oocytes Exposed to Ethylene Glycol Butyl Ether

ROS suppression and oocyte quality restoration: NMN intervention in decabromodiphenyl ether-exposed mice

Decabromodiphenyl ether (BDE-209) is an organic compound that is widely used in rubber, textile, electronics, plastics and other industries. It has been found that BDE-209 has a destructive effect on the reproductive system of mammals. However, the effect of BDE-209 exposure on oocyte quality and whether there is a viable salvage strategy have not been reported. Here, we report that murine oocytes exposed to BDE-209 produce a series of meiostic defects, including increased fragmentation rates and decreased PBE. Furthermore, exposure of oocytes to BDE-209 hinders mitochondrial function and disrupts mitochondrial integrity. Our observations show that supplementation with NMN successfully alleviated the meiosis impairment caused by BDE-209 and averted oocyte apoptosis by suppressing ROS generation. In conclusion, our findings suggest that NMN supplementation may be able to alleviate the oocyte quality impairment induced by BDE-209 exposure, providing a potential strategy for protecting oocytes from environmental pollutant exposure.

Supplementation with NAD+ and its precursors: A rescue of female reproductive diseases

Nicotinamide adenine dinucleotide (NAD+) is an essential coenzyme involved in many pathophysiological processes. Supplementation with NAD+ and its precursors has been demonstrated as an emerging therapeutic strategy for the diseases. NAD+ also plays an important role in the reproductive system. Here, we summarize the function of NAD+ in various reproductive diseases and review the application of NAD+ and its precursors in the preservation of reproductive capacity and the prevention of embryonic malformations. It is shown that NAD+ shows good promise as a therapeutic approach for saving reproductive capacity.

Supplementing Boar Diet with Nicotinamide Mononucleotide Improves Sperm Quality Probably through the Activation of the SIRT3 Signaling Pathway

Sperm quality is an important indicator to evaluate the reproduction ability of animals. Nicotinamide mononucleotide (NMN) participates in cell energy metabolism and reduces cell oxidative stress. However, the effect and regulatory mechanism of NMN on porcine sperm quality are still unknown. Here, 32 Landrace boars were randomly assigned to four groups (n = 8) and fed with different levels of NMN (0, 8, 16 or 32 mg/kg/d) for 9 weeks, and then serum and semen samples of the boars were collected to investigate the function and molecular mechanism of NMN in sperm quality. The results showed that the dietary NMN supplementation significantly increased sperm volume, density and motility (p < 0.05). Interestingly, NMN apparently improved the antioxidative indexes and increased the levels of testosterone (p < 0.05) in serum. Furthermore, NMN upregulated the protein levels of sirtuin 3 (SIRT3), antioxidation and oxidative phosphorylation (OXPHOS), but downregulated the protein levels of apoptosis in semen. Mechanically, NMN protected sperm from H2O2-induced oxidative stress and apoptosis through SIRT3 deacetylation. Importantly, the SIRT3-specific inhibitor 3-TYP attenuated the antioxidation and antiapoptosis of NMN in sperm. Therefore, NMN exerts antioxidation and antiapoptosis to improve boar sperm quality via the SIRT3 signaling pathway. Our findings suggest that NMN is a novel potential boar antioxidative feed additive to produce high-quality porcine semen.

Nicotinamide Mononucleotide improves oocyte maturation of mice with type 1 diabetes

BACKGROUND

The number of patients with type 1 diabetes rises rapidly around the world in recent years. Maternal diabetes has a detrimental effect on reproductive outcomes due to decreased oocyte quality. However, the strategies to improve the oocyte quality and artificial reproductive technology (ART) efficiency of infertile females suffering from diabetes have not been fully studied. In this study, we aimed to examine the effects of nicotinamide mononucleotide (NMN) on oocyte maturation of mouse with type 1 diabetes mouse and explore the underlying mechanisms of NMN's effect.

METHODS

Streptozotocin (STZ) was used to establish the mouse models with type 1 diabetes. The successful establishment of the models was confirmed by the results of body weight test, fasting blood glucose test and haematoxylin and eosin (H&E) staining. The in vitro maturation (IVM) rate of oocytes from diabetic mice was examined. Immunofluorescence staining (IF) was performed to examine the reactive oxygen species (ROS) level, spindle/chromosome structure, mitochondrial function, actin dynamics, DNA damage and histone modification of oocytes, which are potential factors affecting the oocyte quality. The quantitative reverse transcription PCR (RT-qPCR) was used to detect the mRNA levels of Sod1, Opa1, Mfn2, Drp1, Sirt1 and Sirt3 in oocytes.

RESULTS

The NMN supplementation increased the oocyte maturation rate of the mice with diabetes. Furthermore, NMN supplementation improved the oocyte quality by rescuing the actin dynamics, reversing meiotic defects, improving the mitochondrial function, reducing ROS level, suppressing DNA damage and restoring changes in histone modifications of oocytes collected from the mice with diabetes.

CONCLUSION

NMN could improve the maturation rate and quality of oocytes in STZ-induced diabetic mice, which provides a significant clue for the treatment of infertility of the patients with diabetes.

Research progress on mitochondrial damage and repairing in oocytes: A review

Oocytes are the female germ cells, which are susceptible to stress stimuli. The development of oocytes in the ovary is affected by many environmental and metabolic factors, food toxins, aging, and pathological factors. Mitochondria are the main target organelles of these factors, and the damage to mitochondrial structure and function can affect the production of ATP, the regulation of redox reactions, and apoptosis in oocytes. Mitochondrial damage is closely related to the decrease in oocyte quality and is the main factor leading to female infertility. Antioxidant foods or drugs have been used to prevent mitochondrial damage from some stressors or to repair damaged mitochondria, thereby improving oocyte development and female reproductive outcomes. In this paper, the damage of mitochondria during oocyte development by the above factors has been reviewed, and the relevant measures to alleviate the damage of mitochondria in oocytes have been discussed. Our findings may provide a theoretical basis and experimental basis for improving female fertility.

Effects of β-Nicotinamide Mononucleotide, Berberine, and Cordycepin on Lipid Droplet Content and Developmental Ability of Vitrified Bovine Oocytes

Oocyte vitrification is crucial for livestock reproduction, germplasm conservation, and human-assisted reproduction, but the overabundance of lipids is highly detrimental to oocyte development. It is necessary to reduce the lipid droplet content of oocytes before cryopreservation. This study analyzed the impact of β-nicotinamide mononucleotide (NMN), berberine (BER), or cordycepin (COR) on various aspects of bovine oocytes, including lipid droplet content and the expression levels of genes related to lipid synthesis in bovine oocytes, development ability, reactive oxygen species (ROS), apoptosis, and the expression levels of genes associated with endoplasmic reticulum (ER) stress, and mitochondrial function in vitrified bovine oocytes. The results of our study indicated that 1 μM NMN, 2.5 μM BER, and 1 μM COR were effective in reducing the lipid droplet content and suppressing the expression levels of genes involved in lipid synthesis in bovine oocytes. Our findings showed that the vitrified bovine oocytes treated with 1 μM of NMN had a significantly higher survival rate and better development ability compared to the other vitrified groups. Additionally, 1 μM NMN, 2.5 μM BER, and 1 μM COR decreased the levels of ROS and apoptosis, decreased the mRNA expression levels of genes involved in ER stress and mitochondrial fission but increased the mRNA expression levels of genes associated with mitochondrial fusion in the vitrified bovine oocytes. Our study results suggested that 1 μM NMN, 2.5 μM BER, and 1 μM COR effectively decreased the lipid droplet content and enhanced the development ability of vitrified bovine oocytes by lowering ROS levels, reducing ER stress, regulating mitochondrial function, and inhibiting apoptosis. Furthermore, the results showed that 1 μM NMN was more effective than 2.5 μM BER and 1 μM COR.

Improvement of oocyte quality through the SIRT signaling pathway

Background

Oocyte quality is one of the major deciding factors in female fertility competence.

Methods

PubMed database was searched for reviews by using the following keyword "oocyte quality" AND "Sirtuins". The methodological quality of each literature review was assessed using the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) 2020 statement.

Main Findings

Oxidative stress has been recognized as the mechanism attenuating oocyte quality. Increasing evidence from animal experiments and clinical studies has confirmed the protective roles of the sirtuin family in improving oocyte quality via an antioxidant effect.

Conclusion

The protective roles in the oocyte quality of the sirtuin family have been increasingly recognized.

Nicotinamide mononucleotide restores oxidative stress-related apoptosis of oocyte exposed to benzyl butyl phthalate in mice

Benzyl butyl phthalate (BBP) is a chemical softener and plasticizer commonly used in toys, food packaging, wallpaper, detergents and shampoos. The estrogenic actions of BBP have detrimental effects on humans and animals. In this study, the specific influence of BBP on mouse oocyte maturation was investigated using in vivo and in vitro models. The experiment first verified that BBP exposure significantly affected the rate of oocyte exclusion of the first polar body, although it did not affect germinal vesicle breakdown (GVBD) through in vitro oocyte culture system. Results of in vitro fertilization show that BBP exposure affects blastocyst rate. Subsequently, the results obtained by immunofluorescence staining technology showed that oocyte spindle organization, chromosomal arrangement and the distribution of cortical actin were disrupted by BBP exposure, and led to the failure of oocyte meiotic maturation and the subsequent early embryo development. Singe-cell transcriptome analysis found that BBP exposure altered the expression levels of 588 genes, most associated with mitochondria-related oxidative stress. Further analysis demonstrated that the detrimental effects of BBP involved the disruption of mitochondrial function and oxidative stress-induced early apoptosis. Nicotinamide mononucleotide (NMN) supplementation reduced the adverse effects of BBP. Collectively, these findings revealed a mechanism of BBP-induced toxicity on female reproduction and showed that NMN provides an effective treatment for BBP actions.

Administration of nicotinamide mononucleotide improves oocyte quality of obese mice

Objectives

Obesity has become a common health concern around the world. Maternal obesity could cause poor reproductive outcomes due to chronic ovarian inflammation and decreased oocyte quality. However, the strategies to improve the poor reproductive outcomes of obese females have not been fully studied. In this study, we aimed to explore the effects and underlying mechanisms of nicotinamide mononucleotide (NMN) on oocyte quality and reproductive performance of obese mice.

Materials and Methods

The obese mouse model was established by feeding high‐fat diet which was confirmed by body weight record, fasting blood glucose test and oral glucose tolerance test. The expression of ovary development related genes and inflammation related genes, including Lhx8, Bmp4, Adgre1, Ccl2, TNF‐α, Gal‐3, Clec10a and IL‐10 in ovaries and the expression of Bax and Sod1 in oocytes were detected using quantitative reverse transcription PCR (RT‐qPCR). The adipose size of abdominal fat tissue was determined with haematoxylin and eosin (H&E) staining. Immunofluorescence staining was performed to measure the ROS level, spindle/chromosome structure, mitochondrial function, actin dynamics and DNA damage of oocytes.

Results

The administration of NMN restored ovarian weight and reduced the adipose size of abdominal fat tissue and ovarian inflammation in high fat diet (HFD) mice. Furthermore, NMN treatment improved the oocytes quality partially by restoring the mitochondrial function and actin dynamics, reducing meiotic defects, DNA damage and ROS level and lipid droplet distribution of oocytes in HFD mice. On the long‐term effect, NMN restored offspring body weight of HFD mice.

Conclusion

NMN could improve the oocyte quality of HFD‐induced obese mice.

Nicotinamide mononucleotide supplementation improves the quality of porcine oocytes under heat stress

Background

Elevated ambient temperature-caused heat stress is a major concern for livestock production due to its negative impact on animal feed intake, growth, reproduction, and health. Particularly, the germ cells are extremely sensitive to the heat stress. However, the effective approach and strategy regarding how to protect mammalian oocytes from heat stress-induced defects have not been determined.

Methods

Germinal vesicle (GV) porcine oocytes were cultured at 41.5 °C for 24 h to induce heat stress, and then cultured at 38.5 °C to the specific developmental stage for subsequent analysis. Nicotinamide mononucleotide (NMN) was dissolved in water to 1 mol/L for a stock solution and further diluted with the maturation medium to the final concentrations of 10 μmol/L, 20 μmol/L, 50 μmol/L or 100 μmol/L, respectively, during heat stress. Immunostaining and fluorescence intensity quantification were applied to assess the effects of heat stress and NMN supplementation on the key processes during the oocyte meiotic maturation.

Results

Here, we report that NMN supplementation improves the quality of porcine oocytes under heat stress. Specifically, we found that heat stress resulted in oocyte maturation failure by disturbing the dynamics of meiotic organelles, including the cytoskeleton assembly, cortical granule distribution and mitochondrial function. In addition, heat stress induced the production of excessive reactive oxygen species (ROS) and DNA damage, leading to the occurrence of apoptosis in oocytes and subsequent embryonic development arrest. More importantly, we validated that supplementation of NMN during heat stress restored the meiotic defects during porcine oocyte maturation.

Conclusions

Taken together, our study documents that NMN supplementation is an effective approach to improve the quality of oocytes under heat stress by promoting both nuclear and cytoplasmic maturation.

Pterostilbene Alleviates Chlorpyrifos-Induced Damage During Porcine Oocyte Maturation

Chlorpyrifos (CPF), a widely used organophosphate pesticide, is reported to severely impair mammalian reproductive system. Pterostilbene (PTS), an effective free radical scavenger, is considered as beneficial for mammalian reproduction. However, the toxicity of CPF on oocyte maturation and whether PTS can eliminate the detrimental effect of CPF on oocytes remain unclear. Here, porcine oocytes were applied to investigate the potential effect and possible mechanism of CPF and PTS during oocyte maturation. This work demonstrated that CPF significantly delayed the meiotic progression and decreased the polar body extrusion by disturbing spindle assembly and chromosome alignment and causing DNA damage in oocytes (p < 0.05). And, CPF significantly impaired oocyte cytoplasmic maturation by inducing the high level of reactive oxygen species and decreasing glutathione content (p < 0.05). Moreover, CPF significantly triggered embryo apoptosis and reduced the blastocyst rate and cell number following parthenogenetic activation (p < 0.05). Whereas CPF-exposed oocytes were treated with PTS, these defects caused by CPF were obviously rescued, and oocyte maturation and subsequent embryonic development were also significantly ameliorated (p < 0.05). In conclusion, these results revealed that CPF exerted the toxic effect on porcine oocytes, while PTS effectively alleviated CPF-induced damage on oocytes. This work provides a potential strategy to protect oocyte maturation in mammalian species.

Exposure to Copper Compromises the Maturational Competency of Porcine Oocytes by Impairing Mitochondrial Function

Copper (Cu) is an essential trace element for animals, and also an important nutritional component for the normal physiology and metabolism of animal reproductive systems. An excess or lack of Cu will directly or indirectly affect animal reproductive activities. However, the effect of Cu, in particular excessive Cu, on the reproductive performance of sows has not been studied. Here, we report that excessive Cu had negative effects on oocyte maturation and organelle functions. We showed that Cu exposure perturbed porcine oocyte meiotic maturation and impaired spindle/chromosome structure, resulting in a defective spindle assembly, as well as the abnormal distribution of actin dynamics and cortical granules. In addition, single-cell transcriptome analysis identified the target effectors of Cu actions in porcine oocytes, further demonstrating that Cu exposure affects the mitochondrial distribution and function, leading to the high levels of reactive oxygen species, DNA damage, and early apoptosis of porcine oocytes. These findings demonstrate that Cu exposure causes abnormalities in the mitochondrial distribution and function, resulting in the increased oxidative stress and levels of reactive oxygen species, DNA damage, and apoptosis, ultimately leading to a decreased porcine oocyte quality.