Effects Of Cadmium On Mouse Oocyte Quality And Female Fertility

Cadmium(Cd)is widely used in industrial production,easily released to the environment through industrial wastewater and waste gas,and is enriched in living organisms through the food chain.It is a highly toxic environmental pollutant to animals and humans.In recent years,the female reproductive toxicity of cadmium has gradually become a focus issue.In this study,we used an intraperitoneal injection of a 1.5 mg / kg.b.w cadmium chloride solution to establish an animal model.Use histological HE staining,in vitro maturation of oocytes,immunofluorescence staining technology,and in vitro embryo culture experiments to detect the maturation and fertilization of mouse MII oocytes,and explore the effects of cadmium exposure on oocyte quality,subsequent embryo development,and female fertility Impact.At the same time,single-cell transcriptome sequencing was performed on cadmium-treated and control MII oocytes.The differentially expressed genes were screened,and GO function enrichment and KEGG pathway analysis were performed on the obtained differential genes by means of bioinformatics.The following research results were obtained:1.Ovarian and uterine HE staining results showed that cadmium can cause increased atretic follicles in the ovary of mice,and oocyte nuclear dislocation,contraction,and expansion and collapse of the zona pellucida were observed.Endometrial wrinkles are reduced,nodules are formed,embryonic connective tissue cells,lymphocytes are increased,and myometrium(M)is significantly thickened.The results of in vitro maturation and in vitro fertilization of oocytes showed that the first polar body excretion rate of oocytes was significantly reduced after cadmium exposure(p <0.05).The results of in vitro and in vitro fertilization experiments showed that the cleavage rate and blastocyst development rate of oocytes were significantly reduced after cadmium exposure.This shows that cadmium can also affect the quality of oocytes by affecting epigenetic modifications such as DNA methylation and histone modifications in oocytes.2.We use immunofluorescence staining technology and fluorescence intensity analysis to investigate the quality of oocytes.The results showed that after cadmium treatment,the spindle morphology in oocytes was abnormal,actin caps were lost,reactive oxygen species accumulated,antioxidant glutathione decreased,mitochondrial activity decreased,causing early cell apoptosis and DNA oxidative damage.In addition,cadmium can also affect the development of embryos by affecting epigenetic modifications such as DNA methylation and histone modifications in oocytes.3.Using single-cell transcriptome sequencing technology to analyze the entire genome expression profile of mature oocytes in the cadmium-exposed group and the control group,and screen out 938 differentially expressed genes.After functionally annotating the differential genes,it was found that the differential genes were mainly on the chromosomes Enrichment in signal pathways such as assembly,cell cycle regulation,ATP synthesis,fertilization ability,histone modification,DNA methylation,and signal transduction,among the mechanisms by which cadmium affects oocyte development,fertilization ability,and subsequent embryonic development.In summary,cadmium exposure can reduce the maturation rate and fertilization rate of oocytes,and affect the oocyte meiosis process,cytoskeleton formation,anti-oxidative stress and epigenetic modification levels to reduce oocytes’ quality,and ultimately lead to reduced early embryonic development and female fertility.