Methotrexate (MTX) is an antifolate agent which is widely used in clinic for treating malignancies, rheumatoid arthritis and ectopic pregnancy. As reported, MTX has side effects on gastrointestinal system, nervous system and reproductive system, while its potential damages on oocyte quality are still unclear. It is known that oocyte quality is essential for healthy conception and the forthcoming embryo development. Thus, this work studied the effects of MTX on the oocyte quality. We established MTX model mice by single treatment with 5 mg/Kg MTX. Both morphological and molecular biology studies were performed to assess the in-vivo matured oocytes quality and to analyze the related mechanisms. The in-vivo matured oocytes from MTX-treated mice had poor in-vitro fertilization ability, and the resulting embryo formation rates and blastocyst quality were lower than the control group. We found that the in-vivo matured MTX-treated mouse oocytes displayed abnormal transcript expressions for genes of key enzymes in the folate cycles. MTX increased the rate of abnormal chromosome alignment and affected the regulation of chromosome separation via disrupting the spindle morphology and reducing the mRNA expressions of MAD2 and Sgo1. MTX reduced the DNA methylation levels in the in-vivo matured oocytes, and further studies showed that MTX altered the expressions of DNMT1 and DNMT 3b, and may also affect the levels of the methyl donor and its metabolite. MTX impaired the in-vivo matured mouse oocyte quality by disturbing folate metabolism and affecting chromosome stability and methylation modification.

中文翻译：

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甲氨蝶呤会损害体内成熟小鼠卵母细胞的质量及其可能的机制。

甲氨蝶呤（MTX）是一种抗叶酸药物，在临床上广泛用于治疗恶性肿瘤，类风湿关节炎和异位妊娠。据报道，MTX对胃肠系统，神经系统和生殖系统有副作用，而对卵母细胞质量的潜在损害尚不清楚。众所周知，卵母细胞的质量对于健康的受孕和即将到来的胚胎发育至关重要。因此，这项工作研究了MTX对卵母细胞质量的影响。我们通过用5 mg / Kg MTX单次处理建立了MTX模型小鼠。进行了形态学和分子生物学研究，以评估体内成熟卵母细胞的质量并分析相关的机制。经MTX处理的​​小鼠的体内成熟卵母细胞体外受精能力差，胚胎形成率和囊胚质量均低于对照组。我们发现，体内成熟的MTX处理的​​小鼠卵母细胞在叶酸循环中显示关键酶基因的异常转录表达。MTX通过破坏纺锤体形态并降低MAD2和Sgo1的mRNA表达来增加异常染色体比对的速率并影响染色体分离的调控。MTX降低了体内成熟卵母细胞的DNA甲基化水平，进一步的研究表明MTX改变了DNMT1和DNMT 3b的表达，也可能影响甲基供体及其代谢产物的水平。MTX通过干扰叶酸代谢并影响染色体稳定性和甲基化修饰，损害了小鼠体内成熟卵母细胞的质量。我们发现，体内成熟的MTX处理的​​小鼠卵母细胞在叶酸循环中显示关键酶基因的异常转录表达。MTX通过破坏纺锤体形态并降低MAD2和Sgo1的mRNA表达来增加异常染色体比对的速率并影响染色体分离的调控。MTX降低了体内成熟卵母细胞的DNA甲基化水平，进一步的研究表明MTX改变了DNMT1和DNMT 3b的表达，也可能影响甲基供体及其代谢产物的水平。MTX通过干扰叶酸代谢并影响染色体稳定性和甲基化修饰，损害了小鼠体内成熟卵母细胞的质量。我们发现，体内成熟的MTX处理的​​小鼠卵母细胞在叶酸循环中显示关键酶基因的异常转录表达。MTX通过破坏纺锤体形态并降低MAD2和Sgo1的mRNA表达来增加异常染色体比对的速率并影响染色体分离的调控。MTX降低了体内成熟卵母细胞的DNA甲基化水平，进一步的研究表明MTX改变了DNMT1和DNMT 3b的表达，也可能影响甲基供体及其代谢产物的水平。MTX通过干扰叶酸代谢并影响染色体稳定性和甲基化修饰，损害了小鼠体内成熟卵母细胞的质量。