腐胺通过线粒体相关内质网膜改善高龄卵母细胞质量OA北大核心CSTPCD

Objective:The aim of this study is to evaluate the impact of putrescine on oocyte quality in aged mice during in vitro maturation(IVM).Additionally,the effect of putrescine on mitochondria-associated endoplasmic reticulum membrane(MAM)in aged mouse oocytes will be investigated.Methods:Germinal vesical(GV)stage mouse oocytes were cultured in vitro until they reached the Meiosis(M)Ⅱ stage.The young control group consisted of 8-week-old mice,while the old control group consisted of 40-week-old mice.The old experimental group consisted of 40-week-old mouse oocytes supplemented with 0.5 mmol/L putrescine in the IVM solution.The oocyte quality was assessed by detecting the first polar body(PB1)extrusion rate,2-cell rate,blastocyst formation rate,cortical granule distribution,spindle abnormality rate,and chromosome abnormality rate of oocytes at stage M Ⅱ.Additionally,MAM in M Ⅱ-stage oocyte was observed using transmission electron microscopy,the content of key molecules for Ca2+transfer was detected by qPCR,and the Ca2+levels in mitochondria,endoplasmic reticulum,and cytoplasm were determined using Ca2+probes.Mitochondrial function was assessed by measuring mitochondrial membrane potential,ATP content,and reactive oxygen species(ROS)levels.Results:Putrescine increased the rate of PB1 extrusion(P＜0.05)and the blastocyst rate(P＜0.05)in oocytes of aged mice and significantly reduced the rate of cortical granule distribution abnormalities(P＜0.01),spindle abnormalities(P＜0.01),and chromosomal abnormalities(P＜0.05).The oocytes contained MAM structures.Putrescine prevented the shortening of MAM spacing(P＜0.001)in oocytes of aged mice and reduced the levels of key molecules for Ca2+transfer between MAM(P＜0.05).Meanwhile,putrescine improved mitochondrial function(P＜0.05)and reduced intracellular ROS levels(P＜0.001)by alleviating mitochondrial calcium overload(P＜0.001)caused by rapid Ca2+transfer between MAMs.Conclusion:The addition of putrescine to in vitro maturation cultures significantly improved the quality of oocytes of aged mice.Putrescine also alleviated mitochondrial calcium overload and improved mitochondrial function by modulating inter-MAM Ca2+transfer.