Zhang Chuan-Xin, Cui Wei, Zhang Min, Zhang Jie, Wang Tian-Yang, Zhu Jiang, Jiao Guang-Zhong, Tan Jing-He
College of Animal Science and Veterinary Medicine, Shandong Agricultural University, Tai-an City, P. R. China.
PLoS One. 2014 Apr 2;9(4):e93446. doi: 10.1371/journal.pone.0093446. eCollection 2014.
We studied the role of the Na+/Ca2+ exchanger (NCX) in modulating oocyte postovulatory aging by observing changes in NCX contents and activities in aging mouse and rat oocytes. Whereas the NCX activity was measured by observing oocyte activation following culture with NCX inhibitor or activator, the NCX contents were determined by immunohistochemical quantification. Although NCX was active in freshly-ovulated rat oocytes recovered 13 h post hCG injection and in aged oocytes recovered 19 h post hCG in both species, it was not active in freshly-ovulated mouse oocytes. However, NCX became active when the freshly-ovulated mouse oocytes were activated with ethanol before culture. Measurement of cytoplasmic Ca2+ revealed Ca2+ increases always before NCX activation. Whereas levels of the reactive oxygen species (ROS) and the activation susceptibility increased, the density of NCX member 1 (NCX1) decreased significantly with oocyte aging in both species. While culture with H2O2 decreased the density of NCX1 significantly, culture with NaCl supplementation sustained the NCX1 density in mouse oocytes. It was concluded that (a) the NCX activity was involved in the modulation of oocyte aging and spontaneous activation; (b) ROS and Na+ regulated the NCX activity in aging oocytes by altering its density as well as functioning; and (c) cytoplasmic Ca2+ elevation was essential for NCX activation in the oocyte.
我们通过观察衰老小鼠和大鼠卵母细胞中钠钙交换体（NCX）含量及活性的变化，研究了NCX在调节卵母细胞排卵后衰老过程中的作用。NCX活性通过观察用NCX抑制剂或激活剂培养后的卵母细胞激活情况来测定，而NCX含量则通过免疫组织化学定量法来确定。尽管在注射hCG后13小时回收的新鲜排卵大鼠卵母细胞以及两种动物中注射hCG后19小时回收的衰老卵母细胞中NCX均有活性，但在新鲜排卵的小鼠卵母细胞中NCX无活性。然而，当新鲜排卵的小鼠卵母细胞在培养前用乙醇激活时，NCX变得有活性。细胞质钙离子测量显示，钙离子升高总是先于NCX激活。随着卵母细胞衰老，两种动物中活性氧（ROS）水平和激活易感性增加，而NCX成员1（NCX1）的密度显著降低。用H₂O₂培养可显著降低小鼠卵母细胞中NCX1的密度，而补充NaCl培养可维持小鼠卵母细胞中NCX1的密度。研究得出以下结论：（a）NCX活性参与了卵母细胞衰老和自发激活的调节；（b）ROS和Na⁺通过改变其密度和功能来调节衰老卵母细胞中的NCX活性；（c）细胞质钙离子升高对于卵母细胞中NCX的激活至关重要。
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