American Center for Reproductive Medicine, Cleveland Clinic, Cleveland, OH, USA.
American Center for Reproductive Medicine, Cleveland Clinic, Cleveland, OH, USA.
Free Radic Biol Med. 2020 May 20;152:375-385. doi: 10.1016/j.freeradbiomed.2020.03.008. Epub 2020 Mar 9.
Both oxidative stress (OS) and reductive stress (RS) are the two extreme facets of redox imbalance that can have deleterious effects on sperm function. However, there is a lack of information on the physiological range of oxidation-reduction potential (ORP). The aim of this study was to investigate the effect of OS and RS on functions and associated molecular changes in normal spermatozoa in order to establish the physiological range of ORP. In the current study, total and progressive motility remained unchanged in spermatozoa exposed to ORP values 0.33 and 0.72 mV/10 sperm/mL. However, a significant (P < 0.05) decline in total and progressive motility were observed at ORP values 1.48, 2.75, -11.24, -9.76 and -9.35 mV/10 sperm/mL. Sperm vitality also decreased significantly (P < 0.0001) at 2.75, -11.24 and -9.76 mV/10 sperm/mL. Spermatozoa exposed to ORP levels 2.75 and -11.24 mV/10 sperm/mL showed a significant (P < 0.01) decrease in mitochondrial membrane potential. Intracellular reactive oxygen species (iROS) production increased (P < 0.05) in spermatozoa exposed to ORP levels of 1.48 and 2.75 mV/10 sperm/mL, while iROS decreased (P < 0.05) at ORP levels -9.76 and -11.24 mV/10 sperm/mL. No significant change in sperm DNA fragmentation was noted in sperm exposed to OS/RS and the values were below the reference range (<19.25%). Western blot analysis revealed decreased expression of CV-ATPA, CIII-UQCRC2 and CIV-MTCO1 proteins at 60 and 120 min (P < 0.05) in both OS and RS conditions. This is the first study to report physiological range of ORP (between -9.76 and 1.48 mV/10 sperm/mL) and to elucidate the role of altered expression of oxidative phosphorylation (OXPHOS) complexes proteins in mediating detrimental effects of oxidative and reductive conditions on sperm functions. A decreased expression of OXPHOS proteins and associated mitochondrial dysfunction contributes to decreased sperm motility and vitality under oxidative and reductive stress.
氧化应激（OS）和还原应激（RS）都是氧化还原失衡的两个极端方面，会对精子功能产生有害影响。然而，关于氧化还原电位（ORP）的生理范围的信息还很缺乏。本研究的目的是研究 OS 和 RS 对正常精子功能和相关分子变化的影响，以确定 ORP 的生理范围。在本研究中，暴露于 ORP 值为 0.33 和 0.72 mV/10 个精子/mL 的精子的总运动和前向运动保持不变。然而，在 ORP 值为 1.48、2.75、-11.24、-9.76 和-9.35 mV/10 个精子/mL 时，总运动和前向运动显著下降（P<0.05）。精子活力也在 2.75、-11.24 和-9.76 mV/10 个精子/mL 时显著下降（P<0.0001）。暴露于 ORP 水平 2.75 和-11.24 mV/10 个精子/mL 的精子的线粒体膜电位显著下降（P<0.01）。暴露于 ORP 水平 1.48 和 2.75 mV/10 个精子/mL 的精子的细胞内活性氧物种（iROS）产生增加（P<0.05），而在 ORP 水平-9.76 和-11.24 mV/10 个精子/mL 时 iROS 减少（P<0.05）。在 OS/RS 暴露的精子中未观察到精子 DNA 碎片化的显著变化，并且值低于参考范围（<19.25%）。Western blot 分析显示，在 OS 和 RS 条件下，CV-ATPA、CIII-UQCRC2 和 CIV-MTCO1 蛋白的表达在 60 和 120 分钟时均下降（P<0.05）。这是第一项报道 ORP 的生理范围（在-9.76 和 1.48 mV/10 个精子/mL 之间）并阐明氧化磷酸化（OXPHOS）复合物蛋白表达改变在介导氧化和还原条件对精子功能的有害影响中的作用的研究。OXPHOS 蛋白表达的减少和相关的线粒体功能障碍导致在氧化和还原应激下精子运动和活力下降。
