ROLE OF GLUTATHIONE-PEROXIDASE IN PROTECTING MAMMALIAN SPERMATOZOA FROM LOSS OF MOTILITY CAUSED BY SPONTANEOUS LIPID-PEROXIDATION
ROLE OF GLUTATHIONE-PEROXIDASE IN PROTECTING MAMMALIAN SPERMATOZOA FROM LOSS OF MOTILITY CAUSED BY SPONTANEOUS LIPID-PEROXIDATION
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DOI：
10.1002/mrd.1120230108
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发表时间：
1989-05-01
期刊：
影响因子：
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通讯作者：
STOREY, BT
中科院分区：
文献类型：
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作者：
ALVAREZ, JG;STOREY, BT
长期以来，人们都知道小鼠和人类精子对外源性 H2O2 引起的活力丧失敏感，而兔子精子则不然。最近的研究表明，这些物种的精子活力丧失与自发脂质过氧化的程度相关。在本研究中，研究了 H2O2 对这三个物种精子中该反应的影响。在 1-5 mM H2O2 存在下，小鼠和人类精子的自发脂质过氧化速率显着增强，而兔精子的自发脂质过氧化速率不受 H2O2 影响。脂质过氧化的增强、H2O2与细胞的反应速率、精子谷胱甘肽过氧化物酶的活性和内源性谷胱甘肽含量在小鼠精子中最高，在人精子中居中，在兔精子中很低。由于内源性谷胱甘肽完全转化为 GSSG，在 H2O2 存在下，谷胱甘肽过氧化物酶会失活：没有 GSH 可以作为过氧化物酶的电子供体底物。抑制剂巯基琥珀酸使谷胱甘肽过氧化物酶失活，对小鼠和人类精子的脂质过氧化速率和活力丧失具有与 H2O2 相同的影响。这意味着 1-5 mM 的 H2O2 本身对细胞没有本质毒性。对于巯基琥珀酸，内源性谷胱甘肽在小鼠和人类精子中以谷胱甘肽的形式存在，这表明细胞内谷胱甘肽本身的氧化还原状态在保护细胞免受自发脂质过氧化方面作用不大。小鼠和人类精子的超氧化物产生率也很高。我们得出的结论是，自发脂质过氧化的关键中间体是由超氧化物引发并利用超氧化物引发的链式反应产生的脂质氢过氧化物。谷胱甘肽过氧化物酶去除这种氢过氧化物可以保护这些精子免受过氧化作用；过氧化物酶的失活使得脂质氢过氧化物增加，从而增加过氧化速率。兔精子由于超氧化物歧化酶活性高，超氧化物反应率低；缺乏内源性谷胱甘肽和低过氧化物酶活性并不影响其脂质过氧化速率。因此，这些精子不受 H2O2 或巯基琥珀酸盐的影响。这些结果使我们推测哺乳动物精子中自发脂质过氧化的机制，其中涉及脂质过氧化氢和 O2 的反应作为速率决定步骤。
Mouse and human spermatozoa, but not rabbit spermatozoa, have long been known to be sensitive to loss of motility induced by exogenous H2O2. Recent work has shown that loss of sperm motility in these species correlates with the extent of spontaneous lipid peroxidation. In this study, the effect of H2O2 on this reaction in sperm of the three species was investigated. The rate of spontaneous lipid peroxidation in mouse and human sperm is markedly enhanced in the presence of 1-5 mM H2O2, while the rate in rabbit sperm is unaffected by H2O2. The enhancement of lipid peroxidation, the rate of reaction of H2O2 with the cells, the activity of sperm glutathione peroxidase, and the endogenous glutathione content are highest in mouse sperm, intermediate in human sperm, and very low in rabbit sperm. Inactivation of glutathione peroxidase occurs in the presence of H2O2 due to complete conversion of endogenous glutathione to GSSG: No GSH is available as electron donor substrate to the peroxidase. Inactivation of glutathione peroxidase by the inhibitor mercaptosuccinate has the same effect on rate of lipid peroxidation and loss of motility in mouse and human sperm as does H2O2. This implies that H2O2 by itself at 1-5 mM is not intrinsically toxic to the cells. With mercaptosuccinate, the endogenous glutathione is present as GSH in mouse and human sperm, indicating that the redox state of intracellular glutathione by itself plays little role in protecting the cell against spontaneous lipid peroxidation. Mouse and human sperm also have high rates of superoxide production. We conclude that the key intermediate in spontaneous lipid peroxidation is lipid hydroperoxide generated by a chain reaction initiated by and utilizing superoxide. Removal of this hydroperoxide by glutathione peroxidase protects these sperm against peroxidation; inactivation of the peroxidase allows lipid hydroperoxide to increase and so increases the peroxidation rate. Rabbit sperm have low rates of superoxide reaction due to high activity of their superoxide dismutase; lack of endogenous glutathione and low peroxidase activity does not affect their rate of lipid peroxidation. As a result, these sperm are not affected by either H2O2 or mercaptosuccinate. These results lead us to postulate a mechanism for spontaneous lipid peroxidation in mammalian sperm which involves reaction of lipid hydroperoxide and O2 as the rate-determining step.