Aitken R J, Harkiss D, Buckingham D W
MRC Reproductive Biology Unit, Edinburgh, Scotland.
Mol Reprod Dev. 1993 Jul;35(3):302-15. doi: 10.1002/mrd.1080350313.
The mechanisms by which ferrous ion promoters induce malondialdehyde generation by human spermatozoa have been investigated in order to provide a rational basis for the quantification and interpretation of lipid peroxidation assays. Incubation of human spermatozoa with a ferrous ion promoter in the presence of thiobarbituric acid (TBA) led to the generation of the bone fide malondialdehyde-TBA adduct. The importance of iron in the stimulation of lipid peroxidation was emphasized by the ability of Desferal and EDTA to suppress malondialdehyde generation. Paradoxically, when the concentration of EDTA relative to iron was equimolar or greater, the suppression of malondialdehyde formation was accompanied by the generation of hydroxyl radicals. These results suggested that the addition of promoter did not effect the first-chain initiation of lipid peroxidation but favored an alternative mechanism involving the catalytic decomposition of pre-existing lipid peroxides. This conclusion was reinforced by the inability of reagents that would limit the formation (superoxide dismutase and/or catalase) or availability (mannitol, formate) of hydroxyl radicals, to influence malondialdehyde generation. While hydroxyl radicals were not directly involved in Fe(2+)-promoted malondialdehyde generation, the existence of significant correlations between reactive oxygen species production and the outcome of the TBA assay, suggested that Fenton chemistry might be important in the initiation of peroxidative damage. It is proposed that the impeded propagation of peroxidation initiated by Fenton or Haber Weiss reactions would lead to the accumulation of lipid peroxides in the spermatozoa and it is these peroxides that are induced to decompose during the Fe(2+)-promoted TBA assay, stimulating a lipoperoxidative chain reaction and malondialdehyde formation.
为了为脂质过氧化测定的定量和解释提供合理依据，对亚铁离子启动剂诱导人类精子产生丙二醛的机制进行了研究。在硫代巴比妥酸（TBA）存在的情况下，将人类精子与亚铁离子启动剂一起孵育，导致了真正的丙二醛-TBA加合物的产生。去铁胺和乙二胺四乙酸（EDTA）抑制丙二醛生成的能力强调了铁在刺激脂质过氧化中的重要性。矛盾的是，当EDTA相对于铁的浓度为等摩尔或更高时，丙二醛形成的抑制伴随着羟基自由基的产生。这些结果表明，启动剂的添加并不影响脂质过氧化的第一链引发，但有利于一种涉及预先存在的脂质过氧化物催化分解的替代机制。这一结论因羟基自由基形成（超氧化物歧化酶和/或过氧化氢酶）或可用性（甘露醇、甲酸盐）受限的试剂无法影响丙二醛生成而得到加强。虽然羟基自由基不直接参与Fe(2+)促进的丙二醛生成，但活性氧产生与TBA测定结果之间存在显著相关性，这表明芬顿化学反应可能在过氧化损伤的引发中起重要作用。有人提出，由芬顿或哈伯-韦斯反应引发的过氧化传播受阻会导致精子中脂质过氧化物的积累，正是这些过氧化物在Fe(2+)促进的TBA测定过程中被诱导分解，从而刺激脂质过氧化链式反应和丙二醛的形成。
