DuTeaux Shelley Brown, Berger Trish, Hess Rex A, Sartini Becky L, Miller Marion G
Department of Environmental Toxicology, University of California, Davis, California 95616, USA.
Biol Reprod. 2004 May;70(5):1518-26. doi: 10.1095/biolreprod.103.022210. Epub 2004 Jan 21.
The objective of the present study was to characterize and investigate potential mechanisms for the male reproductive toxicity of trichloroethylene (TCE). Male rats exposed to TCE in drinking water exhibited a dose-dependent decrease in the ability to fertilize oocytes from untreated females. This reduction in fertilizing ability occurred in the absence of treatment-related changes in combined testes/epididymides weight, sperm concentration, or sperm motility. In addition, flow cytometric analysis showed that there were no treatment-related differences in sperm mitochondrial membrane potential or acrosomal stability. TCE caused slight histological changes in efferent ductule epithelium, coinciding with the previously reported ductule localization of cytochrome P450 2E1. However, no alterations were noted in the testis or in any segment of the epididymis. Because there were no treatment-related changes to sperm indices and no clear pathological lesions to explain the reduced fertilization, the present study investigated TCE-mediated sperm oxidative damage. Oxidized proteins were detected by immunochemical techniques following the derivatization of sperm protein carbonyls with dinitrophenyl hydrazine. Immunochemical staining of whole, intact sperm showed the presence of halos of oxidized proteins around the head and midpiece of sperm from TCE-treated animals. The presence of oxidized sperm proteins was confirmed by Western blotting using in vitro-oxidized sperm as a positive control. Thiobarbituric acid reactive substances analyses showed a dose-dependent increase in the level of lipid peroxidation in sperm from treated animals, as well. Oxidative damage to sperm may explain the diminished fertilizing capacity of exposed animals and provide another mechanism by which TCE can adversely affect reproductive capabilities in the male.
本研究的目的是表征并探究三氯乙烯（TCE）对雄性生殖毒性的潜在机制。饮用含TCE水的雄性大鼠使未处理雌性大鼠的卵母细胞受精的能力呈剂量依赖性下降。这种受精能力的降低发生在睾丸/附睾总重量、精子浓度或精子活力未出现与处理相关变化的情况下。此外，流式细胞仪分析表明，精子线粒体膜电位或顶体稳定性在处理组之间没有差异。TCE引起输出小管上皮出现轻微的组织学变化，这与之前报道的细胞色素P450 2E1在输出小管的定位一致。然而，睾丸或附睾的任何节段均未观察到改变。由于精子指标没有与处理相关的变化，也没有明确的病理损伤来解释受精能力的降低，因此本研究调查了TCE介导的精子氧化损伤。在用二硝基苯肼将精子蛋白羰基衍生化后，通过免疫化学技术检测氧化蛋白。对完整精子进行免疫化学染色显示，来自TCE处理动物的精子头部和中段周围存在氧化蛋白晕。以体外氧化的精子作为阳性对照，通过蛋白质免疫印迹法证实了氧化精子蛋白的存在。硫代巴比妥酸反应性物质分析表明，处理动物精子中的脂质过氧化水平也呈剂量依赖性增加。精子的氧化损伤可能解释了暴露动物受精能力的下降，并为TCE对雄性生殖能力产生不利影响提供了另一种机制。
