Bailey Denise C, Todt Callie E, Orfield Sarah E, Denney Rachel D, Snapp Isaac B, Negga Rekek, Montgomery Kara M, Bailey Andrew C, Pressley Aireal S, Traynor Wendy L, Fitsanakis Vanessa A
King University, Department of Biology, 1350 King College Road, Bristol, TN 37620, USA.
King University, Department of Mathematics and Physics, 1350 King College Road, Bristol, TN 37620, USA.
Neurotoxicology. 2016 Sep;56:170-179. doi: 10.1016/j.neuro.2016.07.011. Epub 2016 Aug 5.
Reports have linked human exposure to Mn/Zn ethylene-bis-dithiocarbamate (Mn/Zn-EBDC) fungicides with multiple pathologies, from dermatitis to central nervous system dysfunction. Although members of this family of agrochemicals have been available for over 50 years, their mechanism of toxicity in humans is still unclear. Since mitochondrial inhibition and oxidative stress are implicated in a wide variety of diseases, we hypothesized that Caenorhabditis elegans (C. elegans) exposed to a commercially-available formulation of an Mn/Zn-EBDC-containing fungicide (Manzate; MZ) would also show these endpoints. Thus, worms were treated chronically (24h) with various MZ concentrations and assayed for reduced mitochondrial function and increased levels of reactive oxygen species (ROS). Oxygen consumption studies suggested Complex I inhibition in all treatment groups compared to controls (p<0.01). In order to verify these findings, assays specific for Complex II or Complex IV activity were also completed. Data analysis from these studies indicated that neither complex was adversely affected by MZ treatment. Additional data from ATP assays indicated a statistically significant decrease (p<0.001) in ATP levels in all treatment groups when compared to control worms. Further studies were completed to determine if exposure of C. elegans to MZ also resulted in increased ROS concentrations. Studies demonstrated that hydrogen peroxide, but not superoxide or hydroxyl radical, levels were statistically significantly increased (*p<0.05). Since hydrogen peroxide is known to up-regulate glutathione-S-transferase (GST), we used a GST:green fluorescent protein transgenic worm strain to test this hypothesis. Results from these studies indicated a statistically significant increase (p<0.001) in green pixel number following MZ exposure. Taken together, these data indicate that C. elegans treated with MZ concentrations to which humans are exposed show mitochondrial Complex I inhibition with concomitant hydrogen peroxide production. Since these mechanisms are associated with numerous human diseases, we suggest further studies to determine if MZ exposure induces similar toxic mechanisms in mammals.
有报告称，人类接触锰/锌乙撑双二硫代氨基甲酸盐（Mn/Zn-EBDC）类杀菌剂会引发多种病变，从皮炎到中枢神经系统功能障碍。尽管这类农用化学品已问世50多年，但它们对人类的毒性机制仍不清楚。由于线粒体抑制和氧化应激与多种疾病有关，我们推测，暴露于市售含Mn/Zn-EBDC杀菌剂配方（代森锰锌；MZ）中的秀丽隐杆线虫（C. elegans）也会出现这些指标变化。因此，用不同浓度的MZ对线虫进行长期（24小时）处理，并检测其线粒体功能降低和活性氧（ROS）水平升高的情况。耗氧研究表明，与对照组相比，所有处理组的复合体I均受到抑制（p<0.01）。为了验证这些发现，还完成了针对复合体II或复合体IV活性的检测。这些研究的数据分析表明，这两个复合体均未受到MZ处理的不利影响。ATP检测的其他数据表明，与对照线虫相比，所有处理组的ATP水平均有统计学意义的显著下降（p<0.001）。还完成了进一步研究，以确定秀丽隐杆线虫暴露于MZ是否也会导致ROS浓度升高。研究表明，过氧化氢水平有统计学意义的显著升高（*p<0.05），但超氧化物或羟基自由基水平未升高。由于已知过氧化氢会上调谷胱甘肽-S-转移酶（GST），我们使用了GST:绿色荧光蛋白转基因线虫品系来验证这一假设。这些研究结果表明，MZ暴露后绿色像素数量有统计学意义的显著增加（p<0.001）。综上所述，这些数据表明，用人类接触浓度的MZ处理的秀丽隐杆线虫表现出线粒体复合体I抑制并伴有过氧化氢生成。由于这些机制与多种人类疾病有关，我们建议进一步研究以确定MZ暴露是否会在哺乳动物中诱导类似的毒性机制。
