Heinloth Alexandra N, Irwin Richard D, Boorman Gary A, Nettesheim Paul, Fannin Rickie D, Sieber Stella O, Snell Michael L, Tucker Charles J, Li Leping, Travlos Gregory S, Vansant Gordon, Blackshear Pamela E, Tennant Raymond W, Cunningham Michael L, Paules Richard S
National Center for Toxicogenomics, National Institute of Environmental Health Sciences, P.O. Box 12233, Research Triangle Park, North Carolina 27709, USA.
Toxicol Sci. 2004 Jul;80(1):193-202. doi: 10.1093/toxsci/kfh145. Epub 2004 Apr 14.
This study tested the hypothesis that gene expression profiling can reveal indicators of subtle injury to the liver induced by a low dose of a substance that does not cause overt toxicity as defined by conventional criteria of toxicology (e.g., abnormal clinical chemistry and histopathology). For the purpose of this study we defined this low dose as subtoxic, i.e., a dose that elicits effects which are below the detection of conventional toxicological parameters. Acetaminophen (APAP) was selected as a model hepatotoxicant because (1) considerable information exists concerning the mechanism of APAP hepatotoxicity that can occur following high doses, (2) intoxication with APAP is the leading cause of emergency room visits involving acute liver failure within the United States, and (3) conventional clinical markers have poor predictive value. Rats treated with a single dose of 0, 50, 150, or 1500 mg/kg APAP were examined at 6, 24, or 48 h after exposure for conventional toxicological parameters and for gene expression alterations. Patterns of gene expression were found which indicated cellular energy loss as a consequence of APAP toxicity. Elements of these patterns were apparent even after exposure to subtoxic doses. With increasing dose, the magnitude of changes increased and additional members of the same biological pathways were differentially expressed. The energy loss suggested by gene expression changes was confirmed at the 1500 mg/kg dose exposure by measuring ATP levels. Only by ultrastructural examination could any indication of toxicity be identified after exposure to a subtoxic dose of APAP and that was occasional mitochondrial damage. In conclusion, this study provides evidence that supports the hypothesis that gene expression profiling may be a sensitive means of identifying indicators of potential adverse effects in the absence of the occurrence of overt toxicity.
基因表达谱分析能够揭示低剂量物质对肝脏造成的细微损伤的指标，该低剂量物质按照传统毒理学标准（如异常临床化学指标和组织病理学）并未造成明显毒性。在本研究中，我们将这种低剂量定义为亚毒性剂量，即引发的效应低于传统毒理学参数检测水平的剂量。选择对乙酰氨基酚（APAP）作为肝毒性模型药物，原因如下：（1）关于高剂量APAP导致肝毒性的机制已有大量信息；（2）在美国，APAP中毒是急诊室急性肝衰竭病例的主要病因；（3）传统临床标志物的预测价值较差。对接受0、50、150或1500 mg/kg APAP单次剂量处理的大鼠，在暴露后6、24或48小时检测其传统毒理学参数及基因表达变化。发现了基因表达模式，这些模式表明APAP毒性导致细胞能量损失。即使在暴露于亚毒性剂量后，这些模式的要素也很明显。随着剂量增加，变化幅度增大，相同生物学途径的其他成员也出现差异表达。通过测量ATP水平，证实了在1500 mg/kg剂量暴露时基因表达变化所提示的能量损失。在暴露于亚毒性剂量的APAP后，只有通过超微结构检查才能发现任何毒性迹象，且仅偶尔出现线粒体损伤。总之，本研究提供的证据支持了这样一个假设：在未出现明显毒性的情况下，基因表达谱分析可能是识别潜在不良反应指标的一种敏感方法。
