肝微核试验方法的最新进展

Recent progress in liver micronucleus test

肝微核试验方法在预测遗传毒性的肝脏致癌物时有很高的灵敏度,并且在评价靶器官为肝脏的化合物的遗传毒性方面有很好的应用。与骨髓微核试验相比,肝微核试验可检测出不稳定的致癌物和代谢物保存时间很短的前体致癌物。肝微核试验方法有3种:第一是部分肝切除法,因操作繁琐、分裂素可能与被测物质相互作用,并未被纳入常规评价化合物肝脏遗传毒性的方法。第二是幼年大鼠法,因幼年大鼠体内肝细胞增殖速度较成年大鼠快很多,满足了检测肝微核所需的微核细胞积累。第三是重复给药法,已经过国际联合验证以重复给药的积累效应检测肝微核,而且可以与一般毒理研究相结合,减少实验动物使用。本文阐述了肝微核试验方法的发展历程和上述3种研究方法的方法学及其优劣势,以期为我国肝微核试验的开展提供参考依据。

Liver micronucleus （MN） assays are highly sensitive in predicting hepatocarcinogenicity and useful in evaluating genotoxic substances that target the liver. In comparison with bone marrow MN assay, liver MN assay can detect unstable mutagens or promutagens with short-lived metabolites. Liver MN assay includes three major methodologies as following. ① Partial hepatectomy （PH） method which is the first been developed. Because the methodology requires intensive labor and a possible interaction between the mitogen and the substance, it has not been used as a routine method to evaluate chemical genicity in the liver. ② Juvenile/young rat （JR） method, the liver in juvenile rat has higher cell proliferation than in adult rat liver, so livers in young rats would have sufficient numbers of replicating cells to provide sensitivity for detecting MN. ③ Repeated-dose （RD） method which has already been tested by international collaborative study using accumulative effect of multiple dosing. It can compensate for the lower mitotic activity and can be integrated into a general toxicological study, thereby reducing the numbers of animals required. Here the development of liver micronucleus assays were introduced, and the strength and weakness of the three methodologies were also demonstrated. These may provide some key references for the application of liver micronucleus assay.