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Micronucleated reticulocyte induction by ethylating agents in mice.
A O Asita1, M Hayashi, Y Kodama
1Division of Genetics and Mutagenesis, National Institute of Hygienic Sciences, Tokyo, Japan.
Mutation Research
|February 1, 1992
Summary
This study introduces a new micronucleus assay using mouse peripheral blood and acridine orange-coated slides to assess clastogenic potency. N-ethyl-N-nitrosourea (ENU) showed the highest potency, while epichlorohydrin (ECH) and ethylene dibromide (EDB) did not induce micronucleated reticulocytes.
Area of Science:
- Toxicology
- Genetics
- Biotechnology
Background:
- Clastogenic agents can cause DNA damage, leading to mutations and potential health risks.
- Accurate and sensitive methods are crucial for evaluating the genotoxicity of chemical compounds.
- Existing in vivo assays for clastogenicity have varying levels of sensitivity and complexity.
Purpose of the Study:
- To evaluate the clastogenic potency of six model ethylating agents.
- To validate a new micronucleus assay technique using mouse peripheral blood cells and acridine orange-coated slides.
- To compare the sensitivity and effectiveness of this new assay with existing in vivo methods.
Main Methods:
- Six ethylating agents (N-ethyl-N'-nitro-N-nitrosoguanidine, N-ethyl-N-nitrosourea, diethyl sulfate, ethyl methanesulfonate, epichlorohydrin, and ethylene dibromide) were administered to mice via intraperitoneal injection.
- Blood samples were collected at 24-hour intervals up to 72 hours post-injection.
- Micronucleated reticulocytes (MNRETs) were analyzed in acridine orange-stained peripheral blood smears, examining 1000 reticulocytes per slide.
- Dose-response relationships were established to determine the clastogenic potency of each agent.
Main Results:
- N-ethyl-N-nitrosourea (ENU) induced micronucleated reticulocytes (MNRETs) significantly at all tested doses.
- N-ethyl-N'-nitro-N-nitrosoguanidine (ENNG) and ethyl methanesulfonate (EMS) showed significant MNRET induction at two dose levels each.
- Diethyl sulfate (DES) induced MNRETs only at the highest dose, while epichlorohydrin (ECH) and ethylene dibromide (EDB) failed to induce MNRETs.
- The determined order of clastogenic potency was ENU > ENNG > EMS > DES.
Conclusions:
- The new micronucleus assay technique is simple, flexible, and relatively sensitive for evaluating clastogenic potency.
- The assay effectively identified potent clastogens like ENU and weaker ones like DES.
- This method is valuable for testing weak mutagens and chemicals with unknown mechanisms of action, offering results comparable to other in vivo methods.