Evaluation of the rodent micronucleus assay by a 28‐day treatment protocol: Summary of the 13th Collaborative Study by the Collaborative Study Group for the Micronucleus Test (CSGMT)/Environmental Mutagen Society of Japan (JEMS)–Mammalian Mutagenicity Study Group (MMS)

• DOI: 10.1002/em.1017
• Publication Date: 2002-08-25T21:43:33Z
• Authors: Shuichi Hamada; Sizuyo Sutou; Takeshi Morita; Akihiro Wakata; Shougo Asanami; Satoko Hosoya; Shigenari Ozawa; Koji Kondo; Madoka Nakajima; Hiroyasu Shimada; Koichi Osawa; Yasushi Kondo; Norihide Asano; Sei‐ichi Sato; Hironobu Tamura; Nobuhiro Yajima; Richard Marshall; Catherine Moore; David H. Blakey; Leonard M. Schech...; James L. Weaver; Dorothea K. Torous; Ray Proudlock; Seiichi Ito; Chiaki Namiki; Makoto Hayashi
• Keywords: Dose; Clastogen

To examine whether micronucleus tests can be incorporated into general toxicology assays, we performed applying the treatment protocols typically used in such assays. In this 13th Collaborative Study of CSGMT, both rats and mice were tested, although majority studies. Fifteen mutagens tested rats, mainly by oral (p.o.) administration. Micronucleus induction was evaluated 2, 3, 4 days, 1, 28 days after beginning peripheral blood, at bone marrow. Of 15 chemicals that induced micronuclei short-term two (1,2-dimethylhydrazine.2HCl mitomycin C) negative all our experiments, possibly because insufficient dose levels. The remaining 13 positive within estimated range a assay, suggesting possibility integrating assay Three patterns observed during period repeated treatment: (1) gradual increases frequency with sequential doses, (2) peak 3-5 followed decreases (3) rapid increase plateau. We factors might have been involved those patterns, as spleen function, target organ exposure, extramedullary hematopoiesis, hypothermia, hypoxia. Another factor considered dosage. Because dosages employed toxicity are usually lower than discrepancy greatest potential problem for Our results indicate integration 28-day toxicological is feasible. serve purpose, blood samples collected marrow autopsy should examined. Furthermore, it recognized may suitable performing independent propose provide biologically important relevant information regarding chemical under conditions conduct