A comparison of micronucleus induction in 3 mouse strains with representative clastogens.

The frequency of micronucleated polychromatic erythrocytes (MNPCEs) was compared in BALB/c, C57BL/6 and DBA/2 mice after the intraperitoneal injection (i.p.) of methyl methanesulfonate (MMS), potassium chromate (K2CrO4), colchicine (COL), cycloheximide (CYH), 4-nitroquinoline-1-oxide (4-NQO) and 5-fluorouracil (5-FU). In BALB/c mice, the frequency of MNPCEs was significantly increased by all the chemicals tested, as compared to the vehicle control. In both C57BL/6 and DBA/2 mice, MMS, K2CrO4, COL and 4-NQO significantly increased MNPCEs, but CYH and 5-FU only slightly increased the MNPCEs in C57BL/6 and had no effect on DBA/2 mice. These results suggest that BALB/c mice are more sensitive to the induction of MNPCEs with a wider spectrum of chemicals than C57BL/6 or DBA/2 mice.