Evaluation of the general suitability of the rat for the micronucleus assay: the effect of cyclophosphamide in 14 strains

To evaluate the general suitability of the rat for the micronucleus assay, we conducted the assay in males of 14 different strains, 13 inbred (ACI, BN , BUF, COP, DRH, F344, IS, LEW, RCS, SHR, WAG, WKYO, WTC) and 1 outbred (SD ), using cyclophosphamide as the test chemical. Cyclophosphamide at 0 (vehi cle), 5, 10, or 20 mg/kg, per day was administered orally twice, 24 h apart , to five rats per dosage group. Bone marrow and peripheral blood were coll ected 24 h after the second treatment. All 14 strains showed a positive response to cyclophosphamide, with slight differences in sensitivity. We concluded that the rat is suitable for the m icronucleus assay regardless of strain. (C) 2001 Elsevier Science B.V. All rights reserved.