Effects of Cyclopho sphamide Dose and Sampling Time on Mouse Micronucleus Frequency in Bone Marrow

BACKGROUNDAIM: To evaluate the effects of different doses of cyclophosphamide(CP)and sampling time on mouse micronucleus frequency in bone marrow. MATERIAL AND METHODS: Young adult NIH mice were treated with a sigle dose of CP(40or80mg/kg)by intraperitoneal injection.The micronucleus freqyuency in bone marrow polychromatic erythrocytes(PCE)at different sampling time18,24,48h after treatment was evaluated. RESULTS: Our data showed:①The changing trends of the micronucleus frequencies in PCE in the two groups receiving40mg/kg and80mg/kg of CP were the same at different sampling times.The peak time of the micronucleus incidence was at24h after treatment.②The ratios of PCE to NCE of the two treated groups were not significantly different from the control group.This indicated that the mice bone marrow cells were not suppressed by one CP of40or80mg/kg by intraperitoneal injection.③The micronucleus frequency in PCE of40mg/kg was significantly different from that of80mg/kg,showing a dose-response relationship. CONCLUSION: CP can be used as a positive control of micronucleus test.The dose range of40～80mg/kg was fine,and the optimal sampling time is at24h after treatment.