Assessment of basal and induced DNA damage on lymphocytes from three mouse lines by means of the alkaline comet assay

The formation of single-strand breaks and alkali-labile sites on DNA has been extensively used for genotoxicity testing, given its involvement in degenerative disorders, cancer and oxidative stress. An alkaline variation of the single-cell electrophoresis (comet) assay used for the detection of DNA damage was developed during the eighties, providing data on this phenomenon at the level of individual cells for the first time. The present work employs the alkaline comet assay to compare three mouse lines regarding the basal and cyclophosphamide-induced frequency of single-strand breaks and the appearance of alkali-labile sites in DNA from peripheral blood lymphocytes. A total of 10 mice/sex/ group of the Balb/c, OF-1 and NMRI lines were treated for 14 days, distributed into an untreated negative control group, two groups receiving excipients and a positive control group receiving intraperitoneal cyclophosphamide at 50 mg/kg. After 14 days, single cells from peripheral blood leukocytes were analyzed by alkaline electrophoresis to estimate DNA damage. It was concluded that the best choice for this type of studies is represented by the Balb/c line, due to its low basal frequency for the analyzed variables. This result indicates that Balb/c may be the best biomodel for preclinical testing of drugs, vaccines and other products.