Effect and mechanism of benzo(a)pyrene on DNA damage of thymocytes in mice

Objective To study the effect of benzo(a)pyrene on DNA damage of thymocytes and its mechanism in mice.Methods Single cell gel electrophoresis technique was used to detect the DNA damage of thymocytes in mice exposed to benzo(a)pyrene at different concentrations with or without metabolism activating system(S9) and the DNA damage after adding N-acetyl-L-cysteine(NAC) to the reaction system.Nitric oxide(NO) concentrations of thymocytes in mice exposed to benzo(a)pyrene were determined by colorimetric method.Results The migrating distances of DNA of thymocytes in mice exposed to 10~(-4),10~(-5),10~(-6) mol/L benzo(a)pyrene(+S9) respectively were(42.14±5.23),(25.36±2.96),(18.78±1.72) μm.The difference was significant among the treated groups and the solvent control group(11.25±0.92) μm.The migrating distances of DNA after adding NAC to the positive group declined singnificantly.No concentrations didn't increase significantly.Conclusion Benzo(a)pyrene causes the DNA damage of thymocytes in mice,which might relate with its metabolite——reactive oxygen species(ROS),but not NO.