摘要：The effect of pretreatment with zinc (Zn) compounds on the mutagenicity of benzo[ a ]pyrene (B[ a ]P) was investigated using metallothionein (MT)-I/II null mice. MT-I/II null mice and wild-type mice were subcutaneously administered ZnSO4 once a day for 2 days and gavaged B[ a ]P at 24 hr after the last injection of ZnSO4. B[ a ]P-induced micronucleus frequencies were reduced by Zn pretreatment in the wild-type mice but not in the MT-I/II null mice. Zn administration significantly increased the concentration of MT in the liver and bone marrow cells of wild-type mice, but the statuses of other cellular antioxidants, such as glutathione, catalase and superoxide dismutase, were unchanged. In addition, the activity of a major B[ a ]P metabolic activation enzyme, cytochrome P450 1A, was unchanged by Zn treatment in both MT-I/II null mice and wild-type mice. These results suggest that Zn pretreatment protects against the mutagenicity of B[ a ]P through the induction of MT synthesis. The amount of MT produced in animals may determine their sensitivity to B[ a ]P exposure.
