Comparative toxicologic study of 2,3,7,8-tetrachlorodibenzo-p-dioxin in Ah responsive and nonresponsive strains of mice

In order to evaluate in more detail the segregation of the toxicity of TCDD with the Ah genotype, we used three inbred strains of mice chosen from each of the Ah responsive and nonresponsive ones. Significant changes in the weight of the liver and thymus and severer hepatic lesions were observed only in the three Ah responsive strains after TCDD administration. Other toxic indicators, however, such as a gain or loss in the weight of the body, the induction of AHH activity, the number of lymphocytes, and the mitotic index, were not necessarily changed by the Ah genotype. The genetic regulation of toxicity caused by TCDD was considered not to be simple, and the results of this study support the idea that some genes other than the Ah locus are involved in the development of TCDD-induced toxicity.