Influences of Genetic Factors on the Teratogenicity of Environmental Pollutants : Teratogenic Susceptibility to Benzo[a]pyrene and Ah Locus in Mice

Abstract

C57BL/6 female mice were mated with C57BL/6, DBA/2 or BDF_1 male mice (B-Groups), and DBA/2 female mice were mated with DBA/2, C57BL/6 or BDF_1 males (D-Groups). C57BL/6 mice are Ah responsive (aromatic hydro-carbon responsive) and DBA/2 mice are Ah nonresponsive. On day 8 of pregnancy, mice of each group were injected ip with benzo [a] pyrene (BP) in corn oil at a dose of 150 or 300 mg/kg. Untreated and vehicle treated pregnant mice served as controls. Pregnant mice were killed on day 18 and the fetuses were examined for mortality, growth, external and skeletal abnormalities. Fetal mortality increased with the dose of BP in all the experimental groups except the mating group of DBA/2 × DBA/2. The decrease of fetal body weight was dose dependent in all groups, and was more prominent in D-Groups than in B-Groups. The incidence of cervical ribs increased with the dose of BP in D-Groups but not in B-Groups. These results suggest that fetuses with Ah responsive genotype were more susceptible to BP in terms of fetal mortality and the fetuses from the mothers with Ah nonresponsive genotype were more susceptible in terms of the decrease in fetal body weight and the increase in the incidence of cervical ribs.