Mouse spot tests with dimethylbenz[a]anthracene with and without phenobarbital pretreatment

Mouse spot tests using dimethylbenz[a]anthracene (DMBA) were carried out on PW strain male mice and female C57BL/6 mice. DMBA induced somatic gene mutations in developing mouse embryonic cells. Pretreatment of pregnant females with phenobarbital (PB) reduced the incidence of somatic mutation by DMBA. The testes of males treated with DMBA in utero, whether treated with PB or not, showed severe retardation of development. The amount of cytochrome p-450 in the liver of C57BL/6 females increased about 2-fold by the pretreatment schedule, carried out on days 10-12 of pregnancy.