REDUCTION IN THE TRANSPLACENTAL CARCINOGENIC EFFECT OF METHYLCHOLANTHRENE IN MICE BY PRIOR TREATMENT WITH BETA-NAPHTHOFLAVONE

  • 1 January 1980
    • journal article
    • research article
    • Vol. 30  (3) , 431-446
Abstract
Conversion of 14C-benzol[a]pyrene (BP) to alkali-soluble and water-phase products, as a measure of aryl hydrocarbon metabolism, was assayed on day 18 of gestation in the livers of pregnant C57BL/6 females and their (C57BL/6 .times. BALB/c)F1 fetuses. BP metabolism was inducible in maternal and fetal livers by .beta.-naphthoflavone (.beta.-NF), injected i.p. on day 16 of gestation at doses of 25-130 mg/kg. At 25 and 75 mg/kg .beta.-NF, fetal liver metabolism of BP was induced 1.5- and 4.5-fold, respectively. Maternal liver was not affected at 25 mg/kg and induced 2.6-fold at 75 mg/kg. In a complementary assay, pregnant mothers were injected i.p. with .beta.-NF (25 or 75 mg/kg) on day 15 of gestation and 3-methylcholanthrene (MC) (30 or 150 mg/kg) on day 17. The progeny were examined for lung tumors at 28 wk. The average number of lung tumors per mouse caused by 150 mg/kg Mc was significantly reduced by prior treatment with .beta.-NF, to an extent depending on the dose of the inducer. With the 75 mg/kg dose of .beta.-NF, the incidence of lung tumors was reduced by half. Induction of carcinogen detoxification in maternal, fetal and/or placental tissue is a possible mechanism by which .beta.-NF protected against transplacental MC tumorigenesis.