title: Effects of fetal exposure to diethylstilbestrol on mammary tumorigenesis in rats.
abstract: The aim of this study was to investigate the effect of fetal exposure to diethylstilbestrol (DES) on the induction of mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in female rats. Pregnant rats were fed only normal diet, diet mixed with 0.1 ppm DES throughout pregnancy period or diet mixed with 0.1, 1 or 10 ppm DES from day 13 of pregnancy till the end of pregnancy. Delivered pups were given 10 mg DMBA by gastric intubation at 50 days after birth and observed till 336 days after birth. Some rats exposed to DES throughout pregnancy and those from day 13 till the end of pregnancy showed endocrine disrupting effects such as absence of CL and active lactation in mammary glands at necropsy, while no abnormal estrus cycle such as persistent estrus was seen during the observation period until 88 days after birth. Fetal exposure to 0.1 ppm DES throughout pregnancy period, 0.1 and 1 ppm DES from day 13 of pregnancy increased the incidence and number of mammary carcinomas (MCs) at the earlier period while exposure to 0.1 ppm DES throughout pregnancy period enhanced the incidence and number of benign proliferative lesions (PLs) at the later period. MCs appeared earlier than benign PLs. These results suggest that exposure to DES throughout pregnancy and from day 13 of pregnancy could induce endocrine disrupting conditions and enhance the induction of MCs and that exposure to DES throughout pregnancy enhance PLs.
authors.affiliation: Department of Veterinary Experimental Animal Science, Kagoshima University, Korimoto,Kagoshima 890-0065, Japan
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kawaguchi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Miyoshi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Miyamoto
authors.forename: Masakazu
authors.initials: M
authors.lastname: Souda
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Umekita
authors.forename: Nobuhiro
authors.initials: N
authors.lastname: Yasuda
authors.forename: Hiroki
authors.initials: H
authors.lastname: Yoshida
mesh_terms: D000375:Aging; D000818:Animals; D004054:Diethylstilbestrol / Q000009:adverse effects*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D015674:Mammary Neoplasms, Animal / Q000139:chemically induced*; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced / Q000473:pathology; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats
chemical_list: D004054:Diethylstilbestrol