Effects of fetal exposure to 4-n-octylphenol on mammary tumorigenesis in rats.
BACKGROUND
The aim of this study was to investigate the effect of fetal exposure to 4-n-octylphenol (OP) on the induction of mammary tumors induced by 7,12-dimethylbenz[a]anthracene (DMBA) in rats.


METHODS
All rats which showed vaginal plugs or sperm by vaginal smear test after mating were fed a normal diet only, or a diet mixed with 10, 100, 1000 ppm OP throughout the pregnancy period and from day 13 of pregnancy to the end of the pregnancy. No abnormal pregnancy was seen in any of the rats. Pups were given 10 mg DMBA by gastric intubation 50 days after birth.


RESULTS
Uterine weight decrease was observed in pups with fetal exposure to 1000 ppm OP throughout the pregnancy period. No endocrine disrupting conditions, such as persistent estrus, anovulatory ovaries or abnormal lactation in the mammary glands were seen in pups with fetal exposure to OP. However, fetal exposure to 100 and 1000 ppm OP throughout pregnancy period enhanced the early incidence and number of mammary carcinomas (MCs) while it did not enhance the incidence and number of benign proliferative lesions (PLs) which consisted of solid masses (fibroadenoma and lobular hyperplasia) and gross cysts.


CONCLUSIONS
These results suggest that fetal exposure to the very weak estrogenicity of OP could enhance the induction of MCs but not affect the induction of PLs.
Kawaguchi
Hiroaki
H
DVM, Department of Veterinary Pathology, Faculty of Agriculture, Kagoshima University, 1-21-24 Korimoto, Kagoshima 890-0065, Japan.
Miyoshi
Noriaki
N
Miyamoto
Yoko
Y
Souda
Masakazu
M
Umekita
Yoshihisa
Y
Yasuda
Nobuhiro
N
Yoshida
Hiroki
H
D015127:9,10-Dimethyl-1,2-benzanthracene / Q000633:toxicity; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D001943:Breast Neoplasms / Q000453:epidemiology; D002273:Carcinogens / Q000633:toxicity; D002455:Cell Division / Q000187:drug effects; D004054:Diethylstilbestrol / Q000633:toxicity; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000633:toxicity; D004971:Estrus / Q000187:drug effects; D005260:Female; D005333:Fetus / Q000187:drug effects; D006801:Humans; D015674:Mammary Neoplasms, Animal / Q000139:chemically induced* / Q000473:pathology; D009929:Organ Size / Q000187:drug effects; D010636:Phenols / Q000633:toxicity*; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley; D043343:Testosterone Propionate / Q000633:toxicity; D015430:Weight Gain / Q000187:drug effects
D002273:Carcinogens; D010636:Phenols; D004958:Estradiol; D015127:9,10-Dimethyl-1,2-benzanthracene; D004054:Diethylstilbestrol; C080417:4-octylphenol; D043343:Testosterone Propionate