title: Lack of enhancing effects of sodium nitrite on 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mammary carcinogenesis in female Sprague-Dawley rats.
abstract: A number of heterocyclic amines (HCAs) have been shown to exert enhanced carcinogenic and mutagenic potential when given simultaneously with sodium nitrite (NaNO(2)). In the present experiment, effects of combined treatment with NaNO(2) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), one of the most prevalent carcinogenic HCAs in the human environment, were assessed with regard to mammary tumor induction in female Sprague-Dawley (SD) rats. Animals at 6 weeks of age were given intragastric doses of 100mg/kg body weight of PhIP twice a week for 4 weeks, during which period 0 or 0.2% NaNO(2) was administered in the drinking water. Control rats received 0.2% NaNO(2) alone for the 4 weeks or non-supplemented water during the entire 48 week experimental period, without carcinogen treatment. The first tumor in the PhIP+NaNO(2) group appeared significantly later than with PhIP alone, and during the experimental period, the incidence, multiplicity and volume of mammary tumors in this group tended towards decreased, although values did not significantly differ at the terminal sacrifice. These results indicate that NaNO(2) does not enhance PhIP-induced rat mammary carcinogenesis, rather possessing some potential for inhibition.
authors.affiliation: Division of Pathology, National Institute of Health Sciences, 1-18-1 Kamiyoga, Tokyo 158-8501, Japan.
authors.forename: Yasuki
authors.initials: Y
authors.lastname: Kitamura
authors.forename: Megumi
authors.initials: M
authors.lastname: Yamagishi
authors.forename: Kazushi
authors.initials: K
authors.lastname: Okazaki
authors.forename: Fumio
authors.initials: F
authors.lastname: Furukawa
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Imazawa
authors.forename: Akiyoshi
authors.initials: A
authors.lastname: Nishikawa
authors.forename: Masao
authors.initials: M
authors.lastname: Hirose
mesh_terms: D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002273:Carcinogens / Q000633:toxicity*; D016923:Cell Death / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D004357:Drug Synergism; D005260:Female; D007093:Imidazoles / Q000633:toxicity*; D015994:Incidence; D007202:Indicators and Reagents / Q000494:pharmacology*; D015674:Mammary Neoplasms, Animal / Q000139:chemically induced*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012977:Sodium Nitrite / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
chemical_list: D002273:Carcinogens; D007093:Imidazoles; D007202:Indicators and Reagents; C049584:2-amino-1-methyl-6-phenylimidazo(4,5-b)pyridine; D012977:Sodium Nitrite