title: Influence of strain and sex on the local development of mammary tumors induced by direct application of DMBA powder to rat mammary glands.
abstract: In order to determine the influence of strain and sex on local carcinogenesis in rat mammary tissue, 1 mg of 7,12-dimethylbenz(a)anthracene (DMBA) was dusted directly onto the exposed mammary gland of 30-day-old Long-Evans (L-E) rats and Sprague-Dawley (S-D) rats. The experiment was terminated 28 weeks after application of the carcinogen. Tumors measuring between 1 and 2 cm in diameter were harvested from female L-E rats with high frequency (85%) and long latency (mean: 23.7 weeks after DMBA dusting), and from female S-D rats with extremely high frequency (98%) and short latency (16.7 weeks). Male rats of both strains were almost identically much less susceptible to DMBA (L-E; 55%, 25.0 weeks, S-D; 53%, 23.9 weeks). Ovariectomized S-D (47%, 24.9 weeks) and orchiectomized S-D (30%, 24.8 weeks) rats, which were gonadectomized at 30 days of age, respectively, were also much less susceptible. A variety of histologies, mostly malignant epithelial, mesenchymal or mixed tumors, were noted in each group. The carcinomatous response in the mammary tissue was much higher in female S-D (96%) than in female L-E (50%) rats, and very low in male and gonadectomized rats (10-20%). In contrast, the sarcomatous response in the mammary tissue was moderate in female and male L-E and male S-D (43-50%) rats, and low in the other groups (15-29%).
authors.affiliation: Department of Pathology, Kansai Medical University, Moriguchi, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Tsubura
authors.forename: Y
authors.initials: Y
authors.lastname: Izuno
authors.forename: T
authors.initials: T
authors.lastname: Shoji
authors.forename: N
authors.initials: N
authors.lastname: Kusunose
authors.forename: S
authors.initials: S
authors.lastname: Morii
mesh_terms: D015127:9,10-Dimethyl-1,2-benzanthracene / Q000008:administration & dosage; D000230:Adenocarcinoma / Q000139:chemically induced* / Q000209:etiology / Q000473:pathology; D000287:Administration, Topical; D000818:Animals; D004195:Disease Models, Animal; D005260:Female; D008297:Male; D008321:Mammary Glands, Animal / Q000187:drug effects; D008325:Mammary Neoplasms, Experimental / Q000139:chemically induced* / Q000209:etiology / Q000473:pathology; D009919:Orchiectomy; D010052:Ovariectomy; D051381:Rats; D011919:Rats, Inbred Strains / Q000235:genetics*; D012727:Sex Characteristics
chemical_list: D015127:9,10-Dimethyl-1,2-benzanthracene