Study models for inducing tumors by 7,12-dimethylbenz (A) - Antracene in rat mammary gland

Abstract

Five study models (A, B, C, D, E) were used to investigate the effect of 7, 12-dimethylbenz(a)anthracene in inducing tumors in the mammary tissue of Spreague-Dawiey rats. Each group was subjected ad libitum to the foiiowing diets: group A - commercial ration; groups B/C - a semipurified linoleic acid-rích diet; group D - a semipurified saturated fatty acid-rich diet; group E - a semipurified fat diet composed of 50% soybean 0ff (rich in essential fatty acid), 25% olive oil (rich in oleic acid) and 25% coconut oil (rich in saturated fatty acid). The animais were fed through intragastric instiiation, one or two doses of DMBA dissolved in 1 ml of soybean oil Group A animais received a single 10 mg-DMBA-doses 60 days after birth. Group 8 animals received two-20 mg-DMBA -doses, the first dose 45 days after birth and the second 60 days after birth. Groups C, D and E animais were treated in the same way as group 8 animais. The control-groups were fed 1 mi-piacebo-soybean oiL DMBA induced tumors in the treated rats as visualized in the following results: 1) Groups A, B, C, O and E developed 52%, 76%, 88%, 60% and 67% tumors, respectively; 2) in the test groups A, B, C, D and E the first paipabie tumor was reported at 200 ± 52, 103 ± 36, 48 ± 1, 133 ± 62 and 183 ± 45 days after DMBA administration, respectively. 3) 14.8%, 40.7%, 97.5%, 50.0% and 41.7% of all tumors were classified as adenocarcinoma.The results suggest that study model "C" was the most effective one, inducing higher incidence of adenocarcinomas in DMBA-treated-rats, the symptons being evidenced in the shortest experimental time.