Synergistic effect of chronic prolactin suppression and retinoid treatment in the prophylaxis of N-methyl-N-nitrosourea-induced mammary tumorigenesis in female Sprague-Dawley rats.

摘要: Two hundred forty Sprague-Dawley rats were treated i.v. with 2.5 or 1.25 mg of N-methyl-N-nitrosourea (MNU) per 100 g body weight at 50 and 57 days age. At 60 age, given either dose divided into 4 groups (30 rats/group) as follows: Group 1, controls; 2, 0.4 2-bromo-alpha-ergocryptine (CB-154) injected s.c. once daily; 3, retinyl acetate (328 mg/kg diet) fed 4, CB-154 treatments combined. Rats that received the 2.5-mg MNU for 129 days; those 1.25-mg 175 days. The high maintained without any treatment an additional 13 weeks, after which they sacrificed. low carcinogen sacrificed immediately treatment. All palpated weekly palpable mammary tumors. number tumors total cessation were, respectively, follows. (2.5 mg): 22 30 (73%), 82: 11 (37%), 17; 19: 2 (7%), 2. (1.25 8 (27%), 14; (13%), 5; 3 (10%), 4; 0 30, (0%), 0. Thus, chronic feeding markedly reduced percentage rates bearing combined superior to alone, inasmuch tumorigenesis was nearly completely blocked in totally MNU. Retinyl CB-154-induced prolactin suppression appear be equally effective prophylaxis MNU-induced rats; modality, however, appears far than alone.