Inhibitory Effects of Diallyl Bisulfide or Aspirin on 2‐Amino‐l‐methyl‐6‐phenylimidazo[4,5‐b]pyridine‐induced Mammary Carcinogenesis in Rats

Abstract

Modifying effects of diallyl disulfide (DAD), aspirin or DL‐α‐difluoromethylornithine (DFMO) on 2‐amino‐l‐methyl‐6‐phenyIimidazo[4,5‐b]pyridine (PhlP)‐induced mammary carcinogenesis in SD rats were investigated. A total of 166 female rats, 6 weeks old, were divided into 8 groups. They were fed a high fat diet throughout the experiment. Starting at 7 weeks of age, groups 1–4 were given PhIP (85 rag/kg body weight in corn oil) by gavage 8 times in 10 days, and groups 58 were given corn oil alone. For the beginning 4 weeks, groups 2 and 5 were given DAD at 200 ppm in diet. Similarly groups 3 and 6, and groups 4 and 7 were given aspirin (400 ppm) and DFMO (400 ppm), respectively. Mammary carcinomas were only recognized in groups 1–4 at the termination (25 weeks after the start of experiment). Multiplicity (mean number/rat) of neoplasms in group 2 (PhIP+DAD, 0.90/rat) and group 3 (PhIP+aspirin, 1.37/rat) was significantly smaller than that in group 1 (PhIP alone, 2.457 rat) (P < 0.005 and P < 0.05, respectively). These results indicate that dietary intake of DAD or aspirin during the time corresponding to initiation phase has chemopreventive potential on PhlP‐induced mammary carcinogenesis in rats.