SUSCEPTIBILITY OF C57BL 6 MICE TO TUMORIGENICITY INDUCED BY DIMETHYLNITROSAMINE AND 2-AMINO-1-METHYL-6-PHENYLIMIDAZO [4,5-B]PYRIDINE IN THENEONATAL BIOASSAY/

Male C57BL/6 neonates were treated on days 8 and 15 with 2-amino-1-met hyl-6-phenylimidazo[4,5-b]pyridine (PhIP, 6.5 or 26.2 mg/kg) or dimeth ylnitrosamine (DMN, 2.6 or 10.5 mg/kg). No tumors were seen in PhIP-tr eated animals at 15 months of age. Liver and lung tumor incidences in DMN-treated animals were 67-79 and 0-7%, respectively. In comparison w ith data from other strains, our results indicate that (1) neonatally- treated C57BL/6 mice are resistant to the induction of liver and lung tumors by PhIP and lung tumors by DMN and (2) the susceptibility of th is strain to induced liver tumors correlates with the activity of hepa tic DMN N-demethylase and PhIP N-hydroxylase in the (untreated) neonat es. Published by Elsevier Science Ireland Ltd.