Induction of unscheduled DNA synthesis in rat and hamster hepatocytes by cooked food mutagens.
The genotoxicity of the cooked-food mutagens 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx), 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2) was studied by monitoring the induction of DNA repair (unscheduled DNA synthesis; UDS) in primary cultures of rodent hepatocytes. The hepatocytes were derived from male Sprague-Dawley rats or Syrian hamsters by collagenase perfusion and the cells were cultured for 4 hr before being exposed to various concentrations of the mutagens. DNA repair was determined by measuring incorporation of [3H]thymidine into extracted DNA over 17 hr using beta-scintillation counting. Dose-related increases in UDS were clearly seen in hamster hepatocytes treated with MeIQ, IQ and the positive control 2-acetylaminofluorene (AAF), and a weak response was induced by MeIQx and Trp-P-1. In the rat hepatocytes only MeIQ and AAF gave clear positive responses. Furthermore it was noted that all the mutagens displayed a more pronounced UDS response in hamster hepatocytes than in rat cells. Studies of the activation of MeIQ by hepatocytes to a bacterial mutagen suggest that this difference is probably a consequence of the greater capacity of hamster cells to activate the mutagens to genotoxic metabolites.
D000818:Animals; D001711:Biotransformation; D002243:Carbolines / Q000633:toxicity*; D006224:Cricetinae; D004247:DNA / Q000096:biosynthesis; D004260:DNA Repair / Q000187:drug effects*; D008099:Liver / Q000378:metabolism*; D008297:Male; D008647:Mesocricetus; D009153:Mutagens / Q000378:metabolism; D011804:Quinolines / Q000633:toxicity*; D011810:Quinoxalines / Q000633:toxicity*; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity
D002243:Carbolines; D009153:Mutagens; D011804:Quinolines; D011810:Quinoxalines; C029216:2-amino-3-methylimidazo(4,5-f)quinoline; C036990:2-amino-3,8-dimethylimidazo(4,5-f)quinoxaline; C019133:3-amino-1-methyl-5H-pyrido(4,3-b)indole; D004247:DNA; C036989:2-amino-3,4-dimethylimidazo(4,5-f)quinoline; C019132:3-amino-1,4-dimethyl-5H-pyrido(4,3-b)indole