In vivo formation and persistence of DNA and protein adducts in mouse and rat skin exposed to (+/-)benzo[a]pyrene-4,5-oxide.
The objective of the present study was to compare DNA and protein adduct formation of benzo[a]pyrene-4,5-oxide (BPO) in vivo and to determine the persistence of the adducts in both mouse and rat epidermis. (+/-)BPO at a dose of 100 nmol/mouse and 200 nmol/rat was topically applied to male Swiss mice and Wistar rats. Three hours after application, there was 3-fold less binding of BPO to mouse epidermal DNA than to rat epidermal DNA; inversely, the amount of BPO bound to mouse skin protein was 3.6 times higher than in rat skin protein. One and three weeks after application of BPO, persistence of 17-20% of the initial amount of BPO-DNA adducts and 2-4% of initial amount of BPO bound to protein was detected in both mouse and rat skin epidermis. H.p.l.c. analysis of the enzymatic hydrolysates of DNA from mouse and rat epidermis 3 h after application of BPO showed five distinct products: one early-eluting, two BPO-deoxyguanosine (dGuo) (ratio 1.5:1) and two BPO-deoxyadenosine (dAdo) adducts (ratio 2:1). The ratio of the total modified dGuo to the total modified dAdo was 2:1. The amount of total BPO-dGuo and BPO-dAdo adducts was 3.5 times greater in rat than in mouse epidermis. Persistence of the major BPO-dAdo adduct was observed in mouse and rat epidermal DNA, and 1 and 3 weeks after topical application of BPO there was a 6-fold greater amount of the persisting BPO-dAdo adduct in rat skin epidermis than in mouse skin epidermis (4.1 and 0.66 pmol/mg DNA, respectively). Minor amounts of the BPO-dGuo were found to persist in rat skin epidermis DNA.
D000818:Animals; D001580:Benzopyrenes / Q000378:metabolism*; D000440:Butanols / Q000494:pharmacology; D002851:Chromatography, High Pressure Liquid; D004247:DNA / Q000378:metabolism*; D008297:Male; D051379:Mice; D009705:Nucleosides / Q000378:metabolism; D011506:Proteins / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012867:Skin / Q000378:metabolism*; D013045:Species Specificity; D013936:Thymidine / Q000378:metabolism; D014316:Tritium
D001580:Benzopyrenes; D000440:Butanols; D009705:Nucleosides; D011506:Proteins; D014316:Tritium; C006707:benzo(a)pyrene 4,5-epoxide; D004247:DNA; D013936:Thymidine