title: Use of the in vivo skin comet assay to evaluate the DNA-damaging potential of chemicals applied to the skin.
abstract: The aim of the present study was to evaluate both sensitivity and specificity of an in vivo skin comet assay using chemically treated, hairless mouse dorsal skin as a model. N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 0.0125-0.2%), 4-nitroquinoline-1-oxide (4NQO, 0.01-0.25%), mitomycin C (MMC, 0.0125-0.05%), benzo[a]pyrene (B[a]P, 0.25-2%), and 7,12-dimethylbenz[a]anthracene (DMBA, 0.25-1%) were each applied once to the dorsal skin of hairless male mice; after 3h, epidermal skin cells were isolated, and the alkaline comet assay was performed. The assay was performed after 24h for only the B[a]P and DMBA. Furthermore, B[a]P and DMBA were evaluated by alkaline comet assay using liver cells after both 3 and 24h. The mean percent of DNA (%DNA) in tail in the 0.05-0.2% MNNG and 0.1-0.25% 4NQO treatment groups was markedly higher than in the control group at 3h post-application. Although the mean %DNA values in the tail in the B[a]P and DMBA groups were the same as the controls at 3h post-application, the 2% B[a]P and 1% DMBA groups showed significantly higher values versus controls 24h after application. No significant increases in the mean %DNA in the tail were observed in the MMC group. No clear increases in %DNA in the tail were observed in the B[a]P and DMBA groups at 3 or 24h after application in the liver. These results suggest that the in vivo skin comet assay is able to accurately identify DNA-damaging potential with a skin-specific response and is a useful method to detect the DNA-damaging potential of genotoxic chemicals on the skin.
authors.affiliation: Food and Drug Safety Center, Hadano, Kanagawa, Japan. tomoyasu_toyo@yahoo.co.jp
authors.forename: Tomoyasu
authors.initials: T
authors.lastname: Toyoizumi
authors.forename: Ryo
authors.initials: R
authors.lastname: Ohta
authors.forename: Yuzuki
authors.initials: Y
authors.lastname: Nakagawa
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Tazura
authors.forename: Makiko
authors.initials: M
authors.lastname: Kuwagata
authors.forename: Satoshi
authors.initials: S
authors.lastname: Noguchi
authors.forename: Kohji
authors.initials: K
authors.lastname: Yamakage
mesh_terms: D000818:Animals; D020552:Comet Assay / Q000379:methods*; D004249:DNA Damage; D008297:Male; D051379:Mice; D008812:Mice, Hairless; D009153:Mutagens / Q000633:toxicity*; D012680:Sensitivity and Specificity; D012867:Skin / Q000187:drug effects*
chemical_list: D009153:Mutagens