Immunohistochemical detection of 1,N-6-ethenodeoxyadenosine, a promutagenic DNA adduct, in liver of rats exposed to vinyl chloride or an iron overload

Etheno adducts in DNA bases are formed from exogenous agents such as vinyl chloride and urethane, but also via endogenous lipid peroxidation products like trans-4-hydroxy-2-nonenal. An immunohistochemical method was developed to localize the promutagenic 1,N-6-ethenodeoxy-adenosine DNA adduct in liv er of rats exposed to vinyl chloride or an iron overload with or without ca rbon tetrachloride. Six monoclonal antibodies, previously produced through collaborative efforts, were screened for their optimal adduct recognition a nd low background formation, The antibody generated by done EM-A-4 was foun d to be most suitable, Semi-quantitative image analysis of relative pixel i ntensity showed similar to 1.5 times higher adduct levels (P < 0.05) in the livers of rats treated with vinyl chloride or an iron overload when compar ed with untreated controls. Significantly elevated adduct levels persisted in vinyl chloride-treated rat liver 14 days after cessation of exposure, su ggesting that this adduct is not rapidly eliminated from rat liver DNA, Usi ng the new immunohistochemical method it is possible to visualize this prom utagenic etheno-DNA adduct that may play a role in oxidative stress and lip id peroxidation-induced DNA damage in carcinogenesis.