Induction of ornithine decarboxylase by aromatic amines in rat liver.

The induction of ornithine decarboxylase (ODC) in rat liver by the carcinogen 2-acetylaminofluorene (2AAF), the strong liver tumor initiator trans-4-acetylaminostilbene (AAS), the non-carcinogen 4-acetylaminofluorene (4AAF) and, as a control, 3-methylcholanthrene (MC) has been examined. MC and all aromatic amines increased the ODC activity of rat liver from 3.6-fold (MC) to maximal 5.7-fold (AAS). The time course of the maximal induction differs from 2.5 h (2AAF) to 10 h (MC). The cytosolic concentrations of the unchanged compounds parallel the ODC activity. These data indicate that ODC induction in rat liver shows no correlation with tumor promoting properties of the model compounds. It is concluded that the unchanged compound is responsible for the ODC induction.