Status of ornithine decarboxylase activity and DNA synthesis in mancozeb-exposed mouse skin.

The effect of mancozeb, a fungicide, on mouse skin ornithine decarboxylase (ODC) activity and DNA synthesis was studied. ODC activity was induced after topical application of mancozeb and exhibited a peak level at 5 h. This ODC induction was dependent on the dose of mancozeb applied. Cycloheximide, an inhibitor of protein synthesis, inhibited the mancozeb-caused ODC induction, indicating the effect on enzyme protein synthesis. The rate of DNA synthesis was also increased by mancozeb, as indicated by increased [3H]thymidine incorporation into skin DNA. Induction of ODC activity and DNA synthesis are among the events probably involved in the tumorigenic action of mancozeb on mouse skin.