Changes in ornithine decarboxylase activity in rat intestines during aging.

The ornithine decarboxylase (ODC) activity of rat intestines, liver, and brain was found to vary dramatically as animals develop and age. Unusually high activity was present in the small intestines of adult animals. The ODC activity of the small intestines approximated that of fetal tissues and of regenerating rat liver. Putrescine, spermine, and spermidine levels of fetal and adult animal tissues were determined. In all tissues but the stomach mucosa, high putrescine levels correlated with high IDC activity. However, the total polyamine concentrations of the stomach and colon could not be correlated with ODC levels, and no simple relationship between polyamine levels of ODC levels and cellular proliferation in the gut was found.