Dietary induction of ornithine decarboxylase in male mouse kidney

In male mouse kidney, ornithine decarboxylase (ODC) is induced after feedin g, and the induction depends on dietary protein content. 24 h after feeding with 50% casein-containing meal, ODC activity and amount of immunoreactive ODC protein increased more than 10-fold, ODC mRNA level increased 2-fold, and the ODC half-life extended 7-fold. The renal ODC induction after feedin g is, therefore, due mainly to stabilization of ODC protein. Urinary excret ion of putrescine increased in response to the ODC induction, but the renal polyamine contents scarcely changed. Consistently, the level of antizyme, a polyamine-inducible protein, determined as the ODC-antizyme complex level , scarcely changed after feeding, and the antizyme/ODC ratio in the kidney largely decreased, resulting in the stabilization of ODC protein. The prese nt results suggest that the strong excretion system of the kidney for newly synthesized polyamines enables renal ODC escape from antizyme-mediated fee dback regulation. (C) 1999 Elsevier Science B.V. All rights reserved.