Elevated levels of ornithine decarboxylase and polyamines in the kidneys of estradiol-treated male hamsters

The effects of 17 beta-estradiol (E2) on the levels of ornithine decarboxylase (ODC), S-adenosylmethionine decarboxylase (SAMDC), and of the polyamines putrescine, spermidine and spermine in the kidneys of castrated male hamsters were determined. The i.p. injection of E2 into male hamsters led to renal ODC levels three times above the control levels 6--12 h after treatment. Similarly, the renal ODC levels in hamsters treated with chronic doses of E2 for 60--180 days were 1.5--1.9 times the corresponding enzyme levels in control, sham-operated animals. With a series of estrogen analogues, there was a direct correlation between the rise in renal ODC in vivo and the binding to renal estradiol receptor sites in vitro. The hamster kidney levels of the polyamines putrescine, spermidine and spermine all declined during the 180-day experimental period. A single i.p. injection of E2 led to a 70% increase in renal SAMDC activity 12 h after treatment. However, the administration of E2 for 180--270 days was without effect on the normal age-dependent decline in SAMDC levels noted in kidneys. These results indicate that, like other carcinogens and promoters, E2 increases the levels of ODC and of polyamines in its target tissue and that the rise in ODC is mediated by a specific estradiol-binding protein.