An evaluation of the role of polyamines in different models of kidney hypertrophy in mice.

The role of ornithine decarboxylase (ODC) and polyamines in kidney hypertrophy is controversial. Since part of this controversy could be related to differences in the model system used by the different authors, we studied the changes in renal ODC and polyamines in six different models of kidney hypertrophy in mice, including compensatory renal hypertrophy produced by unilateral nephrectomy, experimental diabetes, potassium depletion and treatment with hormones such as testosterone, thyroxine and fluorocortisone. Only in the case of renal hypertrophy produced by testosterone administration was there a significant increase in ODC activity and putrescine content in the kidneys. However, the concomitant treatment with difluoromethylornithine (DFMO), an irreversible inhibitor of ODC, as a 2% solution in the drinking water completely abolished the increase of renal ODC, but the kidney weights increased and other androgenic effects, such as the induction of renal beta-glucuronidase, were not affected. Moreover, DFMO-treatment did not prevent the kidney enlargement produced in other types of hypertrophy, even in the cases associated with hyperplasia. The present results support the premise that, at least in mice, the increase in ODC activity and polyamine biosynthesis is not required for kidney growth, and also that in most cases renal enlargement is not accompanied by any increase in the polyamine content.