ARGININE AND ORNITHINE METABOLIZING ENZYMES IN TESTOSTERONE-INDUCED HYPERTROPHIC MOUSE KIDNEY

Administration of testosterone to female mice causes hypertrophy of th eir kidneys with spectacular induction of ornithine decarboxylase and significant increase in the level of putrescine. We tried to find out whether testosterone treatment affects also the renal activities of en zymes participating in the formation and utilization of ornithine, spe cifically arginase and ornithine aminotransferase, and whether they ar e dependent on putrescine level. Swiss, CFW, DBA2 or F1 (CFW x DBA2) f emale and male mice were injected with testosterone (125 mg/kg) or CB 3717 (100 mg/kg). DFMO was applied in the drinking water. The activiti es of the enzymes were determined 24 hr or 5 days after administration of CB 3717 or testosterone, respectively. Renal activities of ornithi ne decarboxylase (ODC), arginase and ornithine aminotransferase (OAT) were found to be sex-differentiated. The highest activity of ODC was c haracteristic for the kidneys of males, whereas those of arginase and OAT for the kidneys of females. In the kidneys of testosterone-treated female mice a decrease (50%) of OAT, and a significant increase of ar ginase activities (up to 200%), were observed. In the males these chan ges were less pronounced. DFMO, which completely inhibited the activit y of renal ODC, did not influence significantly the testosterone-induc ed arginase and the testosterone-decreased OAT. Arginase and OAT, in c ontrast to ODC, were not changed in CB 3717-induced hyperplastic kidne y. The study showed testosterone-induced differential changes in the a ctivity of two enzymes involved in ornithine biosynthesis and cataboli sm which accompanied ODC induction in female mouse kidney. However ODC induction was not a prerequisite for these enzymatic changes as they did not follow ODC activation by CB 3717, and were not affected by DFM O, a specific inhibitor of ODC.