Developmental aspects of polyamine-oxidizing enzyme activities in the mouse kidney. Effects of testosterone

In the present study developmental patterns of renal polyamine-oxidizing en zymes polyamine oxidase (PAO) and diamine oxidase (DAO) in male and female ICR mice were demonstrated. The effects of testosterone (10 mu g/100 mu g b ody weight) on renal PAO and DAO activities were also studied. The differen ces between sexes in both PAO and DAO activities were most clearly expresse d in the immature kidney. At the age of 20 days PAO and DAO activities were 1.52 fold (p < 0.01) and 1.75 (p < 0.02) respectively higher in male mouse kidney than in female. Maturational processes reflected in significant inc reases in polyamine- oxidizing enzyme activities mainly in female mouse kid ney, comparable with the gain in the kidney wet weight. Our data show that testosterone is able to influence renal PAO and DAO activities in addition to the well-known stimulation of polyamine biosynthesis. The hormonal effec ts were sex and age dependent. The influence of testosterone on renal PAO a ctivity was mainly age dependent. The slight stimulation of renal PAO activ ity observed in 20- and 50-day old mice, 24 h after testosterone administra tion, change with a decrease in the enzyme activity at the age of 70 days. The effects of testosterone on renal DAO activity were mainly sex dependent . Testosterone caused stimulation of DAO activity with a very close magnitu de (nearly twice) in female mouse kidney, independently of the age of mice. In contrast, in male mice the hormone treatment resulted in a statisticall y significant increase in renal DAO activity at the age of 70 days (1.3 fol d, p < 0.05) only. It could be suggested that our data indicate the differe nt contribution of renal PAO and DAO in androgen regulation of polyamine le vels, depending on sex and the stage of the postnatal development.