1. Histidine decarboxylase and ornithine decarboxylase activities were determined in mouse kidney and liver during post‐natal development. 2. The content of histamine, putrescine, spermidine and spermine was examined in kidney and liver and in the urine of adult male and female mice. 3. Histamine formation by the kidney was high in both sexes when determined a few days after birth but decreased during weaning. Thereafter, a distinct sex difference was established in that in the female kidney the level of histidine decarboxylase rose several‐fold during adolescence while in the male the level was still further reduced. 4. Putrescine formation by mouse kidney was low in both sexes up to three weeks of age whereafter the amine formation in the male increased conspicuously whereas that of the female kidney remained low. 5. The observed sex differences in tissue enzyme activities were reflected in concomitant differences in the amount of the diamines excreted in the urine. 6. No correlation was found between the actual enzyme levels and the assayed tissue content of histamine, putrescine, spermidine and spermine. 7. Following gonadectomy, the activities of both decarboxylases were significantly altered. Ornithine decarboxylase activity of male kidney and histidine decarboxylase activity of female kidney were strikingly reduced. 8. In the mouse liver, the two decarboxylases displayed no changes comparable with that of the kidney during development.

Daily injections of testosterone propionate to castrated mice resulted in a striking increase in kidney weight. Renal putrescine rose sharply and the amounts of spermidine were also increased. The activity or ornithine decarboxylase was enhanced to values of more than 1 000 times the control level within a few days of testosterone substitution. A moderate and temporary increase in the activity of the putrescine-activated S-adenosyl-L-methionine decarboxylase was observed. Testosterone injections produced a large increase of renal RNA but only a minor change in DNA. It is apparent that in mice distinct alterations in polyamine metabolism occur during the development of renal hypertrophy induced by testosterone administration.

The catabolism of injected 14C‐putrescine was studied in mice treated with nandrolone phenpropionate, an anabolic steroid. The putrescine was rapidly metabolized; almost 50% of the injected radioactivity was recovered within 2 h as 14CO2 in the expired air. Considerable amounts of radioactive γ‐aminobutyric acid (GABA) and an unidentified compound were found in the kidney and in the urine in addition to radioactive putrescine, spermidine and spermine both in controls and nandrolone‐treated mice. Nandrolone elevated the concentration of endogenous putrescine in the kidney and urine, eightfold and twentyfold, respectively, and the concentrations of spermidine and spermine were also increased. After the injection of 14C‐putrescine the incorporation of 14C into spermidine was significantly increased in the kidney of mice receiving nandrolone.

Summary The urinary excretion of putrescine has been determined in female mice before and during repeated injections of testosterone. Testosterone administration effected a striking increase in the excretion of free putrescine. Ornithine decarboxylase (l‐ornithine carboxy‐lyase; E.C. 4.1.1.17) and histidine decarboxylase (l‐histidine carboxy‐lyase; E.C. 4.1.1.22) activities of mouse kidney and liver were examined. In the kidney, following testosterone administration, ornithine decarboxylase activity was found to be substantially elevated, whereas that of histidine decarboxylase was depressed. In the liver, by contrast, the activity levels of these enzymes were not significantly altered by testosterone treatment. The possibility of a functional interrelation between putrescine and histamine, via the two enzyme activities investigated, is discussed.

SUMMARY1. The urinary excretion of histamine, methylhistamine, putrescine, cadaverine, spermidine and spermine was examined before, during and after pregnancy in rats.2. During the last third of undisturbed pregnancy a distinct and steep rise occurred in the excretion of all the amines studied except spermine. The peak values were found a few days before the birth of the young. In spermidine excretion a second peak was observed one or two days after delivery.3. Before and during the first 2 weeks of gestation on a molar basis putrescine excretion was the greatest one. During the last trimester histamine was excreted in the largest amount.4. Under the influence of the diamine oxidase inhibitor aminoguanidine the general pattern of excretion of diamines and polyamines in pregnant rats remained essentially unchanged but the total amount excreted increased. Most conspicuous was the great elevation of urinary contents of putrescine and cadaverine.