Biosynthesis of histamine and putrescine in mice during post-natal development and its hormone dependence.

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.