Alterations of histamine metabolism after injections of sex hormones in mice.

1. Urinary excretion of histamine in female mice was determined after the injection of oestradiol, progesterone or testosterone. Histamine excretion was increased by oestradiol but was not affected by progesterone. Testosterone administration, by contrast, effected a striking reduction of histamine excretion.2. After injection of oestradiol, the kidney histamine forming capacity was greatly elevated, but in the other tissues investigated no significant change occurred.3. Testosterone administered in vivo but not in vitro reduced the histidine decarboxylase activity of female mouse kidney to a small fraction of normal.4. On thin-layer chromatography, after extraction and coupling of the amines to 2,4-dinitrofluorobenzene, the amount of histamine and to a lesser extent, methyl histamine in urine was reduced after testosterone administration. On the chromatogram of urine from untreated mice, an unidentified yellow spot appeared and the quantity of this spot was increased during testosterone treatment.