Conversion of (4- 14 C)progesterone to androsterone by female rhesus monkeys (Macaca mulatta).

Abstract

SUMMARY Labelled progesterone was administered intravenously to five, adult female rhesus monkeys and urine and faeces were collected every 24 h. Excretion of radioactivity in urine occurred most rapidly in the first 24-h period and then declined exponentially. The excretion of radioactivity in faeces reached maxima during the 2nd, 3rd or 4th 24-h periods depending on the animal studied. 76–94% (mean 86%) of the radioactivity administered was recovered within 9 days, but small quantities continued to be excreted in urine up to 16 days after injection. Generally, greater amounts of radioactivity were recovered from faeces (41–57%) than from urine (26–48%). Using different hydrolytic and extraction procedures, some 50% of the radioactivity in urine was recovered in the neutral extracts. The major metabolite in urine was androsterone which accounted for 1·1–12·2% (mean 6·0%) of the progesterone administered. Pregnanediol was not an important urinary catabolite in this species. Differences in the extent to which progesterone is metabolized to C-19 compounds in macaques, baboons, great apes and man may reflect the phylogeny of a catabolic desmolase system in anthropoid primates.