title: Metabolism of oestradiol-17 beta and progesterone in the white rhinoceros (Ceratotherium simum simum).
abstract: 14C-Labelled oestradiol-17 beta and progesterone (50 mu Ci each) were injected i.v. into an adult female white rhinoceros and all urine and faeces collected separately over the next 4 days. The total recovery of injected label was 61%, 25% being present in the urine and 36% in the faeces. Of the radioactivity recovered, 69% was excreted on Day 2 of the collection period. Repeated extraction of samples obtained on Day 2 showed that, of the radioactivity in faeces, 92.4% was associated with unconjugated steroids whereas in the urine the proportion of conjugated and unconjugated steroids were similar (41.2% and 51.4% respectively). After phenolic separation of urinary steroids, HPLC followed by derivatization and recrystallization techniques identified progesterone as the major component of the unconjugated portion with 4-pregnen-20 alpha-ol-3-one as the principal metabolite in the conjugated fraction. Pregnanediol was not present. Oestrone appeared to be the most abundant oestrogen metabolite with smaller but significant amounts of oestradiol-17 beta and oestradiol-17 alpha in the unconjugated and conjugated fractions respectively. Small amounts of progesterone were found in  the faecal extract in which the radioactivity consisted mainly of oestradiol-17 alpha and oestradiol-17 beta. The results have established the major excreted metabolites of oestradiol-17 beta and progesterone in the white rhinoceros and the development of more appropriate assay methods for monitoring ovarian function in African rhinoceroses should now be possible.
authors.affiliation: Institute of Zoology, Zoological Society of London, UK.
authors.forename: J E
authors.initials: JE
authors.lastname: Hindle
authors.forename: J K
authors.initials: JK
authors.lastname: Hodges
mesh_terms: D000818:Animals; D004958:Estradiol / Q000378:metabolism*; D004966:Estrogens, Conjugated (USP) / Q000652:urine; D004970:Estrone / Q000652:urine; D005260:Female; D010527:Perissodactyla / Q000378:metabolism*; D011284:Pregnenolone / Q000652:urine; D011374:Progesterone / Q000378:metabolism*
chemical_list: D004966:Estrogens, Conjugated (USP); D004970:Estrone; D011374:Progesterone; D004958:Estradiol; D011284:Pregnenolone