title: Circulating oestrogen concentrations during pregnancy in the African elephant (Loxodonta africana).
abstract: Oestrone, oestradiol-17 beta and oestriol were measured in plasma samples from non-pregnant and pregnant African elephants shot in the wild. Enzymic hydrolysis of plasma showed that approximately 90 and 96% of the total (i.e. conjugated plus unconjugated) concentrations of oestrone and oestradiol-17 beta, respectively were represented by conjugated hormones. Unconjugated oestrogens remained low (less than 50 pg ml) in all samples, with no distinction between non-pregnant and pregnant animals. Levels of total oestrone during pregnancy varied between 160 and 594 pg/ml but were not significantly different from non-pregnant values. Total oestradiol-17 beta concentrations were significantly elevated during pregnancy (P less than 0 X 01) and, despite considerable individual variation (193-1428 pg/ml), were consistently higher than non-pregnant values after 6 months of gestation. The elevated levels of oestradiol-17 beta resulted in a reversal of the total oestradiol-17 beta: oestrone concentration ratio at about 6 months of pregnancy. Concentrations of total oestriol did not exceed 103 pg/ml. An indirect method of measurement indicated that oestradiol-17 beta sulphate was probably the most abundant circulating oestrogen during pregnancy in the African elephant.
mesh_terms: D000818:Animals; D004606:Elephants / Q000097:blood*; D004958:Estradiol / Q000097:blood; D004964:Estriol / Q000097:blood; D004967:Estrogens / Q000097:blood*; D004970:Estrone / Q000097:blood; D005260:Female; D011247:Pregnancy; D011270:Pregnancy, Animal
chemical_list: D004967:Estrogens; D004970:Estrone; D004958:Estradiol; D004964:Estriol