title: Short and long phases of progesterone secretion during the oestrous cycle of the African elephant (Loxodonta africana).
abstract: Serum samples were collected from 3 mature female African elephants once each week for 15-18 months. Circulating concentrations of progesterone, oestradiol and LH were determined by radioimmunoassay (RIA). The LH RIA was validated by demonstrating parallel cross-reaction with partly purified elephant LH pituitary fractions. Changing serum progesterone concentrations indicated an oestrous cycle length of 13.3 +/- 1.3 weeks (n = 11). The presumed luteal phase, characterized by elevated serum progesterone values, was 9.1 +/- 1.1 weeks (n = 11). Two abbreviated phases of progesterone in serum lasting 2-3 weeks were observed in 2 elephants, indicating short luteal phases. Oestradiol concentrations in serum were variable, with no clear pattern of secretion. More frequent blood samples were collected during periovulatory periods and 9 distinct LH peaks were detected; all were followed by rises in serum progesterone concentrations. Periovulatory changes in progesterone and LH in sera correlated with external signs of oestrus and mating behaviour.
authors.affiliation: Department of Physiology, Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City 66103.
authors.forename: J D
authors.initials: JD
authors.lastname: Brannian
authors.forename: F
authors.initials: F
authors.lastname: Griffin
authors.forename: H
authors.initials: H
authors.lastname: Papkoff
authors.forename: P F
authors.initials: PF
authors.lastname: Terranova
mesh_terms: D000818:Animals; D004606:Elephants / Q000502:physiology*; D004958:Estradiol / Q000097:blood; D004971:Estrus / Q000502:physiology*; D005260:Female; D007986:Luteinizing Hormone / Q000097:blood; D011374:Progesterone / Q000097:blood / Q000378:metabolism*; D011863:Radioimmunoassay; D012636:Secretory Rate
chemical_list: D011374:Progesterone; D004958:Estradiol; D007986:Luteinizing Hormone