THE EFFECT OF PROSTAGLANDIN F2α ON PROGESTERONE, OESTRADIOL AND LUTEINIZING HORMONE SECRETION IN SHEEP WITH OVARIAN TRANSPLANTS

Authors:
  • WCW. A. Chamley
    W. A. Chamley
  • JBJoan M. Buckmaster
    Joan M. Buckmaster
  • MCM. D. Cain
    M. D. Cain
  • JCJ. Cerini
    J. Cerini
  • MCMildred E. Cerini
    Mildred E. Cerini
  • ICI. A. Cumming
    I. A. Cumming
  • JGJ. R. Goding
    J. R. Goding
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Abstract
SUMMARY The luteolytic properties of prostaglandin F2α (PGF2α) were studied in experiments on sheep with ovarian autotransplants. PGF2α was infused at the rate of 40, 10 and 2 μg/h for 4·0, 7·0 and 9·5–18·0 h respectively. At rates of 40 and 10 μg/h, progesterone secretion decreased to 50% of the control levels in 2·6 ± 1·4 h and fell to 8–30 μg/h within 36–52 h from the start of infusion. The onset of oestrus occurred 42–66 h after the infusions had started and a typical pre-ovulatory surge of luteinizing hormone (LH) was observed 52–66 h after infusing PGF2α. On occasions, this surge was accompanied by a brief peak of oestradiol-17β secretion and shortly thereafter ovarian steroidogenesis decreased to very low levels. In four sheep infused at a rate of 2 μg/h, peripheral progesterone values decreased gradually and only one animal returned to oestrus. It would seem that 2 μg/h is close to the minimum intra-arterial dose to cause luteolysis in the sheep.
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