Effects of prostaglandin E1 (PGE1) on estradiol-17 beta induced luteolysis in the nonpregnant ewe.

Nonpregnant ewes were assigned as they came into estrus to one of the following randomized treatment groups: 1) Vehicle (1 ml corn oil) + Vehicle (buffer), 2) Estradiol-17 beta + Vehicle (buffer) or Estradiol-17 beta + PGE1 in buffer. Ewes were unilaterally ovariectomized on day 8 postestrus and an intrauterine cannula was installed in the uterine horn adjacent to the remaining luteal-bearing ovary. Buffer of PGE 1 (500 micrograms) in buffer was infused intrauterine every 4 hours from day 8 through day 15. Luteolysis was initiated by giving an intramuscular injection of estradiol-17 beta (500 micrograms) on days 9 and 10. Chronic intrauterine infusions of PGE1 maintained jugular progesterone through day 15 and weights of corpora lutea and progesterone in corpora lutea on day 15 although luteolysis was initiated by estradiol. It is concluded that chronic intrauterine infusions of PGE1 can prevent an estrogen-induced premature luteolysis.