title: Effect of intrauterine application of oestradiol-17 beta and prostaglandin E-2 on the porcine oestrous cycle and uterine endocrinology.
abstract: Silastic beads were inserted into the uterine lumen on Day 10 after oestrus. Gilts received beads containing oestradiol-17 beta only, oestradiol benzoate, or oestradiol-17 beta+prostaglandin (PG) E-2. Oestrous cycles were slightly longer in treated than in untreated pigs (20.2 +/- 0.4 days), and durations were 22.6 +/- 1.3, 26.2 +/- 1.7 and 23.2 +/- 1.8 days for oestradiol-17 beta, oestradiol benzoate and oestradiol-17 beta+PGE-2 treatments, respectively (P greater than 0.05). Thus, PGE-2 and an oestrogen such as oestradiol benzoate that persist for a longer period cannot prolong the cycle more than oestradiol-17 beta alone. Additional cyclic gilts underwent similar treatments with beads containing oestradiol-17 beta, oestradiol-17 beta+PGE-2 or cholesterol, and cannulation of one utero-ovarian vein on Day 10. Blood samples were collected from the catheter every 15 min from 08:00 until 11:00 h and from 20:00 until 23:00 h for 5 consecutive days starting the day after surgery and peripheral plasma samples were also collected daily. On Day 16, beads containing oestradiol-17 beta were surrounded by endometrial folds whereas cholesterol beads were free. Concentrations of plasma progesterone did not vary significantly from Days 11 to 16 in gilts treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2, but decreased in cholesterol-treated gilts. Concentrations of plasma oestrone and oestradiol-17 beta were more than ten times higher in gilts treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2 than in cholesterol-treated gilts on the day after bead insertion, but decreased rapidly to values comparable to those in cholesterol-treated gilts by Day 14. In contrast, concentrations of oestrone sulphate remained high until Day 16. Concentrations of PGE-2 in the utero-ovarian vein plasma did not differ (P greater than 0.05) between treatments but those of PGF-2 alpha were higher (P less than 0.004) in gilts treated with cholesterol than in those treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2. It is postulated that insufficient oestradiol-17 beta is released by the beads toward the end of a 'recognition period' to prolong the cycle for more than 3-6 days.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, Ontario, Canada.
authors.forename: J P
authors.initials: JP
authors.lastname: Laforest
authors.forename: G J
authors.initials: GJ
authors.lastname: King
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology*; D004958:Estradiol / Q000378:metabolism / Q000494:pharmacology*; D004970:Estrone / Q000378:metabolism; D004971:Estrus / Q000187:drug effects*; D005260:Female; D003341:Luteolysis / Q000187:drug effects; D011374:Progesterone / Q000378:metabolism; D013552:Swine / Q000502:physiology*; D014599:Uterus / Q000187:drug effects* / Q000378:metabolism
chemical_list: D004970:Estrone; D011374:Progesterone; D004958:Estradiol; D002784:Cholesterol; D015232:Dinoprostone