Effect of intrauterine application of oestradiol-17  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.

Maternal Recognition of Pregnancy in Swine. I. Minimal Requirement for Exogenous Estradiol-17β to Induce Either Short or Long Pseudopregnancy in Cycling Gilts1

“…The same daily dose of EB, administered by intrauterine infusion on Days 11 through 14, yielded similar results, with SPP induced in 2 of 6 gilts. Placement of intrauterine silastic beads containing E 2 , EB, or E 2 plus prostaglandin E 2 (PGE) into gilts on Day 10 produced inter-estrous intervals similar to those reported in experiments 2 and 3 [16]. Utero-ovarian venous and systemic E 2 concentrations were elevated to Day 14 or 15.…”

“…Previously, 3 estrogentreated gilts were observed to have an inter-estrous interval over 50 days (mean = 73.7 + 24.2 days) with 1 not returning to estrus by 365 days [16]. In a similar study, a mean inter-estrous interval of 92.0 11.2 days was reported [4].…”

“…tervals in other gilts. Two of four gilts injected with 3 mg Is remained elevated for 5 to 7 diethylstilbestrol on Day 16 (Day 1 = estrus) of the cycle g EV per day for 5 days [16]. displayed hastened estrus, while the other two gilts did not s were elevated for at least 72 return to estrus by 26 or 47 days.…”

“…Estrogen treatments that induce pseudopregnancy by intrauterine infusion are similarly effective when injected peripherally. Intrauterine administration of estrogen was found to induce pseudopregnancy only when dosages were large enough to elevate systemic estrogen concentrations [13,16,17]. However, an intrauterine E 2 dose that was apparently not sufficient to induce pseudopregnancy decreased uterine prostaglandin F (PGF) release [8].…”

Pre- and post-mating dietary supplements of folic acid and uterine secretory activity in gilts

“…The other horn was flushed with 20 mL of PBS within 1 h after slaughter according to a method described by Laforest and King (1992) and validated for day 12 of gestation by . The solution was introduced at the oviductal end using a blunt needle and a syringe.…”