Effects of PGF on pig corpora lutea following administration on Day 9 of the estrous cycle

Alan J Conley, S. P. Ford

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

Before Day 12 of the estrous cycle, pig corpora lutea (CL) seemingly are refractory to the luteolytic effects of prostaglandin F2α (PGF). This study investigated functional and structural effects of PGF on pig CL during this refractory period. Nine gilts were unilaterally ovariectomized on Day 8 (first day of estrus = Day 0), and femoral arterial (FA) catheters were inserted. Gilts received 20 mg PGF or vehicle (saline) at 07:00 h on Day 9. After PGF or vehicle treatment, blood was collected hourly for 6 h, then twice daily (07:00 and 19:00 h) until the remaining ovary was removed at 07:00 to 08:00 h on Day 12. Progesterone had declined markedly in the FA by 3 h after PGF, but had returned to pretreatment levels by 19:00 h on Day 11. In the vehicle-treated group, increases in luteal weight, protein and DNA were observed (P < 0.05) from Day 8 to 12, while CL from PGF-treated gilts only exhibited increases (P < 0.05) in DNA. As a result of this reduced luteal growth, the protein to DNA ratio decreased in PGF-treated (18.1 ± 5.4%), but not in vehicle-treated gilts during this same period. Luteal progesterone content increased more (P < 0.05) from Day 8 to 12 in vehicle (89.7 ± 28.4%) than in PGF-treated gilts (23.5 ± 4.7%). Similarly, luteal progesterone concentration tended to increase in vehicle-treated (45.8±20.7%, P < 0.06), but not in PGF-treated gilts. Luteal characteristics in sham-operated control gilts were similar to those of vehicle-treated gilts on Day 12 of the estrous cycle. These data indicate that PGF administered to pigs on Day 9 of the estrous cycle transiently inhibits luteal function. Luteal composition at Day 12 was altered by PGF administration, but luteal growth continued from Day 8 to 12, possibly by increases in the numbers of small, non-steroidogenic cell types. Luteal growth in vehicle-treated gilts suggests that substantial development occurs in pig CL after Day 8 of the estrous cycle.

Original languageEnglish (US)
Pages (from-to)335-342
Number of pages8
JournalAnimal Reproduction Science
Volume24
Issue number3-4
DOIs
StatePublished - 1991
Externally publishedYes

ASJC Scopus subject areas

  • Animal Science and Zoology
  • Endocrinology
  • Food Animals

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