Prostaglandin H synthase activity in the sheep placenta during cortisol-induced labor at 128-131 days of gestation and during spontaneous delivery at term

J. Wimsatt, P. W. Nathanielsz

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

This study investigated whether the prostaglandin H synthase (PGHS) enzyme activity of sheep fetal placental cotyledon can be induced by cortisol at 128-131 days of gestation (dga) as compared to gestational age matched controls, before PGHS's normal gestational increase would occur (experiment 1). This study also investigated whether active PGHS is diminished following prostanoid synthesis in the labor process (experiment 2). A PGHS activity assay was employed in which PGE2 product was measured under initial velocity conditions. Labor was induced before term by continuous infusion of 10 mg of cortisol succinate per day (day 1) followed by 15 mg per day (days 2-4, or until delivery) of cortisol succinate administered through the fetal saphenous vein. Cotyledonary tissue was collected from sheep at term (142-145 dga), as judged by the absence of labor-type myometrial electromyogram (EMG) activity, and during cortisol induction at 128-131 dga. Tissue was also collected from term laboring animals immediately after fetal delivery while the fetus was still attached to the umbilicus and before placental delivery. At 128-131 dga, cortisol had no significant effect on PGHS activity as compared to gestational age matched saline-infused controls; thus, it is unlikely that cortisol directly induces PGHS. In experiment 2, normal progression of active spontaneous labor led to a significant diminution of PGHS activity (p < 0.05) that may be partially explained, based on thin-layer chromatography (TLC) results, as a significant decrease in PGE2 (p < 0.05) production coincident with a lesser compensatory increase in PGD2 (p = 0.06) output.

Original languageEnglish (US)
Pages (from-to)53-58
Number of pages6
JournalProstaglandins, Leukotrienes and Essential Fatty Acids
Volume53
Issue number1
DOIs
StatePublished - Jul 1995
Externally publishedYes

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology

Fingerprint Dive into the research topics of 'Prostaglandin H synthase activity in the sheep placenta during cortisol-induced labor at 128-131 days of gestation and during spontaneous delivery at term'. Together they form a unique fingerprint.

  • Cite this