Expression of cyclooxygenase-1 and -2 in Ovine Endometrium During the Estrous Cycle and Early Pregnancy

Endocrinology. 1997 May;138(5):2163-71. doi: 10.1210/endo.138.5.5148.


In this study we investigated the expression of the two cyclooxygenases, cox-1 and -2, in sheep uterine tissues during the estrous cycle and early pregnancy. We identified the cox-2 isoform in the ovine uterus by Western blot and demonstrated that the two cyclooxygenases exhibited different patterns of expression. Cox-1 was expressed at steady state levels in the endometrium during the estrous cycle and comparable stages of pregnancy. In contrast, cox-2 was highly and transiently expressed from days 12-15 of the estrous cycle and declined thereafter to undetectable levels. Endometrium from early pregnant ewes showed a similar pattern of cox-2 expression, although there was a slower decrease beyond day 15. Immunohistochemical studies demonstrated that cox-1 was localized in both epithelial and stromal cells, whereas cox-2 was localized solely in the luminal epithelium and to a lesser extent in the superficial glands. Treatment of ovariectomized ewes with steroids indicated that expression of cox-1 remained at constant levels whatever the treatment. In contrast, endometrial cox-2 was highly induced by a 10-day progesterone treatment. Estradiol slightly increased cox-2 expression but only after progesterone priming. Collectively these results suggest that the developing ability of the uterus to synthesize PGs is due to the induction of cox-2.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Blotting, Western
  • Cyclooxygenase 1
  • Cyclooxygenase 2
  • Dinoprost / metabolism
  • Endometrium / enzymology*
  • Estradiol / pharmacology
  • Estrus / physiology*
  • Female
  • Immunohistochemistry
  • Isoenzymes / analysis
  • Isoenzymes / metabolism*
  • Ovariectomy
  • Pregnancy
  • Pregnancy, Animal / metabolism*
  • Progesterone / pharmacology
  • Prostaglandin-Endoperoxide Synthases / analysis
  • Prostaglandin-Endoperoxide Synthases / metabolism*
  • Sheep


  • Isoenzymes
  • Progesterone
  • Estradiol
  • Dinoprost
  • Cyclooxygenase 1
  • Cyclooxygenase 2
  • Prostaglandin-Endoperoxide Synthases