Concentrations of Prostaglandins E2and F2α and Their Relationship to Luteal function in Early Pregnant Ewes1

The effects of early pregnancy on tissue concentrations of prostaglandins E2and F2α: (PGE2and PGF2α) in the ovine endometrium, uterine vein and ovarian artery and on concentrations of PGE2and PGF2α in uterine venous plasma were examined. The relationship of concentrations of progesterone in jugular plasma to concentrations of PGE2and PGF2α in uterine venous plasma was determined. A uterine branch of the ovarian vein (UBOV) adjacent to an ovary bearing a corpus luteum was cannulated on day-14 postestrus in four pregnant and five nonpregnant ewes. Blood was collected from the UBOV of each ewe at 30-min intervals during each of five collection periods lasting approximately 1 hr (three blood samples per period; 15 per ewe). The first collection of blood from the UBOV was initiated at 0700 hr on day-15 postestrus. Each successive collection period was initiated approximately 6 hr after the start of the previous period. A jugular blood sample was taken from each ewe immediately after each sample from the UBOV. Samples of endometrium, uterine vein and ovarian artery were collected from each ewe on the morning of day-16 postestrus.The overall mean concentrations (ng/ml) of PGE2(.7 ± .1 vs1.2 ± .2) and PGF2α (3.3 ± .4 vs4.4 ± .9) in plasma from the UBOV and progesterone (3.1 ± .1 vs2.4 ± .1) in jugular venous plasma did not differ in pregnant and nonpregnant ewes. Profiles of PGE2did not differ with pregnancy status. Profiles of PGF2α differed over the 24-hr period studied (pregnancy status × collection period; P<.05), but not within the collection periods. Concentration of progesterone decreased significantly over time (P<.05) and collection periods (P<.01) in the nonpregnant ewes, but showed no covariance with concentrations of PGF2α and PGE2in pregnant or nonpregnant ewes.Concentrations of PGE2and PGF2α in endometrium and uterine venous tissue and PGF2α in ovarian arterial tissue were not affected by pregnancy status. In ovarian artery there tended to be less PGE2in nonpregnant than in pregnant ewes (P<.01).