DETERMINATION OF PORCINE ENDOMETRIAL PHOSPHOLIPASE A(2) ACTIVITY AND DETECTION OF IMMUNOREACTIVE CYCLOOXYGENASE DURING THE ESTROUS-CYCLE AND EARLY-PREGNANCY

Experiments examined the characteristics and activity of phospholipase A(2) (PLA(2)) and examined the presence of immunoreactive cyclooxygen ase in endometrium of pigs during the oestrous cycle and early pregnan cy. Endometrial PLA(2) was calcium-independent and activity of the enz yme was greatest at a pH of 8.0. Activity of PLA(2) on Days 10, 12, 14 and 16 of the oestrous cycle did not differ (P>0.1) from activity on those days during pregnancy. During oestrus and early metoestrus (Days 0-3), cyclooxygenase was present in both glandular and surface epithe lium. After Day 10 of the oestrous cycle or pregnancy, staining for cy clooxygenase was less intense in the lower and middle uterine glands. However, the upper glandular epithelium near the surface epithelium st ained intensely. By Day 15 of the oestrous cycle or pregnancy, intense staining for cyclooxygenase appeared restricted to the upper uterine glands. These results indicate changes in localization of immunoreacti ve cyclooxygenase throughout the oestrous cycle and suggest that these are not related to altered secretion of prostaglandins (PGs) during e arly pregnancy. The stimulatory effects of porcine conceptus products on secretion of PGs during early pregnancy are apparently not associat ed with increased activity of endometrial PLA(2).