EFFECT OF HORMONES AND ANTIHORMONES ON PHOSPHOLIPASE A(2) ACTIVITY INHUMAN ENDOMETRIAL STROMAL CELLS

Phospholipase A(2) activity was studied in isolated human endometrial predecidual cells, and in human endometrium collected from day 19-23 o f the menstrual cycle, by performing a radiochemical assay. Phospholip ase A(2) activity on day 20 was significantly higher than other days ( P < 0.001), and the activity was found to gradually decrease after day 20 of the menstrual cycle. The effects of the hormones estradiol and progesterone, and antihormones tamoxifen and RU 486, were studied on t he phospholipase A(2) activity in isolated predecidual stromal cells. Estradiol produced a significant stimulatory effect (P < 0.001) on pho spholipase A(2) activity in predecidual cells, and this effect was ant agonized by tamoxifen. The combination of estradiol and tamoxifen was significantly different from estradiol alone (P < 0.001), but not from tamoxifen alone. RU 486 alone significantly increased (P < 0.001) pho spholipase A(2) activity in predecidual stromal cells. However, proges terone had no effect on phospholipase A(2) activity in predecidual str omal cells.