Effects of estriol on PGF2 alpha output by cultures of human endometrium and endometrial cells

We have shown that the rate of release of PGF2 alpha by monolayer cultures of epithelial cells from proliferative endometrium is markedly elevated by addition of estradiol to the medium. In cultures maintained in HAM F-10 medium containing charcoal stripped calf serum, estradiol (10(-8) M) increased the levels of PGF2 alpha several fold during the second and third days in culture. Similar responses were obtained with estradiol at 10(-10) M concentration. When this system was used to compare the effects of estradiol and estriol at equal concentrations (10(-8) M), similar elevation (10-16-fold) of PGF2 alpha levels were noted during 3 consecutive days in culture. When cultures of epithelial cells derived from secretory endometrium were used for these tests, estriol was as effective as than estradiol in elevating PGF2 alpha levels in the medium. When the effects of estradiol and estriol were compared using fragments of secretory endometrium in organ culture, the increases in PGF2 alpha levels noted in the medium were about equal (2- to 10-fold) for the two estrogens at the same concentration (10(9)-10(8) M). Exposure of the tissue to either estradiol or estriol for only 1 h resulted in increases in PGF2 alpha output for the following 3 days. These results clearly show that estriol is as effective as estradiol in stimulating PGF2 alpha output by human endometrial tissue.