The effects of the high affinity antiestrogen, H1285, on uterine growth and morphology

Experiments were performed to compare the agonistic and antagonistic properties of the high affinity antiestrogen, H1285, and the low affinity antiestrogens CI-628 and tamoxifen on rat uterine growth and morphology. Myometrial and stromal areas and endometrial epithelial cell heights were calculated. Whereas all antiestrogens displayed some degree of estrogenic response, only H1285 at 5 or 0.5 micrograms was an effective inhibitor of E2 induced proliferative responses in the myometrium, stroma, and endometrial epithelium. All antiestrogens caused tremendous endometrial hypertrophy.