Endometrial steroid receptors during decidualization in rhesus monkey (Macaca mulatta); their modulation by anti-oestrogen CDRI-85/287.

With a view to elucidating the hormonal control of decidualization in rhesus monkey, we studied the effects of CDRI-85/287, a potent anti-oestrogen, on endometrial steroid receptors in vivo and in vitro. Compound 85/287 was administered (i.m.) on days 8, 9 and 10 of steroid treatment cycle at a dose of 15 mg/monkey. Deciduoma was induced on day 16. Histological examination of endometrial tissue on days 24 and 30 of the cycle showed an apparent inhibition in uterine epithelial and subepithelial decidual cell plaque formation and a decrease in leukocytic infiltration into the stroma in anti-oestrogen-treated animals. As observed on day 24, a significant decrease in progesterone receptors (PR) (nuclear + cytosolic) was observed in the 85/287-treated group, whereas oestrogen receptor (ER) content remained unaltered. On day 30 total ER as well as total PR content was markedly reduced in treated animals. In-vitro results clearly demonstrated a competitive antagonism of 85/287 at the ER level only. The results are discussed in relation to the histological changes and modulation of steroid receptors, thereby suggesting the decidualization inhibitory activity of anti-oestrogen molecule 85/287 in primate species.