Oestrogen-anti-oestrogen interaction: effect of U11100A, MRL-41 (clomiphene) and U11555A on oestrogen induced uterine glycogen and protein synthesis in the rat during delayed implantation

Abstract

A comparative study of three non-steroidal anti-oestrogens (a dihydronaphthalene, UlllOOA; a diphenylindene derivative, U-11555A and MRL-41 (clomiphene) was made in order to study their mode of action and their interaction with oestrogen induced biochemical changes in the uterus. Pretreatment with UlllOOA, clomiphene or U11555A effectively blocked the oestrogen induced increase in uterine glycogen and protein synthesis. However, all the three compounds tested were found to be uterotrophic; clomiphene also increased uterine glycogen while U11555A showed a transient oestrogenic action in increasing uterine protein. Clomiphene and U11100A have been shown to inhibit the uptake of oestrogen at the receptor sites. Our results may be interpreted as indicating that pretreatment with these compounds (U11100A, clomiphene or U11555A) blocked the uterine receptor sites in such a manner so as to render ineffective the action of oestrogen administered subsequently.