Studies on the mechanisms of action of XXXX antagonists.

@entity840 @entity6002 @entity1420 @entity3009
Antigestagens of RU-38.486-type were investigated in different pregnancy models reflecting either "endometrial" or "myometrial" effects. All antigestagens were found effective inhibitors of nidation in @entity840 . This was evidence for a role of embryonic @entity1420 in the earliest events of nidation. No comparable inhibition could be obtained by ovariectomy. A more complex pharmacology was found around day 43 p.c. when the abortion was brought about by expulsion. RU-38.486 had marginal activity only. Antigestagens with reduced anti-glucocorticoid activity tended to induce abortions more effectively and faster. Some antigestagen- @entity3009 combinations were found of extreme abortifacient activity. Surprisingly it seemed that anti-glucocorticoid properties in addition to (or rather than) antigestagenic activities bring about this synergism with @entity3009 . The employed @entity840 model for pregnancy termination thus characterized two types of antigestagens: ideal ones for monotherapy or combined use with @entity3009 , respectively. Antigestagens induced a highly sensitive myometrium to @entity3009 -stimulation ( @entity6002 ) and a marked softening and dilatation of the cervix. Antigestagens perfectly prime the genital tract for oxytocic stimuli, they do not overcome the arrested uterine @entity3009 -secretion of the pregnant uterus at the same time.
