OESTROGEN ANTAGONISMS: TEMPORAL MODALITIES IN STEROID BLOCK OF OESTRONE-INDUCED CHANGES IN VAGINAL SMEARS OF MICE

Abstract

In an earlier paper simultaneous testosterone propionate (TP) was shown to inhibit the vaginal smear effects of oestrone given over two days to spayed female mice. Deoxycorticosterone acetate (DCA) and progesterone were inactive in that test. Oestrone was given at a dose of 2 ug and the other steroid at 1000 ug. If these same doses were given over a four day period, however, all three steroids blocked the oestrone-induced changes. In a series of tests in which the oestrone was given over four days and the blocker either in one or two day periods, TP was found to antagonize when administered with the early but not with the late oestrone injections. DCA was an inhibitor only when given with the late oestrone administrations. The period of progesterone activity was midway between that for TP and that for DCA, and overlapped each. These patterns of response were best discriminated when the blocker was administered in a single injection.