The oestrogenic potency in the mouse of several substances closely related to diethylstilboestrol and meso-hexoestrol

The effects of oestradiol, diethylstilboestrol, α,α′-dimethylstilbene-4,4′-diol (DMS), α-ethyl-α′-methylstilbene-4,4′-diol (MES), meso-hexoestrol, dl-hexoestrol, meso-butoestrol, dl-butoestroland erythro-α-ethyl-α′-methyl-4,4′-dihydroxybibenzyl (erythro-MEA) on the incorporation of tritiated uridine into uterine RNA were investigated. At 2 hr., valid relative potency estimates with oestradiol were obtained with all substances, and MES, erythro-MEA and meso-butoestrol were almost as potent as diethylstilboestrol and meso-hexoestrol. The time-course of the uridine response to the different substances varied markedly. Injections every 16 hr. of DMS, MES, dl-hexoestrol, meso-butoestrol and erythro-MEA elicited little uterine or vaginal growth, but small doses of these substances given every 4 hr. elicited considerable growth in both organs. It was concluded that the compounds tested were oestrogens and not pro-oestrogens.

The relative potencies of oestriol, oestradiol and oestrone on the uterus and vagina of the mouse

The effects of oestriol, oestradiol and oestrone on the uterus and vagina of the mouse have been investigated, by measuring changes in the incorporation of tritiated uridine into RNA, and in wet and dry organ weight. The time course of the uridine response to a single injection of oestriol differs markedly from that seen with single injections of oestradiol and oestrone. Oestriol has only a weak uterotrophic action in tests employing daily oestrogen injections, but when administered every 4 hr. in small doses it elicits as much growth in both organs as does oestradiol. The relative capacities of oestriol and oestradiol to sensitize the uterus to the induction of deciduomata by peanut oil are contrasted.

The effects of oestradiol and progesterone on the incorporation of tritiated uridine into the genital tract of the mouse

The pattern of changes in levels of uridine incorporation into uterine and vaginal RNA at different times after the commencement of daily injections of several dose combinations of oestradiol and progesterone has been determined. Progesterone does not antagonize the response to oestradiol in the uterus and vagina at 16 hr., but in the uterus augments the effects of lower doses of oestradiol. At 48 hr., progesterone eliminates the response to oestradiol in the vagina. The interaction in the uterus is more complex. At 47 hr., or later, relatively high levels of uridine incorporation into uterine RNA are maintained by the administration of either oestradiol alone, at doses of 27 ng. or more; or by oestradiol and progesterone together, at doses of about 6 ng. and 0·33 mg. respectively. In mice receiving intraluminal peanut oil as a decidual stimulus the sensitivity of the uterus to deciduoma formation is not well correlated with its ability to incorporate uridine into RNA.

The interaction in the immature mouse of potent oestrogens with coumestrol, genistein and other utero-vaginotrophic compounds of low potency

Interaction in the immature mouse of potent oestrogens with the weak utero-vaginotrophic (UV) compounds, coumestrol, genistein, dimethyl-stilboestrol, norethisterone acetate and megestrol acetate though sometimes additive at very low doses appeared to be essentially antagonistic at higher doses.

In particular, the weak oestrogens coumestrol and genistein, found in certain plants, markedly inhibited the UV action of potent oestrogens, e.g. oestradiol-17β, oestrone and diethylstilboestrol and this effect may account in part for the anti-oestrogenic activity of extracts of these plants.

Some differences in the ability of different oestrogens to promote uterine growth relative to vaginal growth were observed.