THE UPTAKE OF LOCALLY APPLIED [6:7-3H]OESTRADIOL-17β BY THE VAGINA OF THE OVARIECTOMIZED MOUSE

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Abstract
SUMMARY: Locally applied [6:7-3H]oestradiol was taken up rapidly by the vagina, at a rate similar to that of oestrone. Levels of radioactivity in the tissue reached their highest value 1–3 min. after application, and thereafter dropped slowly to reach 20% of the injected dose at 12 hr. This is in contrast to the behaviour of oestrone, the tissue levels of which fell rapidly over the first ½ hr. It is suggested that this difference accounts for the relative biological activity of the two hormones in the vagina, and results from varying affinities for receptor sites associated with the initiation of vaginal growth. Evidence is presented that oestrone, oestradiol and oestriol have a common site of action. Dimethylstilboestrol (DMS) converted the retention pattern of oestradiol to one resembling that of oestrone, and it is suggested that this involves blocking of receptor sites. The results are discussed in relation to the mode of action of oestrogens.