EFFECT OF STEROIDAL HORMONES ON BINDING OF 17BETA-ESTRADIOL BY MOUSE UTERUS AND VAGINA

Surviving uteri, vaginae and occasionally pieces of the diaphragm from immature mice were incubated with tritium-labelled 17β-estradiol. After an uptake-washing procedure the uterus and vagina contained 30-40 times more radioactive 17β-estradiol than the diaphragm on a wet-weight basis. The natural estrogens 17β-estradiol, estrone and estriol reduced the binding of radioactive 17β-estradiol in the uterus and vagina but not in the diaphragm. Estrone and estriol were about 10 times less potent than 17β-estradiol in this respect. The estrogens showed an apparent affinity for binding in the vagina which was 3-4 times higher than that for the uterus. Testosterone at molar excesses of 104-105 slightly reduced the binding of 17β-estradiol in the uterus and vagina, while progesterone or hydrocortisone in the same concentrations showed no effect. Pretreatment with testosterone or 17β-estradiol in vivo increased wet weights and the binding capacity for 17β-estradiol of the uterus and vagina while progesterone only increased wet weight and binding capacity of the uterus. Hydrocortisone had no effect whatsoever. © 1968.