Androgen and Estrogen Binding in Male Guinea Pig Accessory Sex Organs1

Abstract

Following the i.v. administration of [3H]testosterone to adult male guinea pigs, the seminal vesicle epithelium contained the highest concentration of the reduced androgen, [3H]dihydrotestosterone, followed in order by the the prostate, seminal vesicle muscle and non-sex accessory tissue. Following i.v. injection of [3H]estradiol, the sex accessory tissues also accumulated this steroid in excess of certain other tissues, but within the seminal vesicle, higher concentration of [3H]-estradiol were recovered from the muscle than the epithelium. Examination of the in vitro cytosol binding of [3H]dihydrotestosterone revealed that of all tissues examined from the castrate guinea pig, the seminal vesicle epithelium contained the greatest amount of saturable [3H]dihydrotestosterone binding. Examination of the steroid specific nature of [3H]-dihydrotestosterone binding in the cytosols of the prostate and seminal vesicle epithelium and muscle revealed an order of competitor activity in all 3 tissues of dihydrotestosterone > testosterone > estradiol and progesterone > estrone > estriol. Quantification of [3H]estradiol binding in the cytosols from various tissues revealed that the seminal vesicle muscle contained the greatest amount of saturable [3H]estradiol binding, and that the binding of [3H]estradiol in the seminal vesicle epithelium, seminal vesicle muscle and prostate was also highly steroid specific. The order of steroid competitor activity for cytosol [3H]estradiol binding in all 3 tissues was estradiol 17.beta. > estrone estriol > dihydrotestosterone > cortisol and progesterone. Comparative effects of castration and estradiol treatment of castreate male guinea pigs on the apparent function of the sex accessory organ revealed that castration produced much greater regression of the epithelium than muscle, and estradiol replacement caused a rather selective growth of the fibromuscular component of sex accessory organs. These studies are in accord with the concept that sex accessory organ epithelium is highly sensitive to androgen but the interesting possibility is raised that if hormonal regulation of sex accessory fibromuscular tissue exists, it may be primarily estrogenic.