Prostatic involution: Effect on androgen receptors and intracellular androgen transport

Abstract

In the regressing rat prostate gland the concentration of cytoplasmic receptor declines from a maximal level of 174 ± 24 fmoles/mg protein 1 day after orchiectomy and is virtually undetectable after 7 days. The results of tissue mixing experiments in which equal amounts of prostate from rats orchiectomized 1 day and 7 days previously are incubated and homogenized together indicate that at the latter time the prostate contains factors, presumed to be proteolytic enzymes, which can eradicate the binding of radioactive dihydrotestosterone to cytoplasmic receptor. In the apparent absence of cytoplasmic receptor, the capacity of the cell to transfer androgens into the nucleus is kept intact at a level 30–60% of the experimentally determined maximum, and the competence to form intranuclear receptor is preserved. However, the nuclear receptor observed 7 days after orchiectomy is smaller than the one observed 1 day after orchiectomy.