Functional properties of isolated stroma and epithelium from rat ventral prostate during androgen deprivation and estrogen treatment.

To identify the functional activities of prostatic stroma under different hormonal conditions, isolated stroma and epithelium from rat ventral prostate (RVP, intact or one week castrated or estrogen-treated), were studied in metabolic labeling experiments. Using a semiquantitative stereological procedure, the relative proportion of the epithelial and stromal compartment was determined in situ. In addition, the distribution of the androgen receptor was visualized by in situ hybridization and by immunocytochemistry. In castrated animals protein biosynthesis of the stroma and epithelium exceeded the control value by a factor 7 and 5, respectively. In estrogen-treated animals protein biosynthesis was reduced, reaching only between one tenth and one fifth of the control value. The amount of stroma obtained from these animals was very low. These results were confirmed by stereological findings and indicate a differential regulation of prostatic stroma and epithelium after estrogen challenge and androgen deprivation. Estrogen receptor was induced in epithelium and stroma in estrogenized animals whereas the androgen receptor was reduced in experimental specimens. During estrogenization the biosynthetic activity of both stroma and epithelium is depressed, while estrogen responsivity of the epithelium in terms of estrogen receptor expression is increased. Androgen withdrawal results in active transformation of the gland through increased stromal biosynthetic activity and epithelial regression.