Subcellular location of androgen receptor in rat prostate, seminal vesicle and human osteosarcoma MG-63 cells

Location of the androgen receptor (AR) before and after dihydrotestosterone (DHT) administration was studied in 6 castrated and 2 normal male rats, as well as in MG-63 human osteosarcoma cell culture. Two days after castration, rats were injected with DHT and sacrificed 0, 6 and 24 h later. Cryosections of ventral prostate and seminal vesicle were stained with a polyclonal anti-AR antibody. Cultured MG-63 cells were also stained similarly. The intensity of immunoreaction was measured semiquantitatively by computer-assisted image analysis. In both normal and castrated rats, a positive reaction was seen mainly in the nuclei of epithelial cells and stromal cells of the prostate and seminal vesicle, as well as in those of smooth muscle cells of the seminal vesicle. AR immunoreactivity was up-regulated by DHT, it decreased clearly in both organs after castration. Nuclear AR and its up-regulation by androgen were also seen in MG-63 cells. At the immunoelectron microscopy, silver enhanced gold particles were predominantly found in the heterochromatin of cell nuclei. Treatment with DHT caused a decondensation of the heterochromatin and AR was more dispersed. Thus, AR appears to be nuclear independently of the ligand.