Expression and degradation of rat androgen receptor following castration, testosterone replacement and antiandrogens administration: analysis by Western blot and immunohistochemistry.

To elucidate the autoregulation of androgen receptor (AR) by androgen and antiandrogen, Western blot analysis and immunohistochemical study were performed. Castration reduced the immunodetected AR content, and nuclear staining was lost without cytoplasmic staining. Testosterone (T) supplement restored AR content. Quick response of AR content restoring following single administration of T was observed 48 hours after castration. The recovery of AR content detected by Western blot under each condition was accompanied by recovery of the reduced unclear staining intensities in the epithelia. Neither steroidal nor non-steroidal antiandrogens, chlormadinone acetate and flutamide, altered the AR content in normal rat ventral prostate 5, 12, 24 or 48 hours after single administration. Furthermore, neither of the drugs at various doses altered AR levels 12 hours after single administration. In summary, the rat AR is upregulated by androgen. Single administration of antiandrogens have no effect on immunodetected AR content.