Castration-induced Apoptosis in the Rat Prostate

Kim, Ki Kwon; Lee, Sang Sook

Abstract

This study was carried out to investigate the morphologic findings and process of castration-induced apoptosis in the rat prostate. The experimental group was treated with bilateral orchiectomy followed by sequential sacrifices at 1, 2, 3, 4, 5, 6, 7 days and 2, 3 weeks (6 rats, respectively). Ventral prostate was extirpated and examined by light microscopic and immunohistochemical, ultrastructural observation. Apoptotic index increased by 4 days after castration and decreased thereafter. ApopTag stain revealed brownish granular pattern in the nucleus of apoptotic cells. DNA fragmentation rate was 0.5% in the control group and began to increase by 1 day after castration and reached to 11.1% by 4 days and decreased thereafter. PCNA stain showed brownish granular pattern in the nucleus of some epithelial cells of the prostatic glands. PCNA labelling index was 2.4% in the control group and reached peak by 3 days after castration and decreased thereafter. Electron microscopically, there was chromatin condensation with margination toward the nuclear membrane by 1 day after castration. Also noted were condensation of cytoplasm, dilatation of RER and nuclear fragmentation. Apoptotic bodies were formed and phagocytosed by adjacent cells and some apoptotic bodies were found in the lumen of acini. Based on these results, it can be concluded that castration-induced prostatic involution is the result of apoptosis. Detection of DNA fragmentation with ApopTag is a more a accurate method to identify not only apoptotic body formation itself but also the previous step of apoptotic body formation. PCNA labelling index to identify the cellular proliferation seems to play an active role in the early step of apoptosis and be a good tool for investigation of apoptosis.