[Regressive change in the rat prostate after castration. A study using histology, morphometrics and autoradiography...

The individual processes involved in involution of the prostate gland following androgen withdrawal are incompletely understood. The rat prostate was used to investigate cell loss (numeric atrophy), decrease in cell size (simple or cellular atrophy) and altered cell proliferation. The prostate gland was studied at various times after castration using histological, nuclear morphometric and 3-H-thymidine autoradiographic methods, as well as by measuring weight. Cell loss was determined by the proportion of apoptosis-bodies. Following castration a decreased formation of secretions and reduction in interstitial tissue fluid were observed, as well as reduced cell proliferation, which did not affect the weight, as the normal cell proliferation in all lobes of the prostate is extremely small. The nuclear size fell to 30%. The apoptosis index, i.e. cell loss, was considerable and reached a maximum in the coagulating glands on day 2, and in the other prostate lobes between day 4 and 8. After this time cell loss corresponded to that of control animals. Cell loss measured by apoptosis has proved to be reliable parameter of hormone-dependent regression of the prostate. The responsiveness of prostate carcinomas to hormone treatment can be tested possibly using alteration in the apoptosis index already some days after withdrawal of androgens.