INCREASED LEVELS OF CLUSTERIN MESSENGER-RNA IN THE VENTRAL PROSTATE OF THE AGING RAT ARE ASSOCIATED TO INCREASES IN CUBOIDAL (ATROPHIC) CELL-POPULATION AND NOT TO CHANGES IN APOPTOTIC ACTIVITY

In the ventral prostate of the intact rat, clusterin mRNA is expressed in a small population of cuboidal epithelial cells undergoing apoptos is, but not in the columnar cells comprising the vast majority of the glandular epithelium. Upon castration, clusterin mRNA expression and a poptotic activity are turned off in the cuboidal cells and turned on i n the columnar ones. We show here that the progressive enhancements in the abundance of clusterin mRNA, occurring in the rat ventral prostat e upon aging, are based on increases of the cuboidal cells at the expe nse of the columnar ones. DNA fragmentation, a typical sign of apoptos is, assayed both by agarose gel electrophoresis and in situ staining, was undetectable in 3-month-old rats but was evident among the cuboida l cells of 24-month-old animals and columnar cells of 1-day castrates. The DNA content of the ventral prostate did not change significativel y between young and old rats, indicating that no increase in the rate of cell death occurs within the age interval examined. It is concluded that the enhancement in cuboidal cell population, the consequent augm ented accumulation of clusterin mRNA, and the increased frequency of D NA fragmentation that we have detected in the aging rat ventral prosta te are not directly related to the rate of apoptosis.