DIFFERING PATTERNS OF ACID PHOSPHATASE AND CATHEPSIN D ACTIVITIES IN THE RAT VENTRAL PROSTATE GLAND DURING CASTRATION-INDUCED PROSTATIC INVOLUTION

Abstract

ABSTRACT The activities of acid phosphatase and cathepsin D in the rat's ventral prostate lobe were investigated under normal conditions and during castration-induced involution. The specific activities of the acid hydrolases were higher in the prostatic »tissue« fraction than in the »secretion« fraction of the gland, and the total activities of acid phosphatase and cathepsin D in the »secretion« were increased up to about 24 % and 8 %, respectively, of the activities in the whole lobe. During involution, the specific activities of both hydrolases in the tissue showed a rapid increase, while total activity and activity »per cell« (on a DNA basis) of acid phosphatase declined, while the total activity of cathepsin D remained essentially unaltered at first and ultimately decreased; the activity of cathepsin D »per cell« was first increased and later showed a slight decrease. Cycloheximide administration retarded the gross atrophy and decrease in protein and DNA content, and was associated with a lowered total, specific and »per cell« activity of cathepsin D, and an »increased« total activity of acid phosphatase. The observations are compatible with an increased de novo synthesis of cathepsin D and a decreased synthesis of acid phosphatase during prostatic involution. The findings were interpreted as indicating that in the ventral prostate lobe of the rat, acid phosphatase is in part a secretory (and hormonesensitive) enzyme, and in part a »conventional« lysosomal enzyme, while cathepsin D is predominantly an enzyme which is bound to conventional lysosomes.