Acid ribonuclease in rat prostate during castration-induced involution

The activity of acid ribonuclease (RNase) in the ventral prostate of rats was measured at different intervals following castration. The specific activity (units/mg protein) in the prostate of non castrated rats was relatively low and increased gradually, though not significantly, through the first 3 days after castration. The enzyme activity reached a maximal level between Days 5 and 7 (P<0.01), then decreased gradually, and returned to the precastration level by Day 14. Subcutaneous injection of actinomycin D at 50 μg/day to castrated rats for 4 or 5 consecutive days retarded the rate of prostatic regression and was accompanied by a significant reduction in RNase activity in the prostate. These results indicate that elevated specific activity of RNase coincided with the period of rapid prostatic regression and that this elevation in enzyme activity can be suppressed by actinomycin D.