EFFECTS OF CASTRATION AND ANDROGEN REPLACEMENT ON ACID PHOSPHATASE ACTIVITY IN THE ADULT RAT PROSTATE GLAND

Abstract

Acid phosphatase (EC 3.1.3.2) activity was examined for its possible utilization as a biochemical marker for the profound changes that occur in the prostate gland after castration. Tissue filtrates were prepared from the prostate glands of mature male rats at various times after castration. The acid phosphatase activity was characterized by polyacrylamide gel electrophoresis and the percentage inhibition in the presence of tartrate. Prostatic acid phosphatase from mature rats has been shown to have two bands of activity, a lysosomal acid phosphatase and a secretory acid phosphatase. After castration, there was a loss of the secretory acid phosphatase from gel electrophoresis patterns by day 5 and a corresponding rise in the percentage inhibition by tartrate from the normal value of 43·2% to a maximum of 55·4% on day 7. Between days 7 and 15 there was a linear decrease in the percentage inhibition by tartrate, but after day 15 the value did not change significantly from 31·1% After castration, the specific activity of the uninhibited enzyme increased from a normal basal level of 2·16 μmol h−1 mg protein−1 to a maximum on day 7 of 8·10 μmol h−1 mg protein−1. After this time, the specific activity decreased slowly until it reached a normal level on day 21. Intraperitoneal administration of testosterone, 5α-dihydrotestosterone or 5α-androstane-3α,17β-diol at a dose of 2 mg/day and starting immediately after castration prevented the changes in percentage inhibition by tartrate and the loss of the secretory band of acid phosphatase. Administration of these androgens from day 7 after castration led to a decrease in the percentage inhibition from 50·1% to a minimum of 31·5% before the level returned to the normal value found in the mature rat. The secretory band of acid phosphatase, which was not present in gels at day 7, reappeared after 8–11 days of treatment with androgens. Of the androgens used,5α- androstane-3α,17β-diol was the most potent.