Biology of Reproduction, Vol 22, 827-831, Copyright © 1980 by Society for the Study of Reproduction

Acid Ribonuclease in Rat Prostate During Castration-Induced Involution

¹ Department of Urology, Northwestern University Medical School, Chicago, Illinois 60611

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 noncastrated 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.

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ACKNOWLEDGMENTS We thank Brigittee G. Mann from the laboratory of Dr. Neena B. Schwartz for her assistance on radioimmunoassay for serum testosterone, and Dr. Gordon Niswender for the supply of testosterone antiserum (#250). This study was supported by NIH grant (HD 11611), by the Edwin and Lucy Kretchmer Fund from Northwestern University Medical School, and by a grant from the Grainger Foundation.