Evidence for a Discriminatory Action of Androgenic Steroids on the Synthesis of Nucleolar Ribonucleic Acids in Prostatic Nuclei

Abstract

Testosterone, when injected into castrated rats, enhances the RNA-synthesizing activity of isolated prostatic nuclei. The nearest-neighbor frequency and base composition of RNA synthesized under the influence of androgens are completely different from those of control castrates. These effects of androgens in vivo can be abolished by low concentrations of actinomycin D added to the RNA-synthesizing systems or injected into the experimental animals. Only about 1% of total prostatic nuclear chromatin participates in the synthesis of RNA by prostatic nuclei of control castrated rats. The androgen-provoked enhancement of RNA-synthesis occurred at a separate and small (1% or less) region of nuclear DNA. The androgen-sensitive region of DNA has a strikingly high content of deoxycytidylyl (3′,5′)-deoxyguanosine dinucleotide sequence: 24 and 2 times, respectively, that of purified rat DNA and of the DNA region which functions as template for RNA-synthesis after animals are deprived of androgens. From the available information, it was concluded that androgen selectively enhanced the synthesis of RNA at nucleolar and/or perinucleolar regions of prostatic chromatin.