Action of testosterone on RNA synthesis in the rat uterus.

The effect of testosterone on transcription was investigated in the uterus of the ovariectomized rat. Testosterone rapidly depressed both RNA polymerase A and B activities for up to 2 h after administration. Thereafter, RNA polymerase A activity increased, reaching control values at 4 h, and remained constant. On the contrary, RNA polymerase B activity remained depressed at 6 and 18 h after the administration of testosterone. The cellular entities or mechanisms which testosterone uses to alter transcription in the cell nucleus remain to be determined.