Effects of ACTH on Adrenal RNA Synthesis1

Abstract

ACTH administration enhances the activity of adrenal homogenates and purified nuclei for incorporation of ATP-C14 and UTP-H3 into RNA. The effect on homogenate activity can be seen within 30 min. of ACTH administration, while the increase in purified nuclear activity is demonstrable somewhat later (after 4 hr.). Both effects appear to involve nuclear, DNA-dependent RNA synthesis. The homogenate effect persists despite the presence of high salt [(NH4)2SO4] concentrations, whereas the nuclear effect is either greatly narrowed or obliterated. Cycloheximide, an inhibitor of protein synthesis, completely blocks these effects of ACTH on RNA polymerase activity, suggesting a requirement for newly synthesized protein in this action of ACTH.