Increased template activity of liver chromatin, a result of hydrocortisone administration.

Abstract

We have found that the administration of hydrocortisone to adrenalectomized rats increases the template activity of their liver chromatin for RNA synthesis. Such administration is known to cause a two- to threefold increase in rate of nuclear RNA synthesis in the liver (1,2). This increase is followed by an increase in the activities of a series of liver enzymes (3-5). Since the induction of these enzymes by hydrocortisone is abolished by simultaneous treatment with actinomycin D, it is clear that new RNA synthesis is required to support their formation (4,5). The increased rate of liver RNA synthesis caused by administration of hydrocortisone might in principle be due to changes in the template activity of the liver genetic material such as would accompany derepression of genes previously repressed. We shall show below that the administration of hydrocortisone does result in an increased availability of the genetic material for transcription.