Hormone-induced changes in liver DNA synthesis: effects of glucocorticoids and growth hormone on liver growth and DNA polymerase activity.

Abstract

The administration of glucocorticoid hormone to rapidly growing weanling rats results in a virtually complete inhibition of liver DNA synthesis. It is shown that upon cessation of treatment not only is there a prompt resumption of liver DNA synthesis, but that synthesis actually proceeds at a rate greatly exceeding that in control animals. The burst of new DNA synthesis which follows the release of the cortisone-induced inhibition represents an approximate doubling of the normal rate of synthesis and continues until the DNA content of the livers of the steroid-treated animals reaches that of the untreated controls. The demonstration that cessation of steroid treatment is followed not only by a period of rapid body weight gain but by a genuine acceleration of hyperplasia as well substantiates the earlier but hitherto unproven concept of post-steroid “catch-up” growth. A detailed comparison of the sequence of changes in liver DNA synthesis with that of changes in liver DNA polymerase activity makes it unlik...