Glucocorticoid mediated changes in DNA synthesis and DNA polymerase activities were superimposed on the age-dependent changes in DNA synthesis and DNA polymerase activities in the pancreas of actively growing female rats. DNA synthesis was measured by estimating the amount of radioactive thymidine incorporated into DNA in vivo. The DNA polymerase was assayed by determining the amount of [3H]TTP polymerized in vitro into the acid insoluble fraction in the presence of activated calf thymus DNA. The age-dependent increase in the DNA content and subsequent cessation of the increase are intimately related to the synthesis of DNA, and the changes in the DNA synthesis accompany corresponding changes in the tissue level of DNA polymerase activities. Glucocorticoid has a biphasic effect on DNA synthesis, first an initial inhibition of synthesis then a stimulation of synthesis. The inhibition and stimulation of DNA synthesis mediated by the steroid are attended by concomitant decrease and increase, respectively, of the tissue levels of the polymerase activities.
ASJC Scopus subject areas
- Pathology and Forensic Medicine
- Molecular Biology
- Clinical Biochemistry