Hormonal regulation of DNA polymerase-beta activity in the rat thyroid gland

J Endocrinol. 1988 Nov;119(2):303-8. doi: 10.1677/joe.0.1190303.


Using hypophysectomized rats, it has been shown that DNA polymerase-beta activity in the adrenal gland and testis is largely influenced by pituitary trophic hormones. Sucrose gradient centrifugation of thyroid extracts revealed three peaks of DNA polymerase-beta activity sedimenting at 3.3S, 7.3S and 12S. Of these, hypophysectomy induced a decrease in the 3.3S DNA polymerase-beta, whereas other molecular forms were affected only slightly. DNA polymerase-alpha and -gamma activities were unaffected by hypophysectomy. These changes in DNA polymerase-beta caused by hypophysectomy were reversed by daily i.p. injection of TSH. Furthermore, stimulation of the thyroid by excess TSH induced by the administration of 1-methyl-2-mercaptoimidazole resulted in an increase of all forms of thyroid DNA polymerase-beta. These results show that the level of DNA polymerase is relatively constant after hypophysectomy but that DNA polymerase-beta in the rat thyroid gland is also modulated by TSH mainly through the change of activity of the polymerase-beta which sediments at 3.3S.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • DNA Polymerase I / metabolism*
  • DNA Polymerase II / metabolism
  • DNA Polymerase III / metabolism
  • Hypophysectomy
  • Male
  • Methimazole / pharmacology
  • Rats
  • Rats, Inbred Strains
  • Thyroid Gland / enzymology*
  • Thyrotropin / pharmacology*


  • Methimazole
  • Thyrotropin
  • DNA Polymerase I
  • DNA Polymerase II
  • DNA Polymerase III