Nagasaka A, Yoshida S, Nakai A, Ohyama T, Iwase K, Ohtani S, Nakagawa H, Masunaga R, Kato S, Kawabe T
Department of Internal Medicine, Fujita-Gakuen Health University School of Medicine, Aichi, Japan.
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.
利用垂体切除的大鼠，已表明肾上腺和睾丸中的DNA聚合酶β活性在很大程度上受垂体促激素的影响。甲状腺提取物的蔗糖梯度离心显示DNA聚合酶β活性有三个峰，沉降系数分别为3.3S、7.3S和12S。其中，垂体切除导致3.3S DNA聚合酶β减少，而其他分子形式仅受到轻微影响。DNA聚合酶α和γ活性不受垂体切除的影响。垂体切除引起的DNA聚合酶β的这些变化可通过每天腹腔注射促甲状腺激素（TSH）而逆转。此外，通过给予1-甲基-2-巯基咪唑诱导的过量TSH刺激甲状腺，导致甲状腺所有形式的DNA聚合酶β增加。这些结果表明，垂体切除后DNA聚合酶水平相对恒定，但大鼠甲状腺中的DNA聚合酶β也主要通过沉降系数为3.3S的聚合酶β活性变化而受到TSH的调节。
