title: Effects of selenium and iodine deficiency on iodothyronine deiodinases in brain, thyroid and peripheral tissue.
abstract: Long term nutritional selenium (Se) deficiency had only marginal effects on the thyroid T4 and T3 content and on the activity of the selenoenzyme type I deiodinase (5'D-I) in the thyroid gland. These findings reveal a remarkable resistance of the thyroid to Se-deficiency which may substantially contribute to the observed maintenance of T4 and T3 levels in circulating blood. In contrast to its maintained thyroidal activity, 5'D-I in peripheral tissues like liver and kidney was strongly decreased by Se-deficiency. The observed decrease of type II deiodinase (5'D-II) in the cerebral cortex of Se-deficient rats was obviously caused by the suppressing regulatory effect of elevated cortex T4 concentrations. The severalfold 5'D-II enhancement in iodine depleted animals was not abolished by additional Se-deficiency, suggesting that brain type II deiodinase is not a selenoenzyme. The role of selenium for cortex type III 5-deiodinase, which was moderately decreased in selenium as well as iodine-deficient rats, awaits definite evaluation by further studies. The different responsiveness to thyroidal and hepatic 5'D-I to Se restriction is further evidence for priorities in the selenium supply to different tissues.
authors.affiliation: Department of Nuclear Medicine, Klinikum Steglitz, Free University Berlin, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Meinhold
authors.forename: A
authors.initials: A
authors.lastname: Campos-Barros
authors.forename: D
authors.initials: D
authors.lastname: Behne
mesh_terms: D000818:Animals; D001921:Brain / Q000201:enzymology*; D005260:Female; D007453:Iodide Peroxidase / Q000502:physiology*; D007455:Iodine / Q000172:deficiency* / Q000502:physiology; D007527:Isoenzymes / Q000502:physiology*; D007668:Kidney / Q000201:enzymology; D008099:Liver / Q000201:enzymology; D051381:Rats; D012643:Selenium / Q000502:physiology*; D013961:Thyroid Gland / Q000201:enzymology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
chemical_list: D007527:Isoenzymes; D014284:Triiodothyronine; D007455:Iodine; D007453:Iodide Peroxidase; D012643:Selenium; D013974:Thyroxine