| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
ARTICLES |
Departments of Physiology and Medicine, Dartmouth Medical School, Lebanon, New Hampshire 03756-0001; and Reactor Research Laboratories, University of Missouri, Columbia, Missouri 65211
Address all correspondence and requests for reprints to: Valerie Anne Galton, Department of Physiology, Dartmouth Medical School, 1 Medical Center Drive, Borwell Building, Lebanon, New Hampshire 03756-0001. E-mail: val.galton{at}dartmouth.edu
The iodothyronine deiodinases, D1, D2, and D3, all contain selenium (Se) in the form of selenocysteine at their active sites, and they play crucial roles in determining the circulating and intracellular levels of the active thyroid hormone (TH), T3. However, not only are serum T3 levels normal in Se-deficient rats but phenotypic and reproductive abnormalities are minimal, and it has been suggested that regulatory mechanisms exist to conserve Se in critical tissues.
The present study was designed to determine, in rats: 1) whether the effects of Se-deficiency are greater in the fetus and neonate than in the adult; 2) whether there are tissues other than brain and thyroid in which deiodinase activities are maintained; 3) whether the maintenance of deiodinase activity in a specific tissue is associated with a concomitant preservation of Se level in that tissue; and 4) whether TH economy and general health is maintained over several generations. The tissues studied included liver, cerebrum, thyroid, pituitary, skin, brown adipose tissue, uterus, ovary, testis, placenta, and the implantation site (uterus plus contents) at E9.
The results have revealed that, with the exception of liver, skin, and nonpregnant uterus, all of the tissues studied maintained substantial deiodinase activity (>50%) during prolonged Se-deficiency. Second, although the ability of a tissue to maintain deiodinase activity in the face of dietary Se deprivation was associated in some tissues with a concomitant local preservation of Se concentration, this was not the case for all tissues. Only when Se levels were decreased by more than 80% was deiodinase activity markedly decreased. Third, the effects of Se-deficiency were no greater in the fetus than in the adult; and fourth, at the level of Se-deficiency employed in this study, TH economy and general health were successfully maintained over six generations of Se-deficient rats. How Se levels are maintained in specific tissues, whether Se is sequestered in specific cells of a tissue or organ during dietary Se deprivation, and the precise mechanisms by which plasma T3 levels are maintained in Se-deficient animals remain unanswered. Further insights may be gained by using diets that are even lower in Se than those that were used herein and/or by conducting studies using radioactive forms of Se and thyroid hormones.
This article has been cited by other articles:
![]() |
G. F Combs Jr, D. N Midthune, K. Y Patterson, W. K Canfield, A D. Hill, O. A Levander, P. R Taylor, J. E Moler, and B. H Patterson Effects of selenomethionine supplementation on selenium status and thyroid hormone concentrations in healthy adults Am. J. Clinical Nutrition, June 1, 2009; 89(6): 1808 - 1814. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. P Rayman, A. J Thompson, B. Bekaert, J. Catterick, R. Galassini, E. Hall, M. Warren-Perry, and G. J Beckett Randomized controlled trial of the effect of selenium supplementation on thyroid function in the elderly in the United Kingdom Am. J. Clinical Nutrition, February 1, 2008; 87(2): 370 - 378. [Abstract] [Full Text] [PDF] |
||||
![]() |
L. Schomburg, C. Riese, M. Michaelis, E. Griebert, M. O. Klein, R. Sapin, U. Schweizer, and J. Kohrle Synthesis and Metabolism of Thyroid Hormones Is Preferentially Maintained in Selenium-Deficient Transgenic Mice Endocrinology, March 1, 2006; 147(3): 1306 - 1313. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Kohrle, F. Jakob, B. Contempre, and J. E. Dumont Selenium, the Thyroid, and the Endocrine System Endocr. Rev., December 1, 2005; 26(7): 944 - 984. [Abstract] [Full Text] [PDF] |
||||
![]() |
R. A. Sunde, J. K. Evenson, K. M. Thompson, and S. W. Sachdev Dietary Selenium Requirements Based on Glutathione Peroxidase-1 Activity and mRNA Levels and Other Se-Dependent Parameters Are Not Increased by Pregnancy and Lactation in Rats J. Nutr., September 1, 2005; 135(9): 2144 - 2150. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. J Beckett and J. R Arthur Selenium and endocrine systems J. Endocrinol., March 1, 2005; 184(3): 455 - 465. [Abstract] [Full Text] [PDF] |
||||
![]() |
E. C. Wasco, E. Martinez, K. S. Grant, E. A. St. Germain, D. L. St. Germain, and V. A. Galton Determinants of Iodothyronine Deiodinase Activities in Rodent Uterus Endocrinology, October 1, 2003; 144(10): 4253 - 4261. [Abstract] [Full Text] [PDF] |
||||
![]() |
G. G. J. M. Kuiper, W. Klootwijk, and T. J. Visser Substitution of Cysteine for Selenocysteine in the Catalytic Center of Type III Iodothyronine Deiodinase Reduces Catalytic Efficiency and Alters Substrate Preference Endocrinology, June 1, 2003; 144(6): 2505 - 2513. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. Friedrichsen, S. Christ, H. Heuer, M. K. H. Schafer, A. Mansouri, K. Bauer, and T. J. Visser Regulation of Iodothyronine Deiodinases in the Pax8-/- Mouse Model of Congenital Hypothyroidism Endocrinology, March 1, 2003; 144(3): 777 - 784. [Abstract] [Full Text] [PDF] |
||||
![]() |
A. C. Bianco, D. Salvatore, B. Gereben, M. J. Berry, and P. R. Larsen Biochemistry, Cellular and Molecular Biology, and Physiological Roles of the Iodothyronine Selenodeiodinases Endocr. Rev., February 1, 2002; 23(1): 38 - 89. [Abstract] [Full Text] [PDF] |
||||
![]() |
W. W. Li, C. Le Goascogne, M. Ramauge, M. Schumacher, M. Pierre, and F. Courtin Induction of Type 3 Iodothyronine Deiodinase by Nerve Injury in the Rat Peripheral Nervous System Endocrinology, December 1, 2001; 142(12): 5190 - 5197. [Abstract] [Full Text] [PDF] |
||||
![]() |
J.-P. Chanoine, J. Nève, S. Wu, J. Vanderpas, and P. Bourdoux Selenium Decreases Thyroglobulin Concentrations But Does Not Affect the Increased Thyroxine-to-Triiodothyronine Ratio in Children with Congenital Hypothyroidism J. Clin. Endocrinol. Metab., March 1, 2001; 86(3): 1160 - 1163. [Abstract] [Full Text] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |