Selenium and iodine deficiencies: effects on brain and brown adipose tissue selenoenzyme activity and expression

J H Mitchell, Fergus Nicol, G J Beckett, John Arthur

Research output: Contribution to journalArticle

44 Citations (Scopus)

Abstract

Adequate dietary iodine supplies and thyroid hormones are needed for the development of the central nervous system (CNS) and brown adipose tissue (BAT) function. Decreases in plasma thyroxine (T-4) concentrations may increase the requirement for the selenoenzymes types I and II iodothyronine deiodinase (ID-I and ID-II) in the brain and ID-II in BAT to protect against any fall in intracellular 3,3',5 tri-iodothyronine (T-3) concentrations in these organs. We have therefore investigated selenoenzyme activity and expression and some developmental markers in brain and BAT of second generation selenium- and iodine-deficient rats. Despite substantial alterations in plasma thyroid hormone concentrations and thyroidal and hepatic selenoprotein expression in selenium and iodine deficiencies, ID-I, cytosolic glutathione peroxidase (cGSHPx) and phospholipid hydroperoxide glutathione peroxidase (phGSHPx) activities and expression remained relatively constant in most brain regions studied. Additionally, brain and pituitary ID-II activities were increased in iodine deficiency regardless of selenium status. This can help maintain tissue Tg concentrations in hypothyroidism. Consistent with this, no significant effects of iodine or selenium deficiency on the development of the brain were observed, as assessed by the activities of marker enzymes. In contrast, BAT from selenium- and iodine-deficient rats had impaired thyroid hormone metabolism and less uncoupling protein than in tissue from selenium-and iodine-supplemented animals. Thus, the effects of selenium and iodine deficiency on the brain are limited due to the activation of the compensatory mechanisms but these mechanisms are less effective in BAT.

Original languageEnglish
Pages (from-to)255-263
Number of pages9
JournalJournal of Endocrinology
Volume155
Issue number2
Publication statusPublished - Nov 1997

Keywords

  • II IODOTHYRONINE DEIODINASE
  • HYDROPEROXIDE GLUTATHIONE-PEROXIDASE
  • THYROID-HORMONE ECONOMY
  • DEVELOPING RAT-BRAIN
  • PROTEIN GENE
  • HYPOTHYROIDISM
  • SELENOCYSTEINE
  • SELENOPROTEIN
  • LIVER
  • TRIIODOTHYRONINE

Cite this

Selenium and iodine deficiencies: effects on brain and brown adipose tissue selenoenzyme activity and expression. / Mitchell, J H ; Nicol, Fergus; Beckett, G J ; Arthur, John.

In: Journal of Endocrinology, Vol. 155, No. 2, 11.1997, p. 255-263.

Research output: Contribution to journalArticle

Mitchell, J H ; Nicol, Fergus ; Beckett, G J ; Arthur, John. / Selenium and iodine deficiencies: effects on brain and brown adipose tissue selenoenzyme activity and expression. In: Journal of Endocrinology. 1997 ; Vol. 155, No. 2. pp. 255-263.
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