Effects of combined iodine and selenium deficiency on thyroid hormone metabolism in rats

Abstract

This paper compares the effects of combined iodine and selenium deficiency, of single deficiencies of these trace elements, and of no deficiency on thyroid hormone metabolism in rats. In rats deficient in both trace elements, thyroidal triiodothyronine (T3), thyroidal thyroxin (T4), thyroidal total iodine, hepatic T4, and plasma T4 were significantly lower, and plasma thyroid-stimulating hormone (TSH) and thyroid weight were significantly higher than in rats deficient in iodine alone. Plasma and hepatic T3 concentrations were similar in the dietary groups. Hepatic type I iodothyronine deiodinase (ID-I) activity was inhibited by selenium deficiency irrespective of the iodine status. Type II deiodinase (ID-II) activity in the brain was significantly higher and in pituitary, significantly lower in combined deficiency than in iodine deficiency alone. These data show that selenium can play an important role in determining the severity of the hypothyroidism associated with iodine deficiency.

Effects of selenium and iodine supplementation on the growth rate, mohair production, and thyroid status of Angora goat kids

“…Supplementation with Se decreased plasma total thyroxine concentration, presumably reflecting increased peripheral metabolism of thyroxine by 5-deiodinase (Beckett et al 1993). The additive nature of the effects of treatment with Se and I on plasma thyroxine supports the findings for calves (Wichtel et al 1995).…”

“…The activity of the seleno-enzyme type I triiodothyronine 5 -deiodinase is sensitive to changes in Se intake (Beckett et al 1993). Supplementary Se causes plasma concentrations of triiodothyronine to be increased and thyroxine to be decreased in calves (Wichtel et al 1995) and ewes (Donald et al 1993) grazing pasture deficient in Se.…”

“…Deficiency of Se can exacerbate the hypothyroidism associated with deficiency of iodine (I) in rats (Beckett et al 1993). Interactions between intakes of Se and I that affect animal performance would have important implications for livestock grazing forages with low concentrations of both of these trace elements.…”

Ciprofloxacin induced hormonal changes in the thyroid gland of rats and Anti-oxidant vitamin A, C and E as rescue agents

“…The drug had increased the T 3 and T 4 levels in long duration of its treatment with no change in TSH titres. Tricyclic anti depressants (TCAs) interface with the hypothalamic -pituitary -thyroid (HPT) axis via the serotonergic and nor adenergic systems, this lead to a decrease in TSH (Beckett et al, 1993).. The same study also observed that, by long term administration of clomipramine decrease T 4 , fT 4 (free T 4 ) and rT 3 (reverse T 3 ).…”

Production of Selenium-Enriched Yeast (Kluyveromyces marxianus) Biomass in a whey-based Culture Medium

“…Many enzymes require selenium as a cofactor, being one of particular interest the glutathione peroxidase, which catalyzes lipid hydroperoxides to hydroxy acids and water (Smith et al, 1974). Moreover, selenium is crucial for the correct function of the thyroid gland (Beckett et al, 1993). Cows with selenium deficiency are associated with immunological alteration, increasing placental retention and decreased milk production (Julien et al, 1976;Moeini et al, 2009).…”