Horm Metab Res 2015; 47(12): 910-915
DOI: 10.1055/s-0035-1550008
Endocrine Research
© Georg Thieme Verlag KG Stuttgart · New York

MCT8 is Downregulated by Short Time Iodine Overload in the Thyroid Gland of Rats

E. C. L. de Souza*
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
G. R. M. Dias*
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
R. C. Cardoso
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
L. P. Lima
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
2   Departamento de Ciências Básicas, Pólo de Nova Friburgo, UFF, Brazil
,
R. S. Fortunato
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
T. J. Visser
3   Department of Internal Medicine, Erasmus University Medical Center, Rotterdam, The Netherlands
,
M. Vaisman
4   Universitary Hospital Clementino Fraga Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
A. C. F. Ferreira
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
5   Polo de Xerém/NUMPEX, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
,
D. P. Carvalho
1   Laboratory of Endocrine Physiology Doris Rosenthal, Institute of Biophysics Carlos Chagas Filho, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil
› Author Affiliations
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Publication History

received 07 January 2015

accepted 28 April 2015

Publication Date:
28 May 2015 (online)

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Abstract

Wolff-Chaikoff effect is characterized by the blockade of thyroid hormone synthesis and secretion due to iodine overload. However, the regulation of monocarboxylate transporter 8 during Wolff-Chaikoff effect and its possible role in the rapid reduction of T4 secretion by the thyroid gland remains unclear. Patients with monocarboxylate transporter 8 gene loss-of-function mutations and monocarboxylate transporter 8 knockout mice were shown to have decreased serum T4 levels, indicating that monocarboxylate transporter 8 could be involved in the secretion of thyroid hormones from the thyroid gland. Herein, we aimed to evaluate the regulation of monocarboxylate transporter 8 during the Wolff-Chaikoff effect and the escape from iodine overload, besides the importance of iodine organification for this regulation. Monocarboxylate transporter 8 mRNA and protein levels significantly decreased after 1 day of NaI administration to rats, together with decreased serum T4; while no alteration was observed in LAT2 expression. Moreover, both monocarboxylate transporter 8 expression and serum T4 was restored after 6 days of NaI. The inhibition of thyroperoxidase activity by methimazole prevented the inhibitory effect of NaI on thyroid monocarboxylate transporter 8 expression, suggesting that an active thyroperoxidase is necessary for MCT8 downregulation by iodine overload, similarly to other thyroid markers, such as sodium iodide symporter. Therefore, we conclude that thyroid monocarboxylate transporter 8 expression is downregulated during iodine overload and that the normalization of its expression parallels the escape phenomenon. These data suggest a possible role for monocarboxylate transporter 8 in the changes of thyroid hormones secretion during the Wolff-Chaikoff effect and escape.

*  These authors contributed equally to this work.


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