Hypothyroxinemia Induced by Mild Iodine Deficiency Deregulates Thyroid

Hypothyroxinemia Induced by Mild Iodine Deficiency Deregulates Thyroid Proteins during Gestation and Lactation in Dams By Wei, Yi Wang, Jing Dong, Yaun Wang, Hui Min, Binbin Song, Zhongyan Shan, Weiping Teng, Qi Xi, and Jie Chen Melissa Zargham

Purpose • The object of the study was to explore the effect of mild iodine deficiencyinduced maternal hypothyroxinemia during pregnancy and lactation on thyroidal proteins. • Importance: Maternal iodine deficiency during pregnancy and lactation results in decreased IQ in children.

Introduction • Iodine = essential trace element for the thyroid • Produces triiodothyronine (T 3) and thyroxine (T 4) • • Hypothyrodism • Iodine deficiency (ID) can lead to Hypothyroxinemia • Mild ID is recognized as the most common reason causing hypothyroxinemia

Introduction • Thyroid and Thyroid function: • • Thyroid transcription factor 1 (TTF 1) Paired box gene 8 (PAX 8) • Thyroid hormone • • Type 1 iodothyronine deiodinase (DIO 1) Type 2 iodothyronine deiodinase (DIO 2)

Background • Thyroid Hormone Synthesis • • Iodide (I-) actively taken up into the thyroid cells • MIT is iodinated in the 5 th position forming Thg. DIT • • Iodide is oxidized to iodine and bound to the tyrosyl residues of thyroglobulin forming thyroglobulin-3 -monoiodotyrosine (Thg-MIT) Two DITs couple to form Thg-T 4. DIT also couples with MIT to form T 3 Thg-T 4 and Thg-T 3 are hydrolyzed by lysosomal proteases and T 4 and T 3 are released into blood

Hypothesis • Mild ID diet may induce mild ID by impacting the expressions of thyroidal TTF 1, PAX 8, and NIS. In gestational and lactational dams, mild ID may induce hypothyroxinemia and disturb thyroidal DIO 1 and DIO 2 expressions.

Methods • • Female Wistar rats Three groups: • • • Control group ( iodine intake of 7. 0 μg/day) Mild ID group (iodine intake of 3. 0 μg/day) Severe ID group (iodine intake of 1. 5 μg/day) Blood was obtained and tested via a supersensitive chemiluminescence immunoassay Mated with normal male rats

Methods • • Measurement of Thyroid Iodine Content: • Thyroid glands were collected from 5 dams on gestational day (GD)19 and postpartum day (PN) 21 • Measured by ammonium persulfate-arsenic cerium catalytic spectrophotometry Western Blotting • • • Rats were euthanized Thyroid gland tissue was collected Chemiluminescence

Results • Thyroid Iodine Content: Thyroid gland weight significantly increased in mild and severe ID • Western Blotting:

Western Blotting Results

Results DIO 1 DIO 2

Discussion/Conclusion • • Major findings: • Increased thyroid weights, decreased thyroid iodine contents and up-regulation of thyroidal TTF 1, PAX 8, NIS, DIO 1 and DIO 2 Hypothyroidism induced by severed ID not common but hypothyroxinemia still prevalent Maternal hypothyroxinemia may lead to irreversible CNS damage in humans. Results showed that, in the gestational and lactational dams, the maternal mild ID diet could cause mild ID by impacting thyroidal TTF 1, PAX 8, and NIS. Also, hypothyroxinemia induced by mild ID increased the levels of DIO 1 and DIO 2.

Resources • Western Blotting Image http: //www. piercenet. com/guide/fast-westernblotting-product-selection-guide • Wei, W. , Wang, Y. , Dong, J. , Wang, Y. , Min, H. , Song, B. , . . . Chen, J. (2013). Hypothyroxinemia induced by mild iodine deficiency deregulats thyroid proteins during gestation and lactation in dams. International Journal of Environmental Research and Public Health, 10(8), 3233 -45. Retrieved from http: //search. proquest. com/docview/1468936671? accountid=13645 • Gropper, S & Smith, J. Essential Trace and Ultratrace Minerals. Advanced Nutrition and Human Metabolism (6 th ed. ). (pp. 531 -533). Belmont: Wadsworth Cengage Learning.