Hypothyroxinemia induced by mild iodine deficiency deregulats thyroid proteins during gestation and lactation in dams

Abstract

The main object of the present study was to explore the effect on thyroidal proteins following mild iodine deficiency (ID)-induced maternal hypothyroxinemia during pregnancy and lactation. In the present study, we established a maternal hypothyroxinemia model in female Wistar rats by using a mild ID diet. Maternal thyroid iodine content and thyroid weight were measured. Expressions of thyroid-associated proteins were analyzed. The results showed that the mild ID diet increased thyroid weight, decreased thyroid iodine content and increased expressions of thyroid transcription factor 1, paired box gene 8 and Na+/I- symporter on gestational day (GD) 19 and postpartum days (PN) 21 in the maternal thyroid. Moreover, the up-regulated expressions of type 1 iodothyronine deiodinase (DIO1) and type 2 iodothyronine deiodinase (DIO2) were detected in the mild ID group on GD19 and PN21. Taken together, our data indicates that during pregnancy and lactation, a maternal mild ID could induce hypothyroxinemia and increase the thyroidal DIO1 and DIO2 levels.

Figure 1

The increased thyroid weight in the thyroid in all groups on GD19 and PN21 (n = 5). * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05.

Figure 2

The decreased thyroid iodine content in the thyroid in all groups on GD19 and PN21 (n = 5). * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05.

Figure 3

Up-regulated protein levels of TTF1 in the thyroid. The upper bands (A) depict representative findings for rats subjected to mild ID and severe ID, respectively. The lower bar graphs show the results of the semi-quantitative measurement of TTF1 (B) following mild ID and severe ID treatment. The height of each bar represents the mean ±SD for the groups. At each time point, * compared to the control, p< 0.05; # compared to the mild ID, p < 0.05 (n=5).

Figure 4

Up-regulatedprotein levels of PAX8 in the thyroid. The upper bands (A) depict representative findings for rats subjected to mild ID and severe ID. The lower bar graphs show the results of the semi-quantitative measurement of PAX8 (B) following mild ID and severe ID treatment. The height of each bar represents the mean ±SD for the groups. At each time point, * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05 (n=5).

Figure 5

Up-regulated protein levels of NIS in the thyroid. The upper bands (A) depict representative findings for rats subjected to mild ID and severe ID. The lower bar graphs show the results of the semi-quantitative measurement of NIS (B) following mild ID and severe ID treatment. The height of each bar represents the mean ±SD for the groups. At each time point, * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05 (n=5).

Figure 6

Up-regulated protein levels of DIO1 in the thyroid. The upper bands (A) depict representative findings for rats subjected to mild ID and severe ID. The lower bar graphs show the results of the semi-quantitative measurement of DIO1 (B) following mild ID and severe ID treatment. The height of each bar represents the mean ±SD for the groups. At each time point, * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05 (n=5).

Figure 7

Up-regulated protein levels of DIO2 in the thyroid. The upper bands (A) depict representative findings for rats subjected to mild ID and severe ID. The lower bar graphs show the results of the semi-quantitative measurement of DIO2 (B) following mild ID and severe ID treatment. The height of each bar represents the mean ±SD for the groups. At each time point, * compared to the control, p < 0.05; # compared to the mild ID, p < 0.05 (n=5).