Effect of Preeclampsia on Ultrastructure of Thyroid Gland, Hepatic Type 1 Iodothyronine Deiodinase, and Thyroid Hormone Levels in Rats

Abstract

Background. Although hypothyroidism during pregnancy may develop grave outcomes for both mothers and offspring, management of which is still a challenge due to the insufficient understanding of this disease. The close correlation between hypothyroidism and preeclampsia is well documented, suggesting that preeclampsia is a potential risk factor for the development of maternal hypothyroidism. However, the exact role of preeclampsia in gestational hypothyroidism is still obscure. Objective. In this study, we explored the possible mechanisms of the effect of preeclampsia on thyroid function of maternal rats. Methods. Thirty pregnant rats were randomly divided into normal pregnancy control (NOP), preeclampsia (PE), and preeclampsia supplemented with amlodipine besylate (PEAml). NG-Nitro-L-arginine-methyl ester was used to induce preeclamptic symptoms. On gestational day 21, rats were sacrificed, and then, the ultrastructure of the thyroid gland, type 1 iodothyronine deiodinase (Dio1) expression, and serum-free thyroxine (FT4), free triiodothyronine (FT3), and thyroid stimulation hormones (TSH) were assessed. Results. Compared to NOP rats, results of PE rats showed that thyroid follicular cells’ ultrastructure was damaged; both hepatic Dio1 mRNA and protein levels were decreased. Interestingly, these changes were ameliorated in PEAml rats. Additionally, FT4, FT3, and TSH levels have no significant differences among groups. Conclusion. These findings indicated that preeclampsia could disrupt synthesis, secretion, and metabolism function of thyroid hormones by damaging thyroid follicular cells and interfering Dio1 expression.

Association of Gestational Free and Total Triiodothyronine With Gestational Hypertension, Preeclampsia, Preterm Birth, and Birth Weight: An Individual Participant Data Meta-analysis

“…A counterargument for this is that there was no association of TSH or FT4 with gestational hypertension in our previous study, which is opposite to the current study. Future studies are required to investigate any potential disruption of thyroid function during preeclampsia following experimental studies that show disruption of transthyretin physiology and hepatic deiodinase activity ( 23 , 24 ). This may indicate that current results and previous findings on FT4 and TSH could be spurious due to reverse causation.…”