Orally Administered Bisphenol A Impairs Normal Thyroid Functions Altering Thyroid Hormones Homeostasis in Female Wistar Rats

ABSTRACT
Background Objective: Bisphenol A (BPA) is an endocrine-disrupting chemical used on a wide range in the industry. Several studies reported that BPA may cause cardiovascular disorders in humans and animals. The present study aims to investigate the effect of BPA on the thyroid gland of female rats. Materials and Methods: The rats received a daily oral administration of BPA (0.05 – 1.0 mg kg^-1 for 13 weeks). Thyroid Stimulating Hormone (TSH), Thyroxine (T₄) and Triiodothyronine (T₃) were assayed using an Auto chemical analyzer and data obtained were subjected to statistical analysis with the Statistical Package for the Social Sciences (SPSS) software. Results: It was found that BPA at the eleven studied doses induced a significant increase in the Thyroxin Stimulating Hormone (TSH), Free Thyroxin (FT₄), Total Thyroxin (TT₄) level, while the bound thyroxin is low compared to the control. The Free Triiodothyronine (FT₃) and Total Triiodothyronine (TT₃) were initially low at group 1 but at the other doses, they were on the increase. The bound triiodothyronine is lower when compared to that of the control throughout the studied time intervals. Conclusion: These results suggest that BPA has thyroid toxic effects which are mediated by the oxidative stress resulting from the overproduction of free radicals, BPA may also participate in the thyroid gland function disturbances.