Background: The worldwide used bisphenol A (BPA) which is incorporated in many plastic industries is considered as an endocrine disruptor. Warnings raised by many agencies against the excessive use of such substances because of its confirmed hazardous effects. Selenium (Se) is known to have antioxidant role in living systems.
Aim of the work: The aim of the current study was to evaluate the extent to which BPA can affect the thyroid gland structure and function and if there is any protective role for selenium.  Material and Methods: Twenty four adult male rats divided equally into three groups. Group I as a control, group II included rats that received 50 mg/kg/ day bisphenol orally for eight weeks and group III that received bisphenol in the same dose for the same duration concomitantly with selenium in a dose of 0.5 mg/kg. At the end of the experiment, blood samples were taken for hormonal essay and statistical analysis. Thyroid gland tissue samples were processed for histological and immunohistochemical study.
Results: BPA-treated rats showed degenerative changes in the form of decreased or absent colloid and fusion of the follicles. Other follicles showed signs of hyperactivity as microfollicles, follicular epithelial cell stratification and many lysosomes. Strong positive inducible nitric oxide synthase immunoreactivity and highly significant increase of serum TSH with decreased T3 and T4 were recorded. BPA+selenium treated group revealed nearly normal appearance of thyroid gland architecture.  Conclusion: BPA had deleterious effects on thyroid structure and function. Concomitant administration of selenium preserved to a great extent the thyroid gland architecture.