Hazards of Bisphenol A on the Thyroid Gland of Adult Male Albino Rats and Possibility of Recovery after its Withdrawal

Abstract
Background: Bisphenol A (BPA) is a chemical pollutant and one of the endocrinal disrupting factors.
Aim of Study: This study was designed to evaluate the possible changes that may occur in thyroid gland of male adult rats following BPA administration and to access the possibility of the thyroid recovery after stoppage of its admin-istration.
Materials and Methods: 36 male adult wistar albino rats were divided into 3 equal groups (control, BPA treated and recovery). For 8 weeks, each animal in the treated group received orally BPA 50mg/kg/day, also rats in the recovery group dosed BPA similar to the treated group then held for another 4 weeks without BPA administration. Finally when the experiment was ended, the rats were anesthetized, sacrificed and blood samples were obtained to measure the levels of thyroid hormones. The thyroid gland was processed for his-tological, histochemical and immunohistochemical Bcl2 studies. Also, morphometric studies were accessed.
Results: In BPA treated group, there were vacuolated follicular cells, exfoliation of epithelial cells inside the colloid and congested capillaries in the interfollicular spaces. Marked decrease of colloidal PAS reaction and the Bcl2 immunoreac-tion with increase of the amount of collagen fibers were observed. Also, these results were demonstrated morphomet-rically. Significant reduction of triiodo-thyronine (T3), thy-roxine (T4) and significant increase of thyroid stimulating hormone (TSH) were recorded. In the recovery group, partial improvement of the histological, histochemical, biochemical and immunohistochemical changes caused by BPA was re-corded.
Conclusion: Exposure to BPA could result in histological and functional changes of thyroid gland that were incompletely improved after stoppage of BPA administration.