The distribution patterns of trace elements in the brain and erythrocytes in a rat experimental model of iodine deficiency

Cretinism is a disease characterized by neurological defects associated with severe iodine deficiency. In a rat model of severe iodine deficiency, we investigated the distribution pattern of trace elements (iodine I], selenium Se], and bromine Br] in brain tissue samples; potassium K], calcium Ca], manganese Mn], iron Fe], copper Cu], zinc Zn], rubidium Rb], and lead Pb] in erythrocytes) after supplementing the rats with I and/or Se. Neutron activation analysis, proton induced x-ray emission and x-ray fluorescence were used. The serum levels of total and free thyroxine (T4, FT4), and of total, free, and reverse triiodothyronine (T3, FT3, rT3, respectively) were assessed by radioimmunoassay. The results were statistically evaluated by one-way analysis of variance and bivariate correlation. The study indicated that the levels of T4, FT4, and rT3 increased in the serum of iodine-deficient rats supplemented with I or I + Se. In the same animals, we documented alterations of the content of Br in the brain, and of Zn, Mn, Cu, and Rb in erythrocytes, whereas the brain content of I and Se was unchanged. Thus, I and I + Se supplementation improves thyroid hormone metabolism but affects the content of selected trace elements in erythrocytes and of Br in the brain. The data stimulate further clarification of the role of trace elements in the central nervous system.