Features of Structural and Functional Organization of the Thyroid Gland in Rats with Microelementosis

This research highlights the study of the influence of combined deficiencies of iodine and copper, selenium or iron on structural and functional features of the thyroid gland (TG). Rats of both groups were kept on iodine-deficient diet for 45 days and received mercazolilum with drinking water until the 15th day of the experiment. Copper deficiency was induced by daily addition of d-penicillamine to drinking water (cuprenil, 100mg/100g body weight, for 21 days). Selenium deficiency was induced by addition of balanced selenium-deficient diet to the basic diet for 45 days. Iron deficiency was induced by daily intraperitoneal administration of iron chelator deferoxamine (desferal, 20mg/100g body weight, for 15 days). Hypofunction of TG secondary to iodine deficiency was found to cause the reduction in thyroid hormones synthesis in comparison with the control group. The follicles of TG were multifarious, often deformed, overstretched by the colloid, the surface area of which was twice (p<0.01) larger than analogous indices in animals of the control group. Hypofunction of TG on the background of combined microelement imbalance caused more expressed violations. So, the elevated serum TSH level by 77.8-88.9% (р<0.05) and index fТ3/fТ4by 65.0-90.0% (р<0.05) were detected in rats with combined deficiency of microelements indicating the decrease in functional ability of TG. Copper, selenium and iron deficiencies were followed by significant increase in the follicular surface area (by 15.7-26.9 %) on the background of the decrease in the height (by 54.6-55.05%) and the surface area of the follicular epithelium (by 33.4-48.6 %), increase in the colloidal density (by 8.2-13.8 %) and index of its accumulation (by 1.8-2.5 times) in comparison with those in animals with isolated iodine deficiency. Thus, combined deficiency of microelements causes more severe structural and functional changes of TG than isolated iodine deficiency.