[Rat thyrocytes under oxidative stress]

Iodine is the most important regulator of the functional activity of thyroid cells; however, not only may iodine deficiency be responsible for impaired metabolic processes in the thyrocytes. The purpose of the study was to examine the impact of Fe2+/ascorbate-dependent activation ofoxidative stress on the functional activity of cultured rat thyrocytes. The 2.88-6.76-fold rise (p < 0.001) in the concen-tration of aldehyde lipid peroxidation products was shown to be followed by the decreased thyrocytic generation ofthyroxine (Т4) the latter being most pronounced 6 hours late (by 1.7-3.2 times), by a 120-250% increase in triiodothyronine (Т3) excretion and a 1.5-3.0-fold rise in Т3/T4 ratios in the culture medium. This is most likely to result from impaired thyrocytic iodine organisation under activated oxidative stress. The findings suggest that the most important stages of biosynthesis of thyroid hormones in the thyroid are significantly sensitive to the elevated concentrations of active oxygen forms, peroxides, and lipid peroxidation peroxidation products. This factor may make a certain contribution to the pathogenesis of endemic and goiter pathology of the thyroid.