ICEECE2012 Poster Presentations Thyroid (non-cancer) (188 abstracts)
1Medical University of Lodz, Lodz, Poland; 2Polish Mothers Memorial Hospital Research Institute, Lodz, Poland.
Introduction: Fenton reaction (Fe2++H2O2 →Fe3++ ′OH+OH−) is of special significance in the thyroid gland, as both its substrates, i.e. H2O2 and Fe2+, are required for thyroid hormone synthesis. Also iodine, an essential element supplied by the diet, is indispensable for thyroid hormone synthesis. It is well known that iodine affects red-ox balance. One of the most frequently examined oxidative processes is lipid peroxidation (LPO), which results from oxidative damage to membrane lipids.
The aim of the study was to evaluate effects of iodine, used as potassium iodide (KI) or potassium iodate (KIO3), on LPO in porcine thyroid homogenates under basal conditions and in the presence of Fenton reaction substrates.
Methods: Porcine thyroid homogenates were incubated in the presence of KI (0.00005500 mM) or KIO3 (0.00005200 mM), without or with addition of FeSO4 (30 μM) +H2O2 (0.5 mM). Concentration of malondialdehyde+4-hydroxyalkenals (MDA+4-HDA) was measured spectrophotometrically, as an index of LPO.
Results: Potassium iodide, used in the lowest concentrations (≤0.05 mM), did not affect LPO; KI in concentrations of 0.11.0 mM, resulting in thyroid level of inorganic iodine close to that observed under normal iodine supply, clearly decreased the basal LPO; in the highest concentrations of 10500 mM, KI increased LPO. At the same time, KI used in the middle range of concentrations (1050 mM) reduced Fenton reaction-induced LPO. In opposite, KIO3 revealed, depending on the concentration, either no protective effect at all or even strong prooxidative action.
Conclusion: Potassium iodide, used in doses generally recommended in iodide prophylaxis, may prevent oxidative damage to membrane lipids in porcine thyroid. Toxic effects of iodide overload may result from its prooxidative action. Potassium iodate does not possess any direct beneficial effects on red-ox balance in the thyroid, which constitutes an additional argument against its utility in iodine prophylaxis.
Declaration of interest: The authors declare that there is no conflict of interest that could be perceived as prejudicing the impartiality of the research project.
Funding: This work was supported, however funding details unavailable.