Radioprotective role of zinc following single dose radioiodine (131I) exposure to red blood cells of rats.

BACKGROUND & OBJECTIVES Irradiation with 131I is used for the treatment of various thyroid disorders. It is likely that radioiodine while in systemic circulation may cause some adverse effects on antioxidative enzymes present in red blood cells (RBCs). Zinc, on the other hand, has been reported to maintain the integrity of cells under certain toxic conditions. The present study was conducted to evaluate the adverse effects of 131I on RBCs and also to assess the protection provided by zinc under these conditions. METHODS Female Wistar rats (n=32) were divided into four groups. Animals in group I served as normal controls; group II animals were administered a dose of 3.7 Mbq of 131I (carrier-free) intraperitoneally, group III animals were supplemented with zinc (227 mg/l drinking water) and animals in group IV were given a combined treatment of zinc as well as 131I. Activities of antioxidant enzymes were assessed in erythrocyte lysates after two days of treatments. RESULTS An increase in the activity of glutathione reductase (GR), superoxide dismutase (SOD), reduced glutathione (GSH) and malondialdehyde (MDA) in the lysates of erythrocytes was seen after two days of exposure from 131I radiations. However, the activity of catalase was found to be significantly decreased. Interestingly, zinc supplementation to 131I treated rats resulted in attenuating the adverse effects caused by 131I on the levels of antioxidative enzymes. INTERPRETATION & CONCLUSION 131I can induce significant oxidant/antioxidant changes in RBCs and zinc may prove to be a candidate with great promise for radioprotection.