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.

Influence of zinc on the status of hepatic trace elements and biokinetics of 65Zn in ethanol treated rats.

Whole body counting studies of 65Zn indicated that the Tb1 (the faster component) was significantly decreased while the slower component (Tb2) was increased significantly following ethanol treatment. Interestingly, following zinc treatment to ethanol treated rats, slower component (Tb2) of 65Zn came back to within normal limits while the faster component (Tb1) got significantly elevated in comparison to ethanol treatment. Percent uptake values of 65Zn were found to be increased in liver, intestine, muscle, brain and kidney, and decreased in bone under alcoholic conditions. Interestingly, the uptake values of 65Zn in all the organs except muscle were reverted back to within normal limits upon zinc supplementation to these ethanol intoxicated animals. A significant decrease in zinc contents was noticed in ethanol treated rats, which, however, were raised to normal levels upon zinc supplementation: Copper levels, on the other hand, were significantly enhanced in both ethanol fed and combined ethanol + zinc treated rats. Calcium levels were significantly decreased in both ethanol and zinc treated rats, which however were further reduced upon zinc supplementation to ethanol fed rats. However, no significant change was observed in the concentrations of sodium and potassium in any of the treatment groups. In conclusion, zinc appears to play a protective role by normalizing the turnover of 65Zn in whole body as well as in its uptake in different organs under alcoholic conditions.