Effect of propylthiouracil on the level of Schiff's bases in tissues of rats on diet with different doses of potassium iodide.

OBJECTIVES: Iodide administration to animals, living in iodine-deficient areas, can induce oxidative processes in the thyroid gland and increase concentration of lipid peroxidation (LPO). Propylthiouracil (PTU)--a well-known antithyroid drug--may also act as an antioxidant. There are some reports, which consider the protective ability of this drug against LPO. The goal of the study was to evaluate oxidative processes and the protective role of PTU in three rat organs during treatment with pharmacological doses of iodide.

MATERIAL AND METHODS: Schiff's bases (SB) concentrations (a parameter of oxidative stress) were measured in liver, lung and kidney homogenates of male Wistar rats. For 2 weeks the animals received iodides in their diet in the following concentrations: Group 1--Controls (standard diet, approx. 0.7 mg of potassium iodide per kg; KI/kg); Group 2--diet containing 0.25 mg KI/kg; Group 3--diet with 4.0 mg KI/kg; Group 4--diet with 8.0 mg KI/kg. Group 5--standard diet with 0.1% of PTU in drinking water for two weeks. Subsequent tree groups (6-8) received KI in their diet in doses as above, respectively, together with PTU.

RESULTS: We noted increased SB levels in the lungs and in the liver, compared to those observed in the control group. We also found decreased SB concentrations in liver and lung homogenates after the administration of PTU but, unexpectedly, the level of SB increased in kidney homogenates of all the groups.

CONCLUSIONS: The results of this study indicate that iodine is involved in oxidative processes in different organs and PTU protects against iodine-induced oxidative stress.