THYROID PEROXIDASE ACTIVITY IN IODINE DEFICIENT RATS

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Abstract
The evolution of peroxidase activity was followed during the course of iodine deficiency in the rat. The enzymatic activity was determined in vitro by oxidation of iodide or by iodination of bovine serum albumin using a peroxide-generating system. An inverse relationship between the stable iodine content in the gland and the peroxidase activity is observed; this relation is not linear and the highest increase is found when the iodine content in the gland is below 5 .mu.g/thyroid gland at 35 days of the treatment. In animals maintained on a low iodine diet, a triphasic effect on enzymatic activity is observed: early (10 and 20 days) and late (70 and 80 days) effects when the increase in peroxidase activity is 3 times higher than the increase in weight, DNA and total protein content: and an intermediar effect (between 20 and 70 days) when the peroxidase activity stays approximately at the same level. In any case, the enzymatic activity increases to a greater extent than does thyroid weight, and total protein and DNA content, suggesting that high cellular activity is due to a specific enzyme induction comparable to that obtained recently in human sporadic goiter.