Selenium deficiency aggravates the necrotizing effects of a high iodide dose in iodine deficient rats

The effect of selenium deficiency associated with various iodide intake was investigated in rats in order to better understand its possible role in the etiopathogeny of myxedematous cretinism. Groups of rat pups were fed from birth a low selenium diet (Se-) and submitted to goitrogenic treatment (1% perchlorate in water) for one month. Some animals were refed iodide after perchlorate withdrawal. The gland morphology was analyzed in correlation with the glutathione peroxidase (GPX) activity and the thyroid hormone plasma levels. In all Se- rats, the GPX activity was strongly reduced as compared to selenium sufficient (Se+) animals (P < 0.01). Goitrous rats were hypothyroid whatever the selenium intake. After iodide refeeding, plasma T4 and T3 levels were increased by 160% in Se- rats and by respectively 330% and 580% in Se+ rats. The thyroid morphology was different according to the selenium intake: necrotic cells were about three times more numerous in Se- than in Se+ rats (P < 0.01) and the inflammatory reaction was increased. These experimental data demonstrate the detrimental role of selenium deficiency in one experimental case of thyroid disease. Such reduction of cell defences could contribute to the thyroid failure of African myxedematous cretins.