[Liver deiodinase activity in rats after high and low fat iodine deficient diets]

Male Wistar rats were restricted on iodine intake by feeding pure diets, without iodine addition. The high fat diet contained 50% fat (HFD), the low fat diet 3% fat (LFD). Control animals received the same diets, but with iodine addition. After feeding the diets for 7 or 19 weeks liver deiodinase activity was estimated. The iodine deficient animals showed a diminished enzyme activity in both diet groups. But after feeding the diet without iodine addition for 7 weeks the deiodinase activity significantly decreased in the HFD-group only in relation to liver weight per 100 g body weight. After 19 weeks the liver deiodinase activity in the HFD-group was diminished significantly, but the decrease was much smaller than in the LFD-group. The estimation of relative thyroid weight and iodoamino acid distribution demonstrate that the level of iodine deficiency was in iodine restricted HFD-rats greater than in appropriate LFD-rats. This result was verified by investigations of thyroidal radio iodine uptake and iodine content, PB131I, serum iodine and T4 levels in both diet groups. The reason for the lower decrease of deiodinase activity at higher iodine deficiency in HFD-rats as compared to LFD-rats and the possible importance of food enriched with fat in endemic goiter areas is discussed.