Influence of dietary linoleic acid (18:2, n6) on the effects of hyperthyroidism in Mus musculus

This investigation was stimulated by the earlier findings of Ershoff (1949). He reported that a diet containing 45% (w/w) full fat soybean meal counteracted the weight loss and other effects of hyperthyroidism on the gross appearance (for example scaly skin and hair loss) of the immature rats. However, he observed that this dietary treatment did not have any effect on the increased oxygen consumption caused by thyroid hormone treatment. More recent studies have shown that unsaturated fatty acids inhibit thyroid hormone binding to nucleus (Van der Klis, 1989, Inoue et al., 1989, Wiersinga and Platvoet-Ter-Schiphorst, 1990). It has also been suggested that unsaturated free fatty acids in high concentrations may reduce the binding of thyroid hormones to plasma proteins resulting in an increase in their free level in the plasma (Lim et al., 1988). Benvenga et al., (1987) observed an increase in the plasma concentration of T4 when the ratio of free unsaturated fatty acid / thyroxine binding globulin was increased. These reports indicated a connection between polyunsaturated fatty acids and effects of thyroid hormones. Hyperthyroidism is the most common endocrine disorder next to diabetes mellitus (Sterling, 1975). The treatment of this condition basically involves prolonged drug therapies, partial or total thyroidectomy or radioiodine treatment. The aim of this investigation was also to explore a possibility of a dietary treatment, if polyunsaturated fatty acids exert an effect on thyroid hormone action