Thyroid hormone nuclear receptors in skeletal muscle as influenced by environmental temperature and energy intake

Young litter-mate pigs were kept at either 10 or 35 degrees C and fed either a high (H) or a low (L) food intake producing four groups: 10 H, 10 L, 35 H and 35 L. The numbers of receptors for thyroid hormone in the nuclei of skeletal muscle were estimated and found to be greatest in the 35 H group and least in the 10 L group. The numbers of receptors in the 10 H and 35 L groups were similar and took intermediate values. It is suggested that the differences in receptor numbers represent an adaptation which regulates the tissue response to thyroid hormone. Some possible consequences of this adaptation are discussed.