Tissue-specific regulation of fatty acid synthesis by thyroid hormone.
Tissue-specific regulation of fatty acid synthesis by thyroid hormone.
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DOI：
10.1210/endo.130.2.1733712
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发表时间：
1992-02
期刊：
影响因子：
4.8
通讯作者：
B. Blennemann;Y K Moon;H. Freake
中科院分区：
文献类型：
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作者：
B. Blennemann;Y K Moon;H. Freake
一般认为甲状腺激素刺激大鼠肝脏合成长链脂肪酸。然而，关于其在白色脂肪组织中的作用存在相互矛盾的数据，而在棕色脂肪组织中，甲状腺功能减退动物的脂肪生成率最高。我们系统地研究了甲状腺状态对大鼠不同组织脂肪生成的影响。脂肪酸合成进行了评估，在体内，使用氚水的掺入。在甲状腺功能减退（4.1 +/- 0.6微米H/g. h）和甲状腺功能亢进大鼠（66.5 +/- 13.2微米H/g. h）之间，肝脏脂肪生成诱导了16倍。肾脏和心脏的脂肪生成活性要低得多，但对甲状腺激素也有积极的反应。甲状腺功能亢进和甲状腺功能减退都减少了腹膜后脂肪的脂肪酸合成，对附睾脂肪的影响相似，但不显著。然而，从甲状腺功能亢进的大鼠和体外培养的附睾脂肪细胞的脂肪生成活性是甲状腺功能减退或甲状腺功能正常的动物细胞的3倍。当以每克组织计算时，甲亢大鼠皮下脂肪中的脂肪生成增强，但当以每整个组织计算时则无差异。在棕色脂肪组织中，脂肪生成与甲状腺激素状态呈负相关。脑、肺、皮肤、骨骼和肌肉中的脂肪酸合成对甲状腺状态的变化没有反应。TLC证实，超过90%的掺入的氚在脂肪酸中。因此，在甲状腺功能减退的动物中，脂肪生成主要发生在皮肤、骨骼、肌肉和其他无反应器官中，而在甲状腺功能亢进的大鼠中，仅肝脏就构成了几乎一半的脂肪酸合成。脂肪酸合成途径为研究甲状腺激素对基因表达的组织特异性调节提供了一个很好的模型。
It is generally agreed that thyroid hormone stimulates the hepatic synthesis of long chain fatty acids in the rat. However, there are conflicting data about its effects in white adipose tissue, while in brown adipose tissue, lipogenic rates are highest in hypothyroid animals. We have systematically examined the effect of thyroid state on lipogenesis in different rat tissues. Fatty acid synthesis was assessed in vivo, using the incorporation of tritiated water. Hepatic lipogenesis was induced 16-fold between hypothyroid (4.1 +/- 0.6 microns H incorporated/g.h) and hyperthyroid rats (66.5 +/- 13.2 microns H/g.h). Kidney and heart were much less lipogenically active, but also responded positively to thyroid hormone. Both hyper- and hypothyroidism diminished fatty acid synthesis in retroperitoneal fat and had similar, although not significant, effects in epididymal fat. However, epididymal adipocytes, taken from hyperthyroid rats and cultured in vitro, were 3 times more lipogenically active than cells from either hypo- or euthyroid animals. Lipogenesis in sc fat from hyperthyroid rats was enhanced when calculated per g tissue, but was not different when expressed per whole tissue. In brown adipose tissue, lipogenesis was inversely related to thyroid hormone status. Fatty acid synthesis in brain, lung, skin, and bone and muscle did not respond to changes in thyroid state. TLC confirmed that greater than 90% of the incorporated tritium was in fatty acids. Thus, in hypothyroid animals, lipogenesis primarily occurs in skin, bone, muscle, and other nonresponsive organs, whereas in hyperthyroid rats, the liver alone constitutes almost half of all fatty acid synthesis. The fatty acid synthetic pathway provides an excellent model for examining the tissue-specific regulation of gene expression by thyroid hormone.