Regulation of iodothyronine 5'-deiodination in lean and obese (ob/ob) mice.
Regulation of iodothyronine 5'-deiodination in lean and obese (ob/ob) mice.
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瘦小鼠和肥胖小鼠 (ob/ob) 中碘甲状腺原氨酸 5-脱碘的调节。
DOI：
10.1152/ajpendo.1985.249.2.e209
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发表时间：
1985
期刊：
影响因子：
--
通讯作者：
Romsos,DR
中科院分区：
文献类型：
--
作者：
Hillgartner,FB;Romsos,DR
肥胖(ob/ob)小鼠表现出寒冷和饮食诱导的产热功能受损，这可能部分是由于甲状腺激素在外周脱碘水平上的作用缺陷，即甲状腺激素将甲状腺激素(T4)脱碘为3，5，3‘-三碘甲状腺原氨酸(T3)。通过比较瘦小鼠和肥胖小鼠在不同生理条件下肝和肾微粒体中5‘-脱碘(5’-D)的动力学参数，验证后一种可能性。5‘-D对年龄(1至8-10wk)、环境温度(14、25和33摄氏度)以及瘦小鼠和肥胖小鼠甲状腺激素状态的变化具有适应性。然而，酶反应的大小因表型而异。5‘-D对年龄和环境温度的反应也取决于组织类型，表明肝脏和肾脏可能存在不同的5’-D同工酶。在25摄氏度的基础条件下，肥胖小鼠的肝和肾最大5‘-D低于瘦小鼠。Vmax的差异早在1周龄就观察到了。瘦小鼠和肥胖小鼠5‘-D的Km值相似。这些发现表明，肥胖小鼠体内产热靶组织的T3供应可能受到损害，这可能是导致这些动物甲状腺激素表达和产热减少的原因之一。
Obese (ob/ob) mice exhibit impaired cold- and diet-induced thermogenesis, which may result in part from a defect in thyroid hormone action at the level of peripheral deiodination of thyroxine (T4) to 3,5,3'-triiodothyronine (T3). The latter possibility was examined by comparing kinetic parameters of 5'-deiodination (5'-D) in hepatic and renal microsomes of lean and obese mice during various physiological conditions. 5'-D Was adaptive to changes in age (1 to 8-10 wk), environmental temperature (14, 25, and 33 degrees C), and thyroid hormone status in both lean and obese mice. The magnitude of enzyme response, however, varied between phenotypes. 5'-D Response to age and environmental temperature was also dependent on tissue type, indicating that different isozymes for 5'-D may exist in liver and kidney. Under basal conditions at 25 degrees C, maximal hepatic and renal 5'-D was lower in obese mice than in lean mice. Differences in Vmax were observed as early as 1 wk of age. Km values for 5'-D were similar in lean and obese mice. These findings suggest that T3 availability to thermogenic target tissues may be impaired in obese mice, which may contribute to diminished thyroid hormone expression and heat production in these animals.