Jolin T
Endocrinology. 1987 May;120(5):2144-51. doi: 10.1210/endo-120-5-2144.
The liver and kidney nuclear T3 content and the maximal nuclear T3-binding capacity (MBC) were measured 1 month after streptozotocin administration and compared with values in controls either fed ad libitum (C) or offered a restricted diet (FR). A group of insulin-treated diabetic (D+I) rats was also included. Plasma T4 and T3 concentrations decreased to low levels in diabetic (D) rats. Plasma T3 levels were decreased in FR rats, whereas circulating T4 was in the normal range for C animals. The MBC (nanograms of T3 per mg DNA) for liver and kidney nuclear T3 was determined by an in vivo saturation technique. The respective results for all groups were as follows (asterisks denote values differing from C with P values less than 0.05): C, 0.601 and 0.414; FR, 0.583 and 0.369; D, 0.310 and 0.220; D+I, 0.630 and 0.394. Nuclear T4 and T3 concentrations were determined by an isotopic equilibrium technique. Nuclear T3 (nanograms per mg DNA) for liver and kidney were, respectively, 0.298 and 0.176 for C, 0.208 and 0.135 for FR, 0.109 and 0.070 for D, and 0.270 and 0.168 for D+I rats. The decreased liver and kidney nuclear T3 content in D rats appears to be due to a marked reduction of their available intracellular T4 pool, from which T3 could be generated, but most likely represents a decreased T3 uptake into liver and kidney nuclei, as the nuclear to plasma ratios of labeled T3 were decreased in D rats. The low levels of T3 in nuclei of FR rats could be attributed to an inhibition of T4 to T3 conversion, since the intracellular pool of T4 appears to be normal. The possibility that diabetes and food restriction might affect the thyroid activity was examined by measurement of the activities of alpha-glycerophosphate dehydrogenase and cytosol malic enzyme, two liver and kidney enzymes regulated by thyroid hormone. Furthermore, although the measurements made in FR rats excluded the possibility that the alterations in MBC found in D animals were nutrition dependent, the reduced nuclear T3 content concomitant with food restriction may account for some of the quantitative changes in the alpha-glycerophosphate dehydrogenase and cytosol malic enzyme activity found in D rat tissues. In conclusion, the present findings suggest that the observed changes in indices of thyroid hormone action in liver and kidney of D rats could be related to alterations in nuclear T3 receptor concentrations and the concentration of T3 bound to the receptor.
在给予链脲佐菌素1个月后，测量肝脏和肾脏的核T3含量以及最大核T3结合能力（MBC），并与自由进食对照组（C）或限制饮食组（FR）的值进行比较。还纳入了一组胰岛素治疗的糖尿病（D + I）大鼠。糖尿病（D）大鼠的血浆T4和T3浓度降至低水平。FR大鼠的血浆T3水平降低，而循环T4在C组动物的正常范围内。肝脏和肾脏核T3的MBC（每毫克DNA中T3的纳克数）通过体内饱和技术测定。所有组的各自结果如下（星号表示与C组不同的值，P值小于0.05）：C组，0.601和0.414；FR组，0.583和0.369；D组，0.310和0.220；D + I组，0.630和0.394。核T4和T3浓度通过同位素平衡技术测定。肝脏和肾脏的核T3（每毫克DNA的纳克数），C组分别为0.298和0.176，FR组为0.208和0.135，D组为0.109和0.070，D + I组大鼠为0.270和0.168。D组大鼠肝脏和肾脏核T3含量的降低似乎是由于其可利用的细胞内T4池显著减少，T3可从中产生，但很可能代表肝脏和肾脏细胞核对T3的摄取减少，因为D组大鼠中标记T3的核与血浆比值降低。FR组大鼠细胞核中T3水平低可能归因于T4向T3转化的抑制，因为细胞内T4池似乎正常。通过测量α-甘油磷酸脱氢酶和胞质苹果酸酶的活性来研究糖尿病和食物限制可能影响甲状腺活性的可能性，这两种酶是肝脏和肾脏中受甲状腺激素调节的酶。此外，尽管对FR组大鼠的测量排除了D组动物中发现的MBC改变与营养有关的可能性，但与食物限制相关的核T3含量降低可能解释了D组大鼠组织中α-甘油磷酸脱氢酶和胞质苹果酸酶活性的一些定量变化。总之，目前的研究结果表明，D组大鼠肝脏和肾脏中甲状腺激素作用指标的观察到的变化可能与核T3受体浓度以及与受体结合的T3浓度的改变有关。
