NUCLEAR 3,5,3'-TRIIODOTHYRONINE (T-3) IN BROWN ADIPOSE-TISSUE - RECEPTOR OCCUPANCY AND SOURCES OF T-3 AS DETERMINED BY INVIVO TECHNIQUES
NUCLEAR 3,5,3'-TRIIODOTHYRONINE (T-3) IN BROWN ADIPOSE-TISSUE - RECEPTOR OCCUPANCY AND SOURCES OF T-3 AS DETERMINED BY INVIVO TECHNIQUES
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DOI：
10.1210/endo-120-1-55
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发表时间：
1987-01-01
期刊：
影响因子：
4.8
通讯作者：
SILVA, JE
中科院分区：
文献类型：
--
作者：
BIANCO, AC;SILVA, JE
用活体脉冲标记技术估计了棕色脂肪组织(BAT)中与高亲和力、低容量细胞核受体相关的T_3的数量和来源。通过体内饱和度分析测定最大结合容量。甲状腺功能正常大鼠在内源性T_3和T_4水平上的核受体占有率由示踪剂T_3和T_4的平衡核/血清比率以及注射示踪剂T_3和T_4后局部产生的核T_3/T_4比率来估计。这些比率分别乘以放射免疫法测量的内源性T3和T4浓度。最大结合容量为0.65ngT3/mg DNA，饱和度为71%。55%的核T3来自局部，45%来自循环T3。因此，BAT在受体数量上与肝脏相当(.apprx。5000个/细胞)，以及关于局部产生的T_3和血浆T_3对核T_3的饱和度和相对贡献。这些结果表明，BAT可能是甲状腺激素的一个重要靶点，与其他数据一起，该组织II型5‘’-脱碘酶活性的变化可能影响核T3受体的饱和。
The amount and sources of T3 associated with high affinity, low capacity cellular nuclear receptors in brown adipose tissue (BAT) have been estimated by in vivo pulse-labeling techniques. Maximal binding capacity was measured by in vivo saturation analysis. Nuclear receptor occupancy at endogenous levels of T3 and T4 in euthyroid rats was estimated from the equilibrium nuclear to serum ratio of tracer T3, and the locally generated nuclear T3 to serum T4 ratio after injecting tracer T3 and T4. These ratios were multiplied, respectively, by the endogenous concentrations of T3 and T4 as measured by RIA. The maximal binding capacity was 0.65 ng T3/mg DNA, and saturation was 71%. Fifty-five percent of the nuclear T3 was generated locally, and 45% was derived from circulating T3. BAT is, hence, comparable to the liver in number of receptors (.apprx. 5000/cell) and to the pituitary with regard to saturation and relative contributions of locally generated T3 and plasma T3 to nuclear T3. These results suggest that BAT may be an important target for thyroid hormones and, along with other data, that alterations in the activity of the type II 5''-deiodinase of this tissue may influence the saturation of nuclear T3 receptors.