Effect of thyroid status on catecholamine stimulation of thyroxine 5'-deiodinase in brown adipocytes.
Effect of thyroid status on catecholamine stimulation of thyroxine 5'-deiodinase in brown adipocytes.
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甲状腺状态对棕色脂肪细胞中儿茶酚胺刺激甲状腺素 5-脱碘酶的影响。
DOI：
10.1152/ajpendo.1989.256.1.e74
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发表时间：
1989
期刊：
影响因子：
--
通讯作者：
Larsen,PR
中科院分区：
文献类型：
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作者：
Mills,I;Raasmaja,A;Moolten,N;Lemack,G;Silva,JE;Larsen,PR
我们研究了肾上腺素能激动剂对甲状腺功能正常和甲状腺功能减退大鼠分散的棕色脂肪细胞中II型5 '-碘甲状腺原氨酸脱碘酶的激活作用。在甲状腺功能正常的细胞中，基础脱碘酶活性为30-100 fmol I-·h-1.10（6）cells-1，在去甲肾上腺素暴露期间增加4 - 5倍，阿普洛尔增强了这种作用。在甲状腺功能减退大鼠的细胞中，去甲肾上腺素引起的脱碘酶刺激比甲状腺功能正常的细胞大3 - 4倍，但阿普洛尔抑制了这种反应。在甲状腺功能正常的细胞，苯肾上腺素引起更大的刺激比去甲肾上腺素，但这是抑制阿普洛尔。异丙肾上腺素和8-溴腺苷3 '，5'-环一磷酸（8-BrcAMP）抑制苯肾上腺素反应，但单独使用时具有适度的刺激作用。尽管α 1-和β-肾上腺素能激动剂都适度增加了甲状腺功能减退细胞中的脱碘酶活性，但它们结合起来会产生显着的协同刺激。这种协同作用是由8-BrcAMP和毛喉素，以及异丙肾上腺素诱导。两种细胞类型中脱碘酶的刺激是由于Vmax增加而没有Km的改变和所需的mRNA合成。显着更大的脱碘酶反应的甲状腺功能减退的棕色脂肪细胞的儿茶酚胺可能有助于增强受损的产热反应，这一组织冷暴露。
We examined type II 5'-iodothyronine deiodinase activation by adrenergic agonists in dispersed brown adipocytes from euthyroid and hypothyroid rats. In euthyroid cells, basal deiodinase activity was 30-100 fmol I-.h-1.10(6) cells-1 and increased four- to fivefold during exposure to norepinephrine, an effect that was enhanced by alprenolol. In cells from hypothyroid rats, norepinephrine caused a three- to fourfold greater deiodinase stimulation than occurred in euthyroid cells but alprenolol inhibited the response. In euthyroid cells, phenylephrine caused greater stimulation than did norepinephrine, but this was inhibited by alprenolol. Isoproterenol and 8-bromoadenosine 3',5'-cyclic monophosphate (8-BrcAMP) inhibited the phenylephrine response but were modestly stimulatory alone. Although both alpha 1- and beta-adrenergic agonists increased deiodinase activity modestly in hypothyroid cells, in combination they caused a marked synergistic stimulation. This synergism was induced by 8-BrcAMP and forskolin, as well as by isoproterenol. The stimulation of deiodinase in both cell types was due to an increase in Vmax without an alteration in the Km and required mRNA synthesis. The markedly greater deiodinase response of the hypothyroid brown adipocyte to catecholamines may serve to enhance the impaired thermogenic response of this tissue to cold exposure.