Unger J, Van Sande J
Mol Cell Endocrinol. 1987 Jul;52(1-2):115-23. doi: 10.1016/0303-7207(87)90104-3.
Nonbutanol-extractable 131I (NBE131I) release by dog thyroid slices in vitro has been shown previously to be primarily thyroglobulin (Tg); it is stimulated by TSH. NBE131I (Tg) release has therefore been considered as an in vitro model of thyroglobulin secretion and was further characterized in this work. TSH-stimulated NBE131I (Tg) release, like TSH-stimulated BE131I (T4, T3 and iodide) release was reproduced by forskolin, an activator of adenylate cyclase. TSH-, (Bu)2cAMP- and forskolin-stimulated NBE131I (Tg) release was inhibited by 10(-5) M carbamylcholine, an effect relieved by 10(-5) M atropine, but not by 10(-4) M 1-methyl-3-isobutylxanthine. NBE131I (Tg) release was observed in the presence of 2 mM methimazole and 2 mM perchlorate. Cooling the slices to 20 degrees C or addition of 10(-5) M monensin completely blocked the formation of apical pseudopods and BE131I release but not NBE131I (Tg) release. Inhibition by 500 microM chloroquine of intralysosomal Tg hydrolysis and BE131I release did not enhance NBE131I (Tg) release. Cytochalasin B induced a concentration-dependent increase in basal and TSH-stimulated NBE131I (Tg) release at concentrations which depressed TSH-stimulated BE131I release. Removal of Ca2+ from the medium and slices by 10(-3) M or 10(-4) M EGTA increased NBE131I (Tg) release. In conclusion, in dog thyroid slices, TSH-stimulated NBE131I (Tg) release was mediated by cAMP and inhibited by 10(-5) M carbamylcholine at a step beyond cAMP. It was not neosynthesized Tg. It did not seem to require the formation of apical pseudopods or to result from the escape from lysosomes of undegraded thyroglobulin.(ABSTRACT TRUNCATED AT 250 WORDS)
先前已表明，犬甲状腺切片体外释放的非丁醇可提取的131I（NBE131I）主要是甲状腺球蛋白（Tg）；它受促甲状腺激素（TSH）刺激。因此，NBE131I（Tg）释放被视为甲状腺球蛋白分泌的体外模型，并在本研究中进一步进行了特性分析。TSH刺激的NBE131I（Tg）释放，与TSH刺激的BE131I（T4、T3和碘化物）释放一样，可被腺苷酸环化酶激活剂福斯可林重现。TSH、（Bu）2cAMP和福斯可林刺激的NBE131I（Tg）释放受到10（-5）M氨甲酰胆碱的抑制，10（-5）M阿托品可缓解此效应，但10（-4）M 1-甲基-3-异丁基黄嘌呤则不能。在2 mM甲巯咪唑和2 mM高氯酸盐存在的情况下观察到NBE131I（Tg）释放。将切片冷却至20摄氏度或添加10（-5）M莫能菌素可完全阻断顶端伪足的形成和BE131I释放，但不影响NBE131I（Tg）释放。500 microM氯喹对溶酶体内Tg水解和BE131I释放的抑制并未增强NBE131I（Tg）释放。细胞松弛素B在抑制TSH刺激的BE131I释放的浓度下，诱导基础和TSH刺激的NBE131I（Tg）释放呈浓度依赖性增加。用10（-3）M或10（-4）M乙二醇双四乙酸（EGTA）从培养基和切片中去除Ca2+可增加NBE131I（Tg）释放。总之，在犬甲状腺切片中，TSH刺激的NBE131I（Tg）释放由cAMP介导，并在cAMP之后的步骤受到10（-5）M氨甲酰胆碱的抑制。它不是新合成的Tg。它似乎不需要顶端伪足的形成，也不是未降解甲状腺球蛋白从溶酶体中逸出的结果。（摘要截短至250字）
