Koida M, Yamamoto Y, Nakamuta H, Matsuo J, Okamoto M, Morimoto T, Seyler J K, Orlowski R C
Jpn J Pharmacol. 1982 Dec;32(6):981-6. doi: 10.1254/jjp.32.981.
It was found that salmon calcitonin-I (sCT) inhibited in vitro 45Ca2+-uptake by rat brain hypothalamus blocks in a dose-dependent manner. The minimum effective concentration was estimated to be 10 nM or less. The effect appeared to be specific to the hypothalamus and was not observed with the pons plus medulla oblongata or the cerebral cortex. Two C-terminal fragments of the fish hormone, sCT (10-32) and sCT (22-32), and porcine calcitonin failed to inhibit the ion-uptake though tested in concentrations abolishing 125I-sCT binding to these brain tissues, indicating that the whole structure of sCT is essential for the inhibitory effect but not for the binding. Another finding to be noted was a possible dependency of this effect on the integrity of the cell membrane structure. A crude synaptosomal fraction subsequently prepared from sCT-exposed hypothalamus blocks exhibited a decreased uptake of 45Ca2+, while a corresponding fraction from unexposed tissue did not respond to the hormone. These characteristics of this novel in vitro effect of sCT suggest its possible relevancy to the anorectic effect which also appears to be specific to the fish hormone.
研究发现，鲑鱼降钙素-I（sCT）在体外以剂量依赖性方式抑制大鼠脑下丘脑切片对45Ca2+的摄取。估计最小有效浓度为10 nM或更低。该作用似乎对下丘脑具有特异性，在脑桥加延髓或大脑皮层中未观察到。鱼激素sCT的两个C末端片段sCT（10-32）和sCT（22-32）以及猪降钙素，尽管在能消除125I-sCT与这些脑组织结合的浓度下进行了测试，但未能抑制离子摄取，这表明sCT的完整结构对于抑制作用是必不可少的，但对于结合作用并非如此。另一个需要注意的发现是这种作用可能依赖于细胞膜结构的完整性。随后从暴露于sCT的下丘脑切片制备的粗突触体部分对45Ca2+的摄取减少，而来自未暴露组织的相应部分对该激素无反应。sCT这种新的体外作用的这些特征表明其可能与厌食作用相关，厌食作用似乎也对鱼激素具有特异性。
