Zahniser N R, Goens M B, Hanaway P J, Vinych J V
J Neurochem. 1984 May;42(5):1354-62. doi: 10.1111/j.1471-4159.1984.tb02795.x.
An in vitro receptor binding assay, using filtration to separate bound from free [125I]insulin, was developed and used to characterize insulin receptors on membranes isolated from specific areas of rat brain. The kinetic and equilibrium binding properties of central receptors were similar to those of hepatic receptors. The binding profiles in all tissues were complex and were consistent with binding in multiple steps or to multiple sites. Similar binding properties were found among receptors in olfactory tubercle/bulb, cerebral cortex, hippocampus, striatum, hypothalamus, and cerebellum. High affinity [125I]insulin binding sites (KD = 3-11 nM) were distributed evenly between membranes isolated from P1 and P2 fractions of these brain areas, with the exception of the olfactory tubercle in which binding to P2 membranes was four-fold greater (Bmax = 150 fmol/mg protein). One difference between insulin receptors in brain and peripheral target tissues, however, was observed. Following exposure to 0.17 microM insulin for 3 h at 37 degrees C, the number of specific [125I]insulin binding sites on adipocytes decreased by 40%, while the number of binding sites on minces of cerebral cortex/olfactory tubercle remained constant. The results suggest that although the binding characteristics of central and peripheral insulin receptors are similar, these receptors do not appear to be regulated in the same manner.
我们开发了一种体外受体结合试验，利用过滤法分离结合态与游离态的[125I]胰岛素，并用于表征从大鼠脑特定区域分离的膜上的胰岛素受体。中枢受体的动力学和平衡结合特性与肝受体相似。所有组织中的结合曲线都很复杂，与多步结合或与多个位点结合一致。在嗅结节/嗅球、大脑皮层、海马体、纹状体、下丘脑和小脑中的受体之间发现了相似的结合特性。高亲和力的[125I]胰岛素结合位点（KD = 3 - 11 nM）均匀分布于从这些脑区的P1和P2组分分离的膜之间，但嗅结节除外，其中与P2膜的结合力大四倍（Bmax = 150 fmol/mg蛋白）。然而，观察到脑内胰岛素受体与外周靶组织中的胰岛素受体之间存在一个差异。在37℃下用0.17 microM胰岛素处理3小时后，脂肪细胞上特异性[125I]胰岛素结合位点的数量减少了40%，而大脑皮层/嗅结节碎块上的结合位点数量保持不变。结果表明，虽然中枢和外周胰岛素受体的结合特性相似，但这些受体的调节方式似乎不同。
