Robinson T, MacAllan D, Lunt G, Battersby M
J Neurochem. 1986 Dec;47(6):1955-62. doi: 10.1111/j.1471-4159.1986.tb13114.x.
The specific binding of [N-methyl-3H]flunitrazepam ([3H]FNZP) to a membrane fraction from the supraoesophageal ganglion of the locust (Schistocerca gregaria) has been measured. The ligand binds reversibly with a KD of 47 nM. The binding is Ca2+-dependent, a property not found for the equivalent binding site in vertebrate brain. The pharmacological characteristics of the locust binding site show similarities to both central and peripheral benzodiazepine receptors in mammals. Thus binding is enhanced by gamma-aminobutyric acid (GABA), a feature of mammalian central receptors, whereas the ligand Ro 5-4864 was more effective in displacing [3H]FNZP than was clonazepam, which is the pattern seen in mammalian peripheral receptors. The locust benzodiazepine binding site was photoaffinity-labelled by [3H]FNZP, and two major proteins of Mr 45K and 59K were specifically labelled. In parallel experiments with rat brain membranes a single major protein of Mr 49K was labelled, a finding in keeping with many reports in the literature. We suggest that the FNZP binding site described here is part of the GABA receptor complex of locust ganglia. The insect receptor appears to have the same general organization as its mammalian counterpart but differs significantly in its detailed properties.
已测定了[甲基 - ³H]氟硝西泮（[³H]FNZP）与蝗虫（沙漠蝗）食管上神经节膜部分的特异性结合。该配体以47 nM的解离常数（KD）可逆性结合。这种结合是Ca²⁺依赖性的，这一特性在脊椎动物脑中的等效结合位点未被发现。蝗虫结合位点的药理学特性显示出与哺乳动物中枢和外周苯二氮䓬受体都有相似之处。因此，γ-氨基丁酸（GABA）可增强结合，这是哺乳动物中枢受体的一个特征，而配体Ro 5 - 4864在取代[³H]FNZP方面比氯硝西泮更有效，这是在哺乳动物外周受体中看到的模式。蝗虫苯二氮䓬结合位点被[³H]FNZP光亲和标记，并且特异性标记了分子量为45K和59K的两种主要蛋白质。在与大鼠脑膜的平行实验中，标记了一种分子量为49K的单一主要蛋白质，这一发现与文献中的许多报道一致。我们认为这里描述的FNZP结合位点是蝗虫神经节GABA受体复合物的一部分。昆虫受体似乎与其哺乳动物对应物具有相同的总体结构，但在其详细特性上有显著差异。
