Gabazine, a γ-aminobutyric acid type A (GABAA) receptor antagonist, has previously been reported to inhibit the binding of [3H]NCS-382, a representative ligand of the high-affinity binding site for the neuroactive substance γ-hydroxybutyric acid (GHB). We herein report a study on the structural determinants of gabazine for binding to (i) the orthosteric binding site of the GABAA receptor and (ii) the high-affinity GHB binding site. Expanding the structural diversity of available ligands for the high-affinity GHB binding sites, this study identified 2-(imidazo[1,2- b]pyridazin-2-yl)acetic acid as a novel ligand-scaffold leading to analogues with relatively high affinity ( Ki 0.19-2.19 μM) and >50 times selectivity for the [3H]NCS-382 over [3H]muscimol binding sites. These results highlight that gabazine interacts with the high-affinity GHB and orthosteric GABAA receptor binding sites differently and that distinct analogues can be generated to select between them. To facilitate further in vivo studies, a promising prodrug candidate for brain delivery was identified.

中文翻译：

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发现2-（咪唑并[1,2-b]哒嗪-2-基）乙酸作为对γ-羟基丁酸（GHB）高亲和力结合位点有选择性的新型配体。

以前曾报道过一种新的加巴嗪（一种γ-氨基丁酸（GABAA）受体拮抗剂）抑制[3H] NCS-382的结合，这是神经活性物质γ-羟基丁酸的高亲和力结合位点的代表性配体（ GHB）。我们在本文中报告了关于丙巴嗪与（i）GABAA受体的正构结合位点和（ii）高亲和力GHB结合位点结合的结构决定簇的研究。这项研究扩大了用于高亲和力GHB结合位点的可用配体的结构多样性，确定了2-（咪唑并[1,2-b]哒嗪-2-基）乙酸是一种新型的配体骨架，可产生相对较高的类似物[3H] NCS-382对[3H] muscimol结合位点的亲和力（Ki 0.19-2.19μM）和> 50倍的选择性。这些结果表明，加巴嗪与高亲和力GHB和正构GABAA受体结合位点的相互作用不同，并且可以生成不同的类似物以在它们之间进行选择。为了促进进一步的体内研究，鉴定了有希望的前药候选物用于脑部递送。