TPA023 [7-(1,1-Dimethylethyl)-6-(2-ethyl-2<i>H</i>-1,2,4-triazol-3-ylmethoxy)-3-(2-fluorophenyl)-1,2,4-triazolo[4,3-<i>b</i>]pyridazine], an Agonist Selective for α2- and α3-Containing GABA<sub>A</sub>Receptors, Is a Nonsedating Anxiolytic in Rodents and Primates
作者:John R. Atack、Keith A. Wafford、Spencer J. Tye、Susan M. Cook、Bindi Sohal、Andrew Pike、Cyrille Sur、David Melillo、Linda Bristow、Fran Bromidge、Ian Ragan、Julie Kerby、Les Street、Robert Carling、José L. Castro、Paul Whiting、Gerard R. Dawson、Ruth M. McKernan
DOI:10.1124/jpet.105.089920
日期:2006.1
7-(1,1-Dimethylethyl)-6-(2-ethyl-2 H -1,2,4-triazol-3-ylmethoxy)-3-(2-fluorophenyl)-1,2,4-triazolo[4,3- b ]pyridazine (TPA023) is a triazolopyridazine that binds with equivalent high (subnanomolar) affinity to the benzodiazepine binding site of recombinant human GABAA receptors containing an α1, α2, α3, or α5 subunit but has partial agonist efficacy at the α2 and α3 subtypes and essentially antagonist efficacy at the α1 and α5 subtypes. In rats, TPA023 gave time- and dose-dependent occupancy after oral dosing, with 50% occupancy corresponding to a dose of 0.42 mg/kg. It has anxiolytic-like activity in unconditioned (elevated plus maze) and conditioned (fear-potentiated startle and conditioned suppression of drinking) rat models of anxiety with minimum effective doses (MED; 1–3 mg/kg) corresponding to 70 to 88% occupancy. However, there was no appreciable sedation in a response sensitivity (chain-pulling) assay at a dose of 30 mg/kg, resulting in 99% occupancy. Similarly, TPA023 was robustly anxiolytic in the squirrel monkey conditioned emotional response assay, with a MED of 0.3 mg/kg, but did not produce any sedation in a lever-pressing test of sedation even at 10 mg/kg. TPA023 produced no impairment in performance in the mouse Rotarod assay, and there was only a mild interaction with ethanol. In addition to anxiolytic-like efficacy, TPA023 had anticonvulsant activity in a mouse pentylenetetrazole seizure model. Finally, TPA023 did not cause precipitated withdrawal in mice treated for 7 days with the nonselective agonist triazolam, nor did N -methyl-β-carboline-3-carboxamide (FG 7142) precipitate withdrawal in mice treated for 7 days with TPA023. In summary, the novel α2/α3-selective efficacy profile of TPA023 translates into a nonsedating anxiolytic profile that is distinct from nonselective agonists.
7-(1,1-二甲基乙基)-6-(2-乙基-2 H-1,2,4-三唑-3-基甲氧基)-3-(2-氟苯基)-1,2,4-三唑并[4,3- b ]哒嗪(TPA023)是一种三唑并哒嗪,能以相当高(亚纳摩尔)的亲和力与含有α1、α2、α3或α5亚基的重组人GABAA受体的苯并二氮杂卓结合位点结合,但对α2和α3亚基有部分激动剂功效,对α1、α2、α3或α5亚基有部分激动剂功效、α2、α3 或 α5亚基的重组人 GABAA 受体结合位点的苯并二氮杂卓亲和力(亚纳摩尔),但对α2 和 α3亚型有部分激动剂功效,对α1 和 α5亚型基本上有拮抗剂功效。在大鼠体内,TPA023 口服后会产生与时间和剂量相关的作用,0.42 毫克/千克的剂量会产生 50%的作用。在大鼠无条件焦虑模型(高架加迷宫)和条件焦虑模型(恐惧诱发惊吓和条件抑制饮水)中,TPA023具有抗焦虑样活性,最低有效剂量(MED;1-3 毫克/千克)的作用率为 70% 至 88%。然而,在反应敏感性(拉链)试验中,剂量为 30 毫克/千克时没有明显的镇静作用,作用率为 99%。同样,在松鼠猴条件性情绪反应试验中,TPA023 具有很强的抗焦虑作用,MED 为 0.3 毫克/千克,但在按压杠杆镇静试验中,即使剂量为 10 毫克/千克,也不会产生任何镇静作用。TPA023 在小鼠旋转木马试验中不会损害小鼠的表现,而且与乙醇只有轻微的相互作用。除了抗焦虑药效外,TPA023 还在小鼠戊四唑癫痫模型中具有抗惊厥活性。最后,用非选择性激动剂三唑仑治疗小鼠 7 天后,TPA023 不会导致小鼠出现戒断沉淀;用 TPA023 治疗小鼠 7 天后,N-甲基-β-咔啉-3-甲酰胺(FG 7142)也不会导致小鼠出现戒断沉淀。总之,TPA023 的新型 α2/α3 选择性药效特征转化为一种非镇静性抗焦虑药效特征,有别于非选择性激动剂。