Pharmacological characterization of a novel cell line expressing human α4β3δ GABAA receptors
Pharmacological characterization of a novel cell line expressing human α4β3δ GABAA receptors
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DOI：
10.1038/sj.bjp.0704795
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发表时间：
2002-08-01
影响因子：
7.3
通讯作者：
Wafford, KA
中科院分区：
文献类型：
--
作者：
Brown, N;Kerby, J;Wafford, KA
1 使用全细胞膜片钳技术研究了表达人 alpha(4)beta(3)delta GABA(A) 受体的稳定细胞系的药理学。2 与 alpha(4)beta(3)gamma(2) 受体相比，alpha(4)beta(3)delta 受体对 GABA 的敏感性更高，EC50 为 0.50 (0.46, 0.53) 分别为μM和2.6（2.5，2.6）μM。此外，GABA 部分激动剂哌啶-4-磺酸盐 (P4S) 和 4,5,6,7-四氢异噻唑并-[5,4-c]吡啶-3-醇 (THIP) 对 α(4)β(3)δ 受体表现出明显更高的功效，事实上，THIP 对这些受体表现出比 GABA 更大的功效。 3 亚基赋予 GABA 缓慢脱敏作用，α(4)beta(3)delta 的速率常数为 4.8 +/- 0.5 s，α(4)beta(3)gamma(2) 的速率常数为 2.5 +/- 0.2 s。然而，P4S 和 THIP 对两种受体亚型表现出相似的脱敏水平，表明这种效应是激动剂特异性的。4 α(4)beta(3)delta 和 alpha(4)beta(3)gamma(2) 对阳离子锌 (2-3 muM IC50) 的抑制表现出相同的敏感性。然而，α(4)β(3)δ 受体对镧的抑制表现出更高的敏感性。 GABA 拮抗剂 SR-95531 和印防己毒素的 IC50 与 alpha(4)beta(3)delta 和 alpha(4)beta(3)gamma(2) 相似。同样，在高和低 pH 条件下都观察到两种亚型的抑制作用。5 α(4)β(3)δ 受体对苯二氮卓配体的调节不敏感。相比之下，Ro15-4513 和 Bretazenil 增强了 α(4)β(3)γ(2) 细胞上的 GABA 反应，反向激动剂 DMCM 显示了 α(4)β(3)γ(2) 受体的变构抑制。 6 神经类固醇对 α(4)β(3)δ 受体的功效大大增强。 在 alpha(4)beta(3)gamma(2) 受体上观察到的结果。使用 THDOC 观察到的效果最大，对 alpha(4)beta(3)delta 增强 524+/-71.6%，对 alpha(4)beta(3)gamma(2) 受体增强 297.9 +/- 49.7%。然而，类固醇孕烯醇酮硫酸盐的抑制没有表现出亚型选择性。与 alpha(4)beta(3)gamma(2) 受体相比，戊巴比妥和丙泊酚在 alpha(4)beta(3)delta 受体上的疗效略有增强，而依托咪酯则大大增强。7 我们表明 alpha(4)beta(3)delta 受体具有独特的药理学和动力学特征。由于其在大脑内的有限分布和独特的药理学，该受体可能在神经类固醇和麻醉剂的作用中发挥重要作用。
1 The pharmacology of the stable cell line expressing human alpha(4)beta(3)delta GABA(A) receptor was investigated using whole-cell patch-clamp techniques.2 alpha(4)beta(3)delta receptors exhibited increased sensitivity to GABA when compared to alpha(4)beta(3)gamma(2) receptors, with EC50's of 0.50 (0.46, 0.53) muM and 2.6 (2.5, 2.6) muM respectively. Additionally, the GABA partial agonists piperidine-4-sulphonate (P4S) and 4,5,6,7-tetrahydroisothiazolo-[5,4-c]pyridin-3-ol (THIP) displayed markedly higher efficacy at alpha(4)beta(3)delta receptors, indeed THIP demonstrated greater efficacy than GABA at these receptors.3 The delta subunit conferred slow desensitization to GABA, with rate constants of 4.8 +/- 0.5 s for alpha(4)beta(3)delta and 2.5 +/- 0.2 s for alpha(4)beta(3)gamma(2). However, both P4S and THIP demonstrated similar levels of desensitization on both receptor subtypes suggesting this effect is agonist specific.4 alpha(4)beta(3)delta and alpha(4)beta(3)gamma(2) demonstrated equal sensitivity to inhibition by the cation zinc (2-3 muM IC50). However, alpha(4)beta(3)delta receptors demonstrated greater sensitivity to inhibition by lanthanum. The IC50 for GABA antagonists SR-95531 and picrotoxin, was similar for alpha(4)beta(3)delta and alpha(4)beta(3)gamma(2). Likewise, inhibition was observed on both subtypes at high and low pH.5 alpha(4)beta(3)delta receptors were insensitive to modulation by benzodiazepine ligands. In contrast Ro15-4513 and bretazenil potentiated GABA responses on alpha(4)beta(3)gamma(2) cells, and the inverse agonist DMCM showed allosteric inhibition Of alpha(4)beta(3)gamma(2) receptors.6 The efficacy of neurosteroids at alpha(4)beta(3)delta receptors was greatly enhanced over that observed at alpha(4)beta(3)gamma(2) receptors. The greatest effect was observed using THDOC with 524+/-71.6% potentiation at alpha(4)beta(3)delta and 297.9 +/- 49.7% at alpha(4)beta(3)gamma(2) receptors. Inhibition by the steroid pregnenolone sulphate however, showed no subtype selectivity. The efficacy of both pentobarbitone and propofol was slightly augmented and etomidate greatly enhanced at alpha(4)beta(3)delta receptors versus alpha(4)beta(3)gamma(2) receptors.7 We show that the alpha(4)beta(3)delta receptor has a distinct pharmacology and kinetic profile. With its restricted distribution within the brain and unique pharmacology this receptor may play an important role in the action of neurosteroids and anaesthetics.