Bukanova Julia V, Kondratenko Rodion V, Solntseva Elena I
Research Center of Neurology, Moscow, Russia.
Cell Biochem Biophys. 2025 Jun;83(2):2453-2459. doi: 10.1007/s12013-024-01654-6. Epub 2024 Dec 28.
Allopregnanolone (Allo) is a positive allosteric modulator of the GABA receptor, and amiloride (Ami) is a competitive antagonist of the GABA receptor. The purpose of this work was to study the combined effect of Allo and Ami on functional activity of GABA receptor. The GABA-induced chloride current (I) was measured in isolated Purkinje cells of rat cerebellum using the patch-clamp technique and a system of fast application. Our results indicate that Allo suppresses the inhibitory effect of Ami on I, the IC value of Ami concentration-response curve was increased from 164 to 547 µM (P < 0.001) in the presence of Allo. Next, GABA concentration-response curves (EC = 5.8 µM) were constructed in the presence of Allo (EC = 1.2 µM), Ami (EC = 25.5 µM), and the combination of Allo+Ami (EC = 3.2 µM). Changes in EC values as a percentage relative to the control were calculated. The blocking effect of Ami is reduced in the presence of Allo (340% vs 150%, P < 0.01) and the potentiating effect of Allo does not change in the presence of Ami (78% vs 87%, P > 0.05). The results suggest that there is an allosteric relationship between the Allo and Ami binding sites on GABA receptor that operates in one direction, from Allo sites to Ami site, but not vice versa.
别孕烯醇酮（Allo）是GABA受体的正变构调节剂，而阿米洛利（Ami）是GABA受体的竞争性拮抗剂。这项工作的目的是研究Allo和Ami对GABA受体功能活性的联合作用。使用膜片钳技术和快速施加系统，在大鼠小脑的离体浦肯野细胞中测量GABA诱导的氯离子电流（I）。我们的结果表明，Allo抑制了Ami对I的抑制作用，在存在Allo的情况下，Ami浓度 - 反应曲线的IC值从164增加到547μM（P <0.001）。接下来，在存在Allo（EC = 1.2μM）、Ami（EC = 25.5μM）以及Allo + Ami组合（EC = 3.2μM）的情况下构建GABA浓度 - 反应曲线（EC = 5.8μM）。计算相对于对照的EC值变化百分比。在存在Allo的情况下，Ami的阻断作用降低（340%对150%，P <0.01），并且在存在Ami的情况下，Allo的增强作用没有变化（78%对87%，P> 0.05）。结果表明，GABA受体上的Allo和Ami结合位点之间存在变构关系，其作用方向是单向的，从Allo位点到Ami位点，反之则不然。
