M channels containing KCNQ2 subunits modulate norepinephrine, aspartate, and GABA release from hippocampal nerve terminals
M channels containing KCNQ2 subunits modulate norepinephrine, aspartate, and GABA release from hippocampal nerve terminals
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DOI：
10.1523/jneurosci.3143-03.2004
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发表时间：
2004-01-21
影响因子：
5.3
通讯作者：
Taglialatela, M
中科院分区：
文献类型：
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作者：
Martire, M;Castaldo, P;Taglialatela, M
KCNQ 亚基编码 M 电流 (I-KM)，这是一种神经元特异性电压依赖性 K+ 电流，在控制神经元兴奋性方面具有明确的作用。在本研究中，通过综合生化、药理学和电生理学方法，评估了突触前 IKM 在从海马神经末梢（突触体）释放先前吸收的氚化去甲肾上腺素 (NE)、GABA 和 D-天冬氨酸 (D-ASP) 中的作用。 Retigabine (RT) (0.01-30 muM) 是一种 IKM 特异性激活剂，可抑制 9 mM 细胞外 K+ ([K+](e)) 引起的 [H-3]NE、[H-3]D-ASP 和 [H-3]GABA 释放。 RT 诱导的 [H-3]NE 释放抑制可通过针对 KCNQ2 亚基的多克隆抗体的突触体捕获来阻止，该效应可通过 KCNQ2 免疫肽预吸收抗体而消除；针对 KCNQ3 亚基的抗体无效。氟吡汀 (FP) 是 RT 的结构类似物，也抑制 9 mM [K+](e) 诱导的 [H-3]NE 释放，尽管其最大抑制低于 RT。在 KCNQ2 转染的中国仓鼠卵巢细胞中进行的电生理学研究表明，RT 和 FP (10 muM) 在 KCNQ2 K+ 通道激活的电压依赖性中分别引起 -19 和 -9 mV 超极化转变。在相同的细胞中，认知增强剂 10,10-双(4-吡啶基甲基)-9(10H)-蒽酮 (XE-991) (10 muM) 阻断 KCNQ2 通道并阻止其被 RT (1-10 muM) 激活。最后，XE-991（10-100μM）和四乙铵离子（100μM）消除了RT（1μM）对[H-3]NE释放的抑制作用。这些发现为 KCNQ2 K+ 通道亚基在大鼠海马神经末梢释放神经递质中的主要调节作用提供了新的证据。
KCNQ subunits encode for the M current (I-KM), a neuron-specific voltage-dependent K+ current with a well established role in the control of neuronal excitability. In this study, by means of a combined biochemical, pharmacological, and electrophysiological approach, the role of presynaptic IKM in the release of previously taken up tritiated norepineprine (NE), GABA, and D-aspartate (D-ASP) from hippocampal nerve terminals (synaptosomes) has been evaluated. Retigabine (RT) (0.01-30 muM), a specific activator of IKM, inhibited [H-3]NE, [H-3]D-ASP, and [H-3]GABA release evoked by 9 mM extracellular K+ ([K+](e)). RT-induced inhibition of [H-3]NE release was prevented by synaptosomal entrapment of polyclonal antibodies directed against KCNQ2 subunits, an effect that was abolished by antibody preabsorption with the KCNQ2 immunizing peptide; antibodies against KCNQ3 subunits were ineffective. Flupirtine (FP), a structural analog of RT, also inhibited 9 mM [K+](e)-induced [H-3]NE release, although its maximal inhibition was lower than that of RT. Electrophysiological studies in KCNQ2-transfected Chinese hamster ovary cells revealed that RT and FP (10 muM) caused a -19 and -9 mV hyperpolarizing shift, respectively, in the voltage dependence of activation of KCNQ2 K+ channels. In the same cells, the cognition enhancer 10,10-bis(4-pyridinylmethyl)-9(10H)-anthracenone (XE-991) (10 muM) blocked KCNQ2 channels and prevented their activation by RT (1-10 muM). Finally, both XE-991 (10-100 muM) and tetraethylammonium ions (100 muM) abolished the inhibitory effect of RT (1 muM) on [H-3]NE release. These findings provide novel evidence for a major regulatory role of KCNQ2 K+ channel subunits in neurotransmitter release from rat hippocampal nerve endings.