GABAergic currents in RT and VB thalamic nuclei follow kinetic pattern of alpha3- and alpha1-subunit-containing GABAA receptors.
GABAergic currents in RT and VB thalamic nuclei follow kinetic pattern of alpha3- and alpha1-subunit-containing GABAA receptors.
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DOI：
10.1111/j.1460-9568.2007.05693.x
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发表时间：
2007-08
期刊：
影响因子：
--
通讯作者：
Vicini S
中科院分区：
文献类型：
--
作者：
Mozrzymas JW;Barberis A;Vicini S
丘脑网状 (RT) 核的抑制性突触后电流 (IPSC) 比邻近的腹基底 (VB) 神经元慢得多。有人提出，含有α3亚基的受体是RT神经元中缓慢的IPSC的基础，而VB核中的快速突触电流是由于γ-氨基丁酸A受体（GABAAR）（包括α1亚基）造成的。在我们最近的研究中[Barberis 等人。 (2007) 欧元。 J. Neurosci., 25, 2726–2740]我们发现α3β2γ2和α1β2γ3受体介导的电流动力学存在显着差异，这是由于不同的结合和脱敏特性造成的。然而，尚未对来自 RT 和 VB 神经元的神经元 GABAAR 的动力学与含 α3 和 α1 亚基的受体进行直接比较。为此，从 VB 和 RT 区域神经元切除的斑块中记录了当前对超快 GABA 应用的反应。 RT 和 VB 神经元的失活动力学与 α3β2γ2 和 α1β2γ2 受体介导的电流非常相似。在 RT 神经元中，非饱和 [GABA] 引发的电流起始速度非常缓慢，这是含有 α3 亚基的受体的标志。在 VB 和 RT 神经元中，短暂 GABA 脉冲引起的单通道电流与 α1β2γ2 和 α3β2γ2 受体具有相似的特征。然而，在静止条件下，神经元和各自重组受体的单通道电流之间的相似性不太明显。我们提出，VB 和 RT 核中 GABA 能电流的非平稳动力学模拟了由 α1 和 α3 亚基受体介导的电流。神经元和重组受体的静态动力学之间的差异可能反映了 GABAAR 介导这些神经元中的相位电流和强直电流之间的差异。
Inhibitory postsynaptic currents (IPSCs) of the thalamic reticular (RT) nucleus are dramatically slower than in the neighboring ventrobasal (VB) neurons. It has been suggested that α3-subunit-containing receptors underlie slow IPSCs in RT neurons, while rapid synaptic currents in the VB nucleus are due to γ-aminobutyric acid A receptors (GABAARs), including the α1-subunit. In our recent study [Barberis et al. (2007) Eur. J. Neurosci., 25, 2726–2740] we have found that profound differences in kinetics of currents mediated by α3β2γ2 and α1β2γ3 receptors resulted from distinct binding and desensitization properties. However, a direct comparison between kinetics of neuronal GABAARs from RT and VB neurons and α3- and α1-subunit-containing receptors has not been made. For this purpose, current responses to ultrafast GABA applications were recorded from patches excised from neurons in VB and RT areas. Deactivation kinetics determined for RT and VB neurons closely resembled that in currents mediated by α3β2γ2 and α1β2γ2 receptors. In RT neurons, currents elicited by non-saturating [GABA] had a remarkably slow onset, a hallmark of α3-subunit-containing receptors. In VB and RT neurons, single-channel currents elicited by brief GABA pulses had similar characteristics to those of α1β2γ2 and α3β2γ2 receptors. However, in stationary conditions, similarity between single-channel currents in neurons and respective recombinant receptors was less apparent. We propose that the non-stationary kinetics of GABAergic currents in VB and RT nuclei mimic that of currents mediated by α1- and α3-subunit-containing receptors. The dissimilarity between stationary kinetics of neuronal and recombinant receptors probably reflects differences between GABAARs mediating phasic and tonic currents in these neurons.
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