Acting locally but sensing globally: impact of GABAergic synaptic plasticity on phasic and tonic inhibition in the thalamus
Acting locally but sensing globally: impact of GABAergic synaptic plasticity on phasic and tonic inhibition in the thalamus
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DOI：
10.1113/jphysiol.2008.158576
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发表时间：
2008-11-01
影响因子：
5.5
通讯作者：
Brickley, Stephen G.
中科院分区：
文献类型：
--
作者：
Bright, Damian P.;Brickley, Stephen G.
我们已经发现，成年丘脑皮质中继神经元表现出持续增强的突触抑制触发的瞬时动作电位发射的一个单一的丘脑中继神经元。IPSC频率的持续活性依赖性增加（+48.3 +/-11.4%，n = 32）被单个细胞内的螯合钙、清除一氧化氮或阻断丘脑中的NMDA受体激活所阻断。令人惊讶的是，这些细胞中突触外GABA（A）受体激活导致的紧张性抑制不受这种局部可塑性的影响。然而，在整个丘脑的GABA释放发生广泛变化后，强直性抑制增加（+131.9 +/-56.5%，n = 13）。这些数据表明，需要膜超极化的丘脑皮质睡眠状态振荡将受到通过突触外GABA（A）受体作用的GABA释放的整体感知的影响。与此相反，局部变化的GABA释放的类型观察到这种新形式的活动依赖性的可塑性将影响局部整合的感觉信息，而不改变紧张性抑制的水平。
We have discovered that adult thalamocortical relay neurones exhibit a sustained enhancement of synaptic inhibition triggered by transient action potential firing of a single thalamic relay neurone. The sustained activity-dependent increase in IPSC frequency (+48.3 +/- 11.4%, n = 32) was blocked by chelating calcium inside an individual cell, by scavenging nitric oxide or by blocking NMDA receptor activation in the thalamus. Surprisingly, the tonic inhibition that is known to result from extrasynaptic GABA(A) receptor activation in these cells was unaffected by this local form of plasticity. However, tonic inhibition was increased (+131.9 +/- 56.5%, n = 13) following widespread changes in GABA release across the thalamus. These data suggest that thalamocortical sleep-state oscillations requiring membrane hyperpolarization will be influenced by global sensing of GABA release acting through extrasynaptic GABA(A) receptors. In contrast, local changes in GABA release of the type observed following this novel form of activity-dependent plasticity will influence local integration of sensory information without changing levels of tonic inhibition.