Nitrous oxide and the inhibitory synaptic transmission in rat dorsal horn neurons
Nitrous oxide and the inhibitory synaptic transmission in rat dorsal horn neurons
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DOI：
10.1016/j.ejpain.2009.01.008
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发表时间：
2010-01-01
影响因子：
3.6
通讯作者：
Kohno, Tatsuro
中科院分区：
文献类型：
--
作者：
Georgiev, Stefan K.;Baba, Hiroshi;Kohno, Tatsuro
一氧化二氮（N2O）的镇痛作用被认为依赖于下行抑制神经元激活后脊髓中去甲肾上腺素的释放。除了这种对脊髓抑制的间接促进外，我们之前还发现N2O直接抑制背角神经元中的谷氨酸受体。由于全麻可能影响突触传递的兴奋性和/或抑制性成分，我们试图评估N2O对脊髓神经元抑制性传递的直接影响。利用全细胞膜片钳记录大鼠脊髓横断切片，我们研究了50% N2O和0.5%异氟醚（均为0.3大鼠最低肺泡浓度）对外源性γ -氨基丁酸（GABA）和甘氨酸诱导的大鼠背角II层神经元电流的作用。GABA-和甘氨酸诱导电流的振幅和集成面积不受N2O的显著影响，但在异氟醚的存在下有所增加。N2O不影响GABA或甘氨酸受体介质红色微型突触后电流的振幅、频率和衰减时间概率分布。我们进一步试图确定N2O对GABA和甘氨酸受体介导的局灶刺激诱发的突触电流的影响，并发现大多数神经元没有影响。这些和其他研究结果表明，N2O在脊髓中具有独立的作用，不同于挥发性麻醉剂的作用，包括通过对嗜离子性谷氨酸能受体的作用抑制SG神经元的兴奋，以及通过降去甲肾上腺素能系统增强抑制。(C) 2009年欧洲国际疼痛研究协会联合会分会。Elsevier Ltd.出版。版权所有。
The analgesic effect of nitrous oxide (N2O) is thought to depend on noradrenaline release in the spinal cord following activation of descending inhibitory neurons. In addition to this indirect facilitation of inhibition in the spinal cord, we previously showed direct inhibition of glutamate receptors in dorsal horn neurons by N2O. Since general anesthetics could possibly affect excitatory and/or inhibitory components of synaptic transmission, we sought to evaluate the direct effect of N2O on inhibitory transmission in spinal cord neurons.Using whole-cell patch-clamp recording from rat transversal spinal cord slices, we investigated the actions of 50% N2O and 0.5% isoflurane (both 0.3 rat MAC: minimum alveolar concentration) on exogenously applied gamma-aminobutyric acid (GABA)- and glycine-induced currents in rat dorsal horn lamina II neurons. The amplitudes and integrated areas of GABA- and glycine-induced currents were not significantly affected by N2O, but were increased in the presence of isoflurane. N2O did not affect the amplitude, frequency or decay time probability distribution of either GABA or glycine receptor-media red miniature postsynaptic currents. We further sought to determine the effect of N2O On focal stimulation-evoked synaptic Currents mediated by GABA and glycine receptors, and found no effect in the majority of neurons.These and other findings suggest that N2O has a discrete action in the spinal cord, distinct from the effects of the volatile anesthetics, consisting of inhibition of excitation in SG neurons through an action on ionotropic glutamatergic receptors and potentiation of inhibition through the descending noradrenergic system. (C) 2009 European Federation of International Association for the Study of Pain Chapters. Published by Elsevier Ltd. All rights reserved.