Role of glial and neuronal glycine transporters in the control of glycinergic and glutamatergic synaptic transmission in lamina X of the rat spinal cord
Role of glial and neuronal glycine transporters in the control of glycinergic and glutamatergic synaptic transmission in lamina X of the rat spinal cord
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DOI：
10.1113/jphysiol.2004.068858
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发表时间：
2004-08-15
影响因子：
5.5
通讯作者：
Trouslard, J
中科院分区：
文献类型：
--
作者：
Bradaïa, A;Schlichter, R;Trouslard, J
采用大鼠脊髓薄片X层神经元全细胞电压钳记录技术，研究了甘氨酸转运体（GlyT）拮抗剂对甘氨酸能抑制性突触后电流（IPSC）和谷氨酸能兴奋性突触后电流（EPSC）的影响。我们使用ORG 24598和ORG 25543，分别是神经胶质GlyT（GlyT 1）和神经元GlyT（GlyT 2）的选择性拮抗剂：在大鼠（P12-P16）中，在犬尿烯酸、6-氰基-7-硝基喹喔啉-2，3-二酮（CNQX）和荷包牡丹碱存在下，ORG 24598和ORG 25543以10 μ M的浓度单独应用，在-60 mV下诱导-10/-50 pA的平均内向电流，并显著增加微型（mIPSC）的衰减时间常数，自发性（sIPSC）和电诱发的甘氨酸能（eIPSC）抑制性突触后电流。ORG 25543而非ORG 24598降低了mIPSC和sIPSC的频率。用N-甲基-D-葡糖胺代替细胞外钠或用微摩尔浓度的甘氨酸灌注切片也增加了甘氨酸能IPSC的衰减时间常数。相比之下，在士的宁存在下记录的微型GABA能IPSC的衰减时间常数、振幅和频率不受ORG 24598和ORG 25543的影响。在士的宁、荷包牡丹碱和CNQX的存在下，我们记录了电诱发的NMDA受体介导的EPSCs（eEPSCs）。eEPSC被30 μ M D-2-氨基-5-膦酰基戊酸（APV）（一种NMDA受体的拮抗剂）和30 μ M二氯犬尿烯酸（DCKA）（一种NMDA受体甘氨酸位点的拮抗剂）抑制。甘氨酸（1-5 μ M）和D-丝氨酸（10 μ M）增加eEPSC的幅度，而L-丝氨酸没有影响。ORG 24598和ORG 25543显著增加NMDA受体介导的eEPSC的振幅，而不影响非NMDA受体介导的eEPSC的振幅。我们的结论是，阻断神经胶质细胞和/或神经元甘氨酸转运蛋白增加了脊髓切片中的甘氨酸水平，这反过来又延长了甘氨酸能突触电流的持续时间，并增强了NMDA介导的突触反应。
Using whole cell voltage clamp recordings from lamina X neurones in rat spinal cord slices, we investigated the effect of glycine transporter (GlyT) antagonists on both glycinergic inhibitory postsynaptic current (IPSCs) and glutamatergic excitatory postsynaptic current (EPSCs). We used ORG 24598 and ORG 25543, selective antagonists of the glial GlyT (GlyT1) and neuronal GlyT (GlyT2), respectively: In rats (P12-P16) and in the presence of kynurenic acid, 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX) and bicuculline, ORG 24598 and ORG 25543 applied individually at a concentration of 10 muM induced a mean inward current of -10/-50 pA at -60 mV and increased significantly the decay time constants of miniature (mIPSCs), spontaneous (sIPSCs) and electrically evoked glycinergic (eIPSCs) inhibitory postsynaptic currents. ORG 25543, but not ORG 24598, decreased the frequency of mIPSCs and sIPSCs. Replacing extracellular sodium with N-methyl-D-glucamine or superfusing the slice with micromolar concentrations of glycine also increased the decay time constant of glycinergic IPSCs. By contrast, the decay time constant, amplitude and frequency of miniature GABAergic IPSCs recorded in the presence of strychnine were not affected by ORG 24598 and ORG 25543. In the presence of strychnine, bicuculline and CNQX, we recorded electrically evoked NMDA receptor-mediated EPSCs (eEPSCs). eEPSCs were suppressed by 30 muM D-2-amino-5-phosphonovalerate (APV), an antagonist of the NMDA receptor, and by 30 muM dichlorokynurenic acid (DCKA), an antagonist of the glycine site of the NMDA receptor. Glycine (1-5 muM) and D-serine (10 muM) increased the amplitude of eEPSCs whereas L-serine had no effect. ORG 24598 and ORG 25543 increased significantly the amplitude of NMDA receptor-mediated eEPSCs without affecting the amplitude of non-NMDA receptor-mediated eEPSCs. We conclude that blocking glial and/or neuronal glycine transporters increased the level of glycine in spinal cord slices, which in turn prolonged the duration of glycinergic synaptic current and potentiated the NMDA-mediated synaptic response.