Glycine binding site of the synaptic NMDA receptor in subpostremal NTS neurons
Glycine binding site of the synaptic NMDA receptor in subpostremal NTS neurons
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DOI：
10.1152/jn.00927.2004
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发表时间：
2005-07-01
影响因子：
2.5
通讯作者：
Varanda, WA
中科院分区：
文献类型：
--
作者：
Baptista, V;Varanda, WA
孤束核（NTS）在多种自主神经反射功能的控制中起重要作用，并含有谷氨酸和GABA作为主要的神经递质。在这项工作中，我们使用膜片钳记录在横向切片制备从大鼠研究是否饱和或不饱和的N-甲基-D-天冬氨酸（NMDA）受体的甘氨酸结合位点的subpostremal NTS的神经元。除了在超极化电压和接近逆转电位，甘氨酸增强NMDA反应的浓度依赖性方式。甘氨酸增强了由谷氨酸能电流转移的总电荷（500 μ M;在+50 mV时从28 +/-13 pC到42 +/-18 pC，n = 7，P < 0.05）。甘氨酸增加突触后膜的电导，而不改变其逆转电位，无论是在存在（从2.4 +/- 0.06至3.4 +/- 0.09 nS; n = 7）和缺乏（从3.1 +/- 0.06至4.4 +/- 0.10 nS; n = 8）的浴溶液中的Mg 2+。在士的宁存在的情况下，D-丝氨酸也增加了NMDA成分的幅度（68 +/-19%，P < 0.05，n = 5）。膜电位被甘氨酸超极化（16 +/- 6 mV，n = 8），表明存在抑制性甘氨酸能受体。我们的研究结果表明，在subpostremal NTS的神经元中的NMDA受体的甘氨酸网站是不饱和的，甘氨酸可能作为一个调制器的NMDA传输在这个核。
The nucleus of the tractus solitarius (NTS) plays an important role in the control of several autonomic reflex functions and has glutamate and GABA as main neurotransmitters. In this work, we used patch-clamp recordings in transverse slice preparations from rats to study whether the glycine binding site of the N-methyl-D-aspartate (NMDA) receptor is saturated or not in neurons of the subpostremal NTS. Except at hyperpolarized voltages and close to the reversal potential, glycine potentiated the NMDA responses in a concentration-dependent manner. The total charge transferred by glutamatergic currents was enhanced by glycine (500 mu M; from 28 +/- 13 to 42 +/- 18 pC at +50 mV, n = 7, P < 0.05). Glycine increased the conductance of the postsynaptic membrane, without altering its reversal potential, both in the presence (from 2.4 +/- 0.06 to 3.4 +/- 0.09 nS; n = 7) and absence (from 3.1 +/- 0.06 to 4.4 +/- 0.10 nS; n = 8) of Mg2+ in the bathing solution. D-serine, in the presence of strychnine, also increased the amplitude of the NMDA component (by 68 +/- 19%, P < 0.05, n = 5). The membrane potential was hyperpolarized (16 +/- 6 mV, n = 8) by glycine, suggesting the presence of inhibitory glycinergic receptors. Our results indicate that the glycine site of the NMDA receptor in neurons of the subpostremal NTS is not saturated and that glycine may act as a modulator of the NMDA transmission in this nucleus.