Synaptic distribution of the NR1, NR2A and NR2B subunits of the N-methyl-D-aspartate receptor in the rat lumbar spinal cord revealed with an antigen-unmasking technique
Synaptic distribution of the NR1, NR2A and NR2B subunits of the N-methyl-D-aspartate receptor in the rat lumbar spinal cord revealed with an antigen-unmasking technique
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DOI：
10.1111/j.1460-9568.2004.03798.x
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发表时间：
2004-12-01
影响因子：
3.4
通讯作者：
Todd, AJ
中科院分区：
文献类型：
--
作者：
Nagy, GG;Watanabe, M;Todd, AJ
谷氨酸是脊髓中主要的兴奋性神经递质，作用于包括N-甲基-D-天冬氨酸(NMDA)受体在内的多种受体，在突触可塑性和慢性疼痛中发挥重要作用。目前已鉴定出三个NMDA受体亚基家族：NR1、NR2(A-D)和NR3(A和B)。NMDA受体是含有至少一个NR2亚基的NR1的异构体通道。有大量证据表明，NMDA受体存在于脊髓中，但对其突触分布知之甚少。我们用胃酶处理的抗原去掩蔽法揭示了NR1、NR2A和NR2B亚基，并将它们的分布与α-氨基-3-羟基-5-甲基-4-异恶唑丙酸受体GluR2亚基的分布进行了比较，后者被认为存在于脊髓中最多的谷氨酸能突触中。胃酶治疗后，用针对这些亚基的抗体进行点状标记。虽然NR1点状分布于整个灰质，但NR2a集中在III-IV板层，NR2B集中在I-II板层。每种NMDA受体抗体标记的大多数斑点均为GluR2免疫反应阳性，提示它们存在于突触，NR1和NR2a抗体的电子显微镜证实了这一点。然而，许多GluR2免疫反应阳性的斑点不显示NMDA受体免疫反应性。在板层I-II，大多数NR2B斑点也呈NR1免疫反应阳性，在板层III-IV，NR2A/NR1也有类似的排列。这些结果表明，脊髓中的许多(但不是全部)谷氨酸能突触具有NMDA受体，并且不同区域的亚单位组成不同。
Glutamate is the main excitatory neurotransmitter in the spinal cord and acts on several types of receptor, including N-methyl-D-aspartate (NMDA) receptors, which play an important role in synaptic plasticity and chronic pain. Three families of NMDA receptor subunit have been identified: NR1, NR2 (A-D) and NR3 (A and B). NMDA receptors are heteromeric channels that contain NR1 with at least one NR2 subunit. There is extensive evidence that NMDA receptors are present in spinal cord but little is known about their synaptic distribution. We have used an antigen-unmasking method involving pepsin treatment to reveal NR1, NR2A and NR2B subunits and have compared their distribution with that of the alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptor GluR2 subunit, which is thought to be present at most glutamatergic synapses throughout the spinal cord. After pepsin treatment, punctate labelling was seen with antibodies against each of these subunits. Although NR1 puncta were present throughout the grey matter, NR2A was concentrated in laminae III-IV and NR2B in laminae I-II. The majority of puncta labelled with each NMDA receptor antibody were GluR2-immunoreactive, which suggests that they were present at synapses, and this was confirmed with electron microscopy for the NR1 and NR2A antibodies. However, many GluR2-immunoreactive puncta did not show NMDA receptor immunoreactivity. In laminae I-II, most NR2B puncta were also NR1-immunoreactive and a similar arrangement was found for NR2A/NR1 in laminae III-IV. These results suggest that many, but not all, glutamatergic synapses in the spinal cord possess NMDA receptors and that subunit composition varies in different regions.