Zhou Q Q, Imbe H, Zou S, Dubner R, Ren K
Department of Oral and Craniofacial Biological Sciences, University of Maryland Dental School, Baltimore, MD 21201-1586, USA.
Brain Res Mol Brain Res. 2001 Mar 31;88(1-2):186-93. doi: 10.1016/s0169-328x(01)00041-9.
Glutamate receptors are involved in spinal nociceptive transmission and the development of persistent inflammatory hyperalgesia. It is unclear, however, whether there are changes in glutamate receptor gene expression associated with tissue injury. In the present study, we used reverse transcription-polymerase chain reaction (RT-PCR) to examine the modulation of alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor gene expression in the rat spinal cord by inflammation. Inflammation was introduced into the hindpaw by intraplantar injection of 0.2 ml of complete Freund's adjuvant (CFA). At 2 h-14 d after inflammation, total RNAs from L4,5 spinal cord were used for RT-PCR with primers targeted at eight flip-flop splice variants of the AMPA receptor subunits. It was found that the GluR1-flop mRNA was up-regulated at 2 h-5 h (P<0.05), down-regulated at 3 d (P=0.05), and returned to control levels at 7 d following inflammation. The GluR2-flip and GluR3-flop mRNAs were up-regulated at 5 h-1 d (P<0.05) and returned to control levels at 3 d after inflammation. The GluR1-flip mRNA was not detected in the samples and the mRNAs for other splice variants did not exhibit significant changes. Immunocytochemical analysis of GluR1 and GluR2 subunits indicate that the protein translation products of these subunits were also increased in the spinal cord. These results demonstrate an increased expression of AMPA receptor subunits that correlates with the acute phase of CFA-induced inflammation and hyperalgesia. Selective changes in the expression of the flip-flop splice variants of the AMPA receptor suggest a reorganization of the composition of the AMPA receptor complex and its involvement in the development of inflammatory hyperalgesia.
谷氨酸受体参与脊髓伤害性感受传递以及持续性炎症性痛觉过敏的形成。然而，尚不清楚与组织损伤相关的谷氨酸受体基因表达是否存在变化。在本研究中，我们采用逆转录聚合酶链反应（RT-PCR）来检测炎症对大鼠脊髓中α-氨基-3-羟基-5-甲基-4-异恶唑丙酸（AMPA）受体基因表达的调节作用。通过足底内注射0.2 ml完全弗氏佐剂（CFA）将炎症引入后爪。在炎症发生后的2小时至14天，取L4、5脊髓的总RNA，使用针对AMPA受体亚基的8种翻转剪接变体的引物进行RT-PCR。结果发现，GluR1-flop mRNA在炎症后2小时至5小时上调（P<0.05），在3天时下调（P=0.05），并在7天时恢复至对照水平。GluR2-flip和GluR3-flop mRNA在5小时至1天时上调（P<0.05），并在炎症后3天恢复至对照水平。样本中未检测到GluR1-flip mRNA，其他剪接变体的mRNA也未表现出显著变化。对GluR1和GluR2亚基的免疫细胞化学分析表明，这些亚基的蛋白质翻译产物在脊髓中也增加。这些结果表明，AMPA受体亚基的表达增加与CFA诱导的炎症和痛觉过敏的急性期相关。AMPA受体翻转剪接变体表达的选择性变化表明AMPA受体复合物的组成发生了重组，并且其参与了炎症性痛觉过敏的形成。
