Effect of inhibition of spinal cord glutamate transporters on inflammatory pain induced by formalin and complete Freund's adjuvant.
Effect of inhibition of spinal cord glutamate transporters on inflammatory pain induced by formalin and complete Freund's adjuvant.
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DOI：
10.1097/aln.0b013e318205df50
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发表时间：
2011-02
期刊：
影响因子：
8.8
通讯作者：
Tao YX
中科院分区：
文献类型：
--
作者：
Yaster M;Guan X;Petralia RS;Rothstein JD;Lu W;Tao YX
脊髓谷氨酸转运体清除突触释放的谷氨酸并维持正常的感觉传递。然而，它们的超微结构定位是未知的。此外，它们是否以及如何参与炎性疼痛尚未仔细研究。采用电子显微镜进行免疫金标记，以表征背角浅层谷氨酸转运蛋白的突触和非突触定位。它们的表达和摄取活性福尔马林和完全弗氏佐剂（CFA）诱导的炎症后进行了评估，通过蛋白质印迹和谷氨酸摄取测定。研究鞘内注射谷氨酸转运蛋白激活剂[（R）-（−）-5-甲基-1-烟酰基-2-吡唑啉]、抑制剂[DL-苏型-β-苄氧基天冬氨酸（TBOA）、二氢红藻氨酸盐和DL-苏型-β-羟基天冬氨酸]或TBOA加III组代谢型谷氨酸受体拮抗剂[（RS）-α-甲基丝氨酸-O-磷酸盐]对福尔马林和CFA诱导的炎性疼痛的影响。在浅层背角，兴奋性氨基酸载体1位于突触前膜，突触后膜，轴突和树突膜在非突触网站，而谷氨酸转运蛋白-1和谷氨酸/天冬氨酸转运蛋白是突出的胶质细胞膜。虽然这三种脊髓谷氨酸转运蛋白的表达在福尔马林注射后1小时或CFA注射后6小时没有改变，但谷氨酸摄取活性在这些时间点降低。鞘内注射（R）-（−）-5-甲基-1-烟酰基-2-吡唑啉对福尔马林诱导的疼痛行为没有影响。相比之下，鞘内TBOA，二氢红藻氨酸，DL-苏-β-羟基天冬氨酸减少福尔马林诱发的疼痛行为在第二阶段。鞘内注射TBOA也减弱CFA诱导的热痛敏后6小时CFA注射。TBOA的镇痛作用可被（RS）-α-甲基丝氨酸-O-磷酸盐阻断。我们的研究结果表明，脊髓谷氨酸转运体抑制通过激活抑制性突触前III组代谢型谷氨酸受体来缓解炎症性疼痛。
Spinal cord glutamate transporters clear synaptically released glutamate and maintain normal sensory transmission. However, their ultrastructural localization is unknown. Moreover, whether and how they participate in inflammatory pain has not been carefully studied. Immunogold labeling with electron microscopy was carried out to characterize synaptic and non-synaptic localization of glutamate transporters in the superficial dorsal horn. Their expression and uptake activity after formalin- and complete Freund’s adjuvant (CFA)-induced inflammation were evaluated by Western blot and glutamate uptake assays. Effects of intrathecal glutamate transporter activator [(R)-(−)-5-methyl-1-nicotinoyl-2-pyrazoline], inhibitors [DL-threo-β-benzyloxyaspartate (TBOA), dihydrokainate, and DL-threo-beta-hydroxyaspartate], or TBOA plus a group III metabotropic glutamate receptor antagonist [(RS)-α-methylserine-O-phosphate] on formalin- and CFA-induced inflammatory pain were examined. In the superficial dorsal horn, excitatory amino acid carrier 1 is localized in pre-synaptic membrane, postsynaptic membrane, and axonal and dendritic membranes at non-synaptic sites, whereas glutamate transporter-1 and glutamate/aspartate transporter are prominent in glial membranes. Although expression of these three spinal glutamate transporters was not altered at 1 h after formalin injection or 6 h after CFA injection, glutamate uptake activity was decreased at these time points. Intrathecal (R)-(−)-5-methyl-1-nicotinoyl-2-pyrazoline had no effect on formalin-induced pain behaviors. In contrast, intrathecal TBOA, dihydrokainate, and DL-threo-beta-hydroxyaspartate reduced formalin-evoked pain behaviors in the second phase. Intrathecal TBOA also attenuated the CFA-induced thermal hyperalgesia at 6 h after CFA injection. The antinociceptive effects of TBOA were blocked by coadministration of (RS)-α-methylserine-O-phosphate. Our findings suggest that spinal glutamate transporter inhibition relieves inflammatory pain through activation of inhibitory pre-synaptic group III metabotropic glutamate receptors.