Ionotropic glutamate receptors contribute to maintained neuronal hyperexcitability following spinal cord injury in rats |
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Authors: | Joong Woo Leem Hee Kee Kim Claire E. Hulsebosch Young Seob Gwak |
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Affiliation: | a Department of Physiology, Brain Research Institute, and BK21 Project for Medical Science, Yonsei University College of Medicine, C.P.O. Box 8044, Seoul, 120-752, Republic of Korea b Department of Neuroscience and Cell Biology, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1043, USA c Department of Anesthesiology, Perioperative Medicine and Pain Management, University of Miami Miller School of Medicine, University of Miami, 1011 NW 15th ST, Miami, FL 33136, USA |
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Abstract: | In this study, we examined whether topical treatment of glutamate receptor antagonists attenuate hyperexcitability of lumbar spinal dorsal horn neurons following low thoracic hemisection spinal cord injury in rats. Four weeks after spinal hemisection, neuronal activity in response to mechanical stimuli applied on the peripheral receptive field was significantly increased in three different phenotypes of lumbar spinal dorsal horn neurons: wide dynamic range (WDR), low threshold (LT) and high threshold (HT). Topical application of MK-801 (NMDA receptor antagonist, 50 µg) significantly attenuated the activity of WDR, but not LT and HT neurons; whereas, NBQX (AMPA receptor antagonist, 0.5 and 1 µg) significantly attenuated neuronal activity in all three phenotypes of neurons (*p < 0.05). However, MCPG (group I/II metabotropic glutamate receptor antagonist, 100 µg) had no effect. The present study, in the context of previous work, suggests that ionotropic glutamate receptor activation play critical roles in the maintenance of neuronal hyperexcitability and neuropathic “below-level” pain behavior following spinal hemisection injury. |
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Keywords: | Central neuropathic pain Hyperexcitability NBQX MCPG MK-801 Spinal cord injury |
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