Ionotropic glutamate receptors contribute to maintained neuronal hyperexcitability following spinal cord injury in rats.
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 microg) significantly attenuated the activity of WDR, but not LT and HT neurons; whereas, NBQX (AMPA receptor antagonist, 0.5 and 1 microg) significantly attenuated neuronal activity in all three phenotypes of neurons (*p<0.05). However, MCPG (group I/II metabotropic glutamate receptor antagonist, 100 microg) 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.
Leem
Joong Woo
JW
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. jwleem@yumc.yonsei.ac.kr
Kim
Hee Kee
HK
Hulsebosch
Claire E
CE
Gwak
Young Seob
YS
D000200:Action Potentials / Q000187:drug effects / Q000502:physiology; D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D008297:Male; D010812:Physical Stimulation; D020671:Posterior Horn Cells / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013904:Thoracic Vertebrae
D018691:Excitatory Amino Acid Antagonists; D018091:Receptors, AMPA; D016194:Receptors, N-Methyl-D-Aspartate; D016291:Dizocilpine Maleate