Peripheral NMDA and non-NMDA receptors contribute to nociception: an electrophysiological study.
The present study investigated the effects of peripheral administration of N-methy-D-aspartate (NMDA) and non-NMDA receptor antagonists on C-fiber evoked responses of the spinal dorsal horn neurons in the spinalized rats. When DL-2-amino-5-phosphonovaleric acid (AP5) (10 mM, 1 mM, 0.1 mM, 20 microl) or 6, 7-dinitroquinoxaline-2, 3-dione (DNQX) (1 mM, 0.1 mM, 0.01 mM, 20 microl) was subcutaneously injected into the receptive field on the hindplantar region, C-fiber evoked responses of the dorsal horn neurons were profoundly inhibited in a dose-dependent manner. Three hours after subcutaneous injection of carrageenan into the ipsilateral hindpaw, NMDA and non-NMDA antagonist-induced inhibition of C-fiber evoked responses was more potent than that in the normal rat (Student's t-test, p < 0.05). In the carragenan-treated rats, DNQX-induced inhibition was stronger than AP-5-induced one (Student's t-test, p < 0.05). The results suggest that peripheral NMDA and non-NMDA receptors are involved in mediating excitation of nociceptors.
Wang
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C
Key Laboratory of Neurobiology, Institute of Shanghai Physiology, Chinese Academy of Science, Shanghai, China.
Wang
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Y
Zhao
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Z
D015763:2-Amino-5-phosphonovalerate / Q000494:pharmacology; D000818:Animals; D002351:Carrageenan / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004594:Electrophysiology; D005071:Evoked Potentials / Q000187:drug effects; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D006614:Hindlimb; D007279:Injections, Subcutaneous; D008297:Male; D009412:Nerve Fibers / Q000187:drug effects / Q000502:physiology; D009619:Nociceptors / Q000502:physiology*; D011810:Quinoxalines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D017459:Receptors, Amino Acid / Q000502:physiology*; D016194:Receptors, N-Methyl-D-Aspartate / Q000502:physiology*; D012016:Reference Values
D018691:Excitatory Amino Acid Antagonists; D011810:Quinoxalines; D017459:Receptors, Amino Acid; D016194:Receptors, N-Methyl-D-Aspartate; C056723:FG 9041; D015763:2-Amino-5-phosphonovalerate; D002351:Carrageenan