Abstract
Nitric oxide plays an important role in spinal nociception. The present study explored the effects of nitric oxide on the spinal long-term potentiation associated with nociception. (1) Nitric oxide synthase inhibitor L-NAME (1 mM, 20 microl) and the nitric oxide scavenger hemoglobin (2 mg/ml, 20 mul) strikingly blocked the induction of tetanic sciatic stimulation-induced spinal long-term potentiation of C-fiber-evoked field potentials. L-arginine, a substrate of nitric oxide synthase, completely reversed L-NAME-induced inhibition. However, D-NAME (1 mM, 20 microl), an inactive form of L-NAME, had little effect on the spinal LTP. (2) The same tetanic sciatic stimulation induced long-term thermal hyperalgesia, which was blocked by pre-application of L-NAME. These results suggest the involvement of nitric oxide in the spinal long-term potentiation of C-fiber-evoked field potentials and related behavior changes.
Publication types
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Comparative Study
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Research Support, Non-U.S. Gov't
MeSH terms
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Analysis of Variance
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Animals
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Arginine / pharmacology
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Drug Interactions
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Enzyme Inhibitors / pharmacology
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Evoked Potentials / physiology
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Evoked Potentials / radiation effects
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Functional Laterality
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Hemoglobins / pharmacology
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Hyperalgesia / physiopathology
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Long-Term Potentiation / drug effects
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Long-Term Potentiation / physiology*
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Long-Term Potentiation / radiation effects
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Male
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NG-Nitroarginine Methyl Ester / pharmacology
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Nerve Fibers, Unmyelinated / physiology
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Nerve Fibers, Unmyelinated / radiation effects
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Nitric Oxide Synthase / metabolism*
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Nociceptors / physiology*
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Pain Measurement / methods
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Rats
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Rats, Sprague-Dawley
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Reaction Time / physiology
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Reaction Time / radiation effects
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Sciatic Nerve / physiology
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Sciatic Nerve / radiation effects
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Spinal Cord / drug effects
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Spinal Cord / enzymology*
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Spinal Cord / physiopathology*
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Time Factors
Substances
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Enzyme Inhibitors
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Hemoglobins
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Arginine
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Nitric Oxide Synthase
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NG-Nitroarginine Methyl Ester