J Korean Pain Soc.  2000 Jun;13(1):19-30.

Effects of NO Synthase Inhibitor on Responsiveness of Dorsal Horn Neurons in Neuropathic Pain Animal Model

• Leem JW
• Gwak YS
• Chung SS
• Lee KR
• Yoon DM
• Nam TS

Abstract

BACKGROUND: Partial nerve injury to a peripheral nerve may induce the development of neuropathic pain which is characterized by symptams such as spontaneous burning pain, allodynia and hyperalgesia. Though underlying mechanism has not fully understood, sensitization of dorsal horn neurons may con- tribute to generate such symptoms. Nitric oxide acts as an inter- and intracellular messenger in the nervous system and is produced from L-arginine by nitric oxide synthase (NOS). Evidence is accumulating which indicate that nitric oxide may mediate nociceptive information trsnsmission. Recently, it has been reported that NOS inhibitor suppresses neuropathic pain behavior in an neuropathic pain animal model. This study was conducted to determine whether nitric oxide could be involved in the sensitization of dorsal horn neurons in neuropathic animal model.
METHODS
Neuropathic animal model was made by tightly ligating the left L5 and L6 spinal nerves and we examined the effects of iontophoretically applied NOS inhibitot (L-NAME) on the dorsal horn neurons responses to mechanical stimuli within the receptive fields.
RESULTS
In normal animals, NOS inhibitor (L-NAME) specifically suppressed the responses to the noxious mechanical stimuli. In neuropathic animals, the dorsal horn neuron's responses to mechanical stimuli were enhanced and NOS inhibitor suppressed the dorsal horn neurons enhanced responses to non-noxious stimuli as well as those to noxious ones.
CONCLUSIONS
These results suggest that nitric oxide may mediate nociceptive transmission in normal animal and also mediate sensitization of dorsal horn neurons in neuropathic pain state.

Keyword

Iontophoresis; L-NAME; Neuropathic; Nitric oxide

MeSH Terms

Animals*
Arginine
Burns
Horns
Hyperalgesia
Iontophoresis
Models, Animal*
Nervous System
Neuralgia*
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitric Oxide Synthase*
Peripheral Nerves
Posterior Horn Cells*
Spinal Nerves
Arginine
NG-Nitroarginine Methyl Ester
Nitric Oxide
Nitric Oxide Synthase