Korean J Anesthesiol.  2002 May;42(5):677-684. 10.4097/kjae.2002.42.5.677.

Effect of Spinal Adrenergic and Cholinergic Antagonists for Antinociception of Intrathecal Gabapentin

• Yoon MH
• Chung SS
• Kim HS

• KMID: 2091695
• DOI: http://doi.org/10.4097/kjae.2002.42.5.677

Abstract

BACKGROUND: Intrathecal gabapentin is effective on nociceptive states evoked by tissue injury. In addition, gabapentin interacts synergistically with clonidine at the spinal level, suggesting that a mechanism of gabapentin may be related to spinal adrenoceptors. However, it has not been established whether this drug is associated with cholinergic receptors. The aim of this study was to examine the role of spinal adrenergic and cholinergic receptors on the antinociceptive action of intrathecal gabapentin.
METHODS
Rats were implanted with lumbar intrathecal catheters. For a nociceptive test, 50nl of 5% formalin solution was injected into the hindpaw. The effect of intrathecal gabapentin, administered 10 min before the formalin injection, was assessed. Next, antagonistic effects of intrathecal prazosin, yohimbine, atropine and mecamylamine for the action of intrathecal gabapentin were evaluated.
RESULTS
Formalin injection caused a biphasic incidence of flinching of the injected paw. Intrathecal gabapentin produced a dose-dependent suppression of only the phase 2 flinching response in the formalin test. Intrathecal atropine, but not prazosin, yohimbine nor mecamylamine, reversed the antinociception of intrathecal gabapentin.
CONCLUSIONS
The antinociceptive effect of intrathecal gabapentin on facilitated states may be mediated through the muscarinic receptor but by neither the nicotinic receptor nor the adrenergic receptor at the spinal level.

Keyword

Adrenergic receptor; cholinergic receptor; gabapentin; nociception; spinal cord

MeSH Terms

Animals
Atropine
Catheters
Cholinergic Antagonists*
Clonidine
Formaldehyde
Incidence
Mecamylamine
Nociception
Pain Measurement
Prazosin
Rats
Receptors, Adrenergic
Receptors, Cholinergic
Receptors, Muscarinic
Receptors, Nicotinic
Spinal Cord
Yohimbine
Atropine
Cholinergic Antagonists
Clonidine
Formaldehyde
Mecamylamine
Prazosin
Receptors, Adrenergic
Receptors, Cholinergic
Receptors, Muscarinic
Receptors, Nicotinic
Yohimbine