Effect of subarachnoid gabapentin on tactile-evoked allodynia in a surgically induced neuropathic pain model in the rat

Reg Anesth. May-Jun 1997;22(3):249-56. doi: 10.1016/s1098-7339(06)80010-6.

Abstract

Background and objectives: Spinal gamma-aminobutyric acid (GABA) receptors have been shown to modulate post-nerve injury-induced allodynia. This study sought to examine the antiallodynic effects of a GABA analog gabapentin [1-(aminomethyl)cyclohexaneacetic acid], given by subarachnoid injection in a rat neuropathic pain model.

Methods: The rats were prepared with lumbar subarachnoid catheters, and allodynia was induced in rats by ligation of the L5-6 nerve roots (Chung model).

Results: Spinal injection of gabapentin resulted in a dose-dependent (10-1,000 microg) antagonism of the allodynia at doses that had no detectable effect on motor function. Subarachnoid injection of either the GABA A antagonist bicuculline (0.3 microg), or the GABA B antagonist CGP 35348 (30 microg) 5 minutes before or 60 minutes after injection of GABA receptor agonist did not reverse the antiallodynic effects produced by gabapentin.

Conclusions: Gabapentin shows antiallodynic effect, but its mechanism is not known. The failure to reverse this effect by GABA A or B antagonists at doses that reverse the effects of the respective agonists suggests that gabapentin is involved in the modulation of spinal systems by mechanisms that do not involve either a GABA A or a GABA B site.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Acetates / administration & dosage
  • Acetates / antagonists & inhibitors
  • Acetates / therapeutic use*
  • Amines*
  • Analgesics, Non-Narcotic / administration & dosage
  • Analgesics, Non-Narcotic / antagonists & inhibitors
  • Analgesics, Non-Narcotic / therapeutic use*
  • Animals
  • Behavior, Animal / drug effects
  • Catheterization
  • Cyclohexanecarboxylic Acids*
  • Dose-Response Relationship, Drug
  • GABA Antagonists / pharmacology
  • GABA-A Receptor Antagonists
  • GABA-B Receptor Antagonists
  • Gabapentin
  • Ligation
  • Male
  • Muscle Weakness / physiopathology
  • Pain / drug therapy*
  • Pain / etiology
  • Pain / psychology
  • Peripheral Nervous System Diseases / complications*
  • Physical Stimulation
  • Rats
  • Rats, Sprague-Dawley
  • Subarachnoid Space / physiology*
  • gamma-Aminobutyric Acid*

Substances

  • Acetates
  • Amines
  • Analgesics, Non-Narcotic
  • Cyclohexanecarboxylic Acids
  • GABA Antagonists
  • GABA-A Receptor Antagonists
  • GABA-B Receptor Antagonists
  • gamma-Aminobutyric Acid
  • Gabapentin