Korean J Anesthesiol.  2002 May;42(5):667-676. 10.4097/kjae.2002.42.5.667.

Loss of the Spinal GABAergic System Is Involved in Chronic Central Pain Following a Spinal Cord Injury; Behavioral and Electrophysiological Evidences

Affiliations
  • 1Department of Physiology, Yonsei University College of Medicine, Seoul, Korea. jwleem@yumc.yonsei.ac.kr
  • 2Department of Anesthesiology, Yonsei University College of Medicine, Seoul, Korea.

Abstract

BACKGROUND: Allodynia, hyperalgesia, and spontaneous pain are symptoms characterized by chronic central pain which was frequently observed following a spinal cord injury (SCI). However, the underlying mechanism has not been fully understood. This study was conducted to investigate whether the loss of the GABAergic system in the spinal dorsal horn was involved in the development of central pain following a spinal cord injury.
METHODS
SCI was induced by a hemisection of the spinal cord at T13 in adult male Sprague-Dawley rats. Mechanical allodynia was tested by measuring paw withdrawal frequency in response to repeated applications of a von Frey hair to the plantar surface of the hind-paw. Single neuronal activity of the dorsal horn neurons (L4 L6) was recorded extracellularly using a carbon filament-filled glass microelectrode (2 4 MOhm). The drugs were intrathecally or topically administrated on the spinal surface for behavioral and electrophysiological experiments, respectively.
RESULTS
After a left spinal hemisection at T13, behavioral signs of mechanical allodynia developed on both hind-paws and responsiveness of spinal dorsal horn neurons increased on both sides of the spinal dorsal horn. GABA receptor agonists including GABAA and GABAB receptor subtypes suppressed mechanical allodynia on both sides of hind-paws and decreased responsiveness of spinal dorsal horn neurons on both sides of spinal cord.
CONCLUSIONS
These results indicate that a loss of the GABAergic system within the spinal cord plays a key role on the development of central pain following a spinal cord injury.

Keyword

Baclofen; central pain; GABA; muscimol; spinal cord injury

MeSH Terms

Adult
Animals
Baclofen
Carbon
GABA Agonists
gamma-Aminobutyric Acid
Glass
Hair
Horns
Humans
Hyperalgesia
Male
Microelectrodes
Muscimol
Neurons
Posterior Horn Cells
Rats, Sprague-Dawley
Spinal Cord Injuries*
Spinal Cord*
Baclofen
Carbon
GABA Agonists
Muscimol
gamma-Aminobutyric Acid
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