실험연구 : 척수손상 후 척수 내 GABA 체계의 손실이 중추 신경병증성 통증 유발의 원인이라는 행동학적 및 전기생리학적인 증거

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 micro- electrode (2 - 4 MΩ). 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. (Korean J Anesthesiol 2002; 42: 667-676)