신경병증성 통증모델 쥐에서 피부통각수용체의 민감화

Abstract

Background: Peripheral nerve injury leads to neuropathic pain. Although it has been accepted that both peripheral and central processes may play a role in the pathophysiology of these sensory abnormalities, the involvement of peripheral mechanisms is often overlooked. The present study was conducted using neuropathic rats to see if cutaneous were sensitized and developed adrenergic sensitivity after peripheral nerve injury. Methods: Single fiber recording thchnique was to record the neural activity of nociceptive fiber in sural or plantar nerves of control rats and of rats that had previously received the L5-L6 spinal nerve ligation (neuropathic rats).Mechancial and heat thresholds of the recorded fibers were determined using von Frey filaments and thermal stimulators, respectively, which were applied to somatic receptive fields. Responses to supranthreshold mechanical and heat stimuli were also studied. The adrenergic sensitivity of nociceptive fibers was investigated by injecting intra-arterially the a_1-adrenergic agonist, phenylephrine. Results: Both mechanical and heat thresholds of nociceptive fibers in neuropathic rats were significantly lowered than those in control rats. In responses to suprathershold stimuli, neuropathic nociceptive heat-suprathreshold response were not significantly different from those of control rats. About 10% of sampled nociceptive fibers in neuropathic rats responded to phenylephrine. Conclusions: The results suggest that nociceptive on the skin supplied by injured nerves are sensitized to both mechanical and heat stimuli, and develop adrenergic sensitivity following peripheral nerve injury. The sensitization and adernergic sensitivity of cutaneous nociceptive may play a role, in part, in the development of neuropathic pain.