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KMID : 0311120000410020252
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Yonsei Medical Journal
2000 Volume.41 No. 2 p.252 ~ p.257
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Adrenergic Sensitivity of Uninjured C-fiber Nociceptors in Neuropathic Rats
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Joong Woo Leem/Taick Sang Nam
Dong Soo Yeon/Joong Woo Leem/Kwang Se Paik
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Abstract
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We investigated the adrenergic sensitivity of afferent fibers in the L4 dorsal roots of rats with a unilateral ligation of the L5-L6 spinal nerves. About 12% of nociceptive fibers on the affected side were excited by sympathetic stimulation or by intra-arterial injection of norepinephrine which did not affect A β-fiber activity. Sympathetic excitation of nociceptive fibers was suppressed by α1-antagonist prazosin, while it was unaffected by α2-antagonist yohimbine. Most of these fibers were excited by intra-arterial injection of α1-agonist phenylephrine, without being affected by an injection of α2-agonist clonidine. Sympathetic excitation was blocked by lidocaine applied near the receptive fields of recorded fibers. The results suggested that some nociceptors remaining intact after partial nerve injury become sensitive to sympathetic activity by the mediation of α1-adrenoceptors in the peripheral endings.
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KEYWORD
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Peripheral nerve injury, neuropathy, causalgia, nociceptor, alpha-1 adrenoceptor,
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