Adrenergic sensitivity of uninjured C-fiber nociceptors in neuropathic rats.
10.3349/ymj.2000.41.2.252
- Author:
Taick Sang NAM
1
;
Dong Soo YEON
;
Joong Woo LEEM
;
Kwang Se PAIK
Author Information
1. Brain Research Institute and Department of Physiology, Yonsei University College of Medicine, Seoul, Korea. jwleem@yumc.yonsei.ac.kr
- Publication Type:Original Article ; Research Support, Non-U.S. Gov't
- Keywords:
Peripheral nerve injury;
neuropathy;
causalgia;
nociceptor;
alpha-1 adrenoceptor
- MeSH:
Animal;
Male;
Nerve Fibers/physiology*;
Nociceptors/physiology*;
Norepinephrine/pharmacology;
Pain/physiopathology*;
Rats;
Rats, Sprague-Dawley;
Receptors, Adrenergic, alpha-1/physiology*
- From:Yonsei Medical Journal
2000;41(2):252-257
- CountryRepublic of Korea
- Language:English
-
Abstract:
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 beta-fiber activity. Sympathetic excitation of nociceptive fibers was suppressed by alpha 1-antagonist prazosin, while it was unaffected by alpha 2-antagonist yohimbine. Most of these fibers were excited by intra-arterial injection of alpha 1-agonist phenylephrine, without being affected by an injection of alpha 2-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 alpha 1-adrenoceptors in the peripheral endings.
