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Osteoarthr. Cartil. · Jun 2017
Lysophosphatidic acid provides a missing link between osteoarthritis and joint neuropathic pain.
- J J McDougall, S Albacete, N Schuelert, P G Mitchell, C Lin, J L Oskins, H H Bui, and M G Chambers.
- Department of Pharmacology, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, B3H 4R2, Canada; Department of Anaesthesia, Pain Management & Perioperative Medicine, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, B3H 4R2, Canada. Electronic address: jason.mcdougall@dal.ca.
- Osteoarthr. Cartil. 2017 Jun 1; 25 (6): 926-934.
ObjectiveEmerging evidence suggests that osteoarthritis (OA) has a neuropathic component; however, the identity of the molecules responsible for this peripheral neuropathy is unknown. The aim of this study was to determine the contribution of the bioactive lipid lysophosphatidic acid (LPA) to joint neuropathy and pain.DesignMale Lewis rats received an intra-articular injection of 50 μg of LPA into the knee and allowed to recover for up to 21 days. Saphenous nerve myelination was assessed by g-ratio calculation from electron micrographs and afferent nerve damage visualised by activation transcription factor-3 (ATF-3) expression. Nerve conduction velocity was measured electrophysiologically and joint pain was determined by hindlimb incapacitance. The effect of the LPA antagonist Ki-16425 was also evaluated. Experiments were repeated in the sodium monoiodoacetate (MIA) model of OA.ResultsLPA caused joint nerve demyelination which resulted in a drop in nerve conduction velocity. Sensory neurones were ATF-3 positive and animals exhibited joint pain and knee joint damage. MIA-treated rats also showed signs of demyelination and joint neuropathy with concomitant pain. Nerve damage and pain could be ameliorated by Ki-16425 pre-treatment.ConclusionIntra-articular injection of LPA caused knee joint neuropathy, joint damage and pain. Pharmacological blockade of LPA receptors inhibited joint nerve damage and hindlimb incapacitance. Thus, LPA is a candidate molecule for the development of OA nerve damage and the origin of joint neuropathic pain.Copyright © 2016 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.
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