Lilian Ngozi Nwosu email@example.com
Blocking the tropomyosin receptor kinase A (TrkA) receptor inhibits pain behaviour in two rat models of osteoarthritis
Nwosu, Lilian Ngozi; Mapp, Paul I.; Chapman, Victoria; Walsh, David A.
Paul I. Mapp
Professor VICTORIA CHAPMAN firstname.lastname@example.org
Professor of Neuropharmacology
David A. Walsh
Objectives: Tropomyosin receptor kinase A (TrkA) mediates nociceptor sensitisation by nerve growth factor (NGF), but it is unknown whether selective TrkA inhibition will be an effective strategy for treating osteoarthritis (OA) pain. We determined the effects of a TrkA inhibitor (AR786) on pain behaviour, synovitis and joint pathology in two rat OA models.
Methods: Knee OA was induced in rats by intraarticular monosodium-iodoacetate (MIA) injection or meniscal transection (MNX) and compared with saline injected or sham-operated controls. Pain behaviour was assessed as weight-bearing asymmetry and paw withdrawal threshold to punctate stimulation. Oral doses (30 mg/kg) of AR786 or vehicle were administered twice daily in either preventive (day −1 to –27) or treatment (day 14–28) protocols. Effect maintenance was evaluated for 2 weeks after treatment discontinuation. Alterations in knee structure (cartilage, subchondral bone and synovium) were examined by macroscopic visualisation of articular surfaces and histopathology.
Results: Preventive AR786 treatment inhibited pain behaviour development and therapeutic treatment attenuated established pain behaviour. Weight-bearing asymmetry increased 1 week after treatment discontinuation, but remained less than in vehicle- treated arthritic rats, whereas paw withdrawal thresholds returned to levels of untreated rats within 5 days of treatment discontinuation. AR786 treatment reduced MIA-induced synovitis and did not significantly affect osteochondral pathology in either model.
Conclusions: Blocking NGF activity by inhibiting TrkA reduced pain behaviour in two rat models of OA. Analgesia was observed both using preventive and treatment protocols, and was sustained after treatment discontinuation. Selective inhibitors of TrkA therefore hold potential for OA pain relief.
|Journal Article Type||Article|
|Journal||Annals of the Rheumatic Diseases|
|Publisher||BMJ Publishing Group|
|Peer Reviewed||Peer Reviewed|
|APA6 Citation||Nwosu, L. N., Mapp, P. I., Chapman, V., & Walsh, D. A. (in press). Blocking the tropomyosin receptor kinase A (TrkA) receptor inhibits pain behaviour in two rat models of osteoarthritis. Annals of the Rheumatic Diseases, 75(6), https://doi.org/10.1136/annrheumdis-2014-207203|
|Copyright Statement||Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0|
Copyright information regarding this work can be found at the following address: http://creativecommons.org/licenses/by/4.0
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