Early exercise in spinal cord injured rats induces allodynia through TrkB signaling.
Rehabilitation is important for the functional recovery of patients with spinal cord injury. However, neurological events associated with rehabilitation remain unclear. Herein, we investigated neuronal regeneration and exercise following spinal cord injury, and found that assisted stepping exercise of spinal cord injured rats in the inflammatory phase causes allodynia. Sprague-Dawley rats with thoracic spinal cord contusion injury were subjected to assisted stepping exercise 7 days following injury. Exercise promoted microscopic recovery of corticospinal tract neurons, but the paw withdrawal threshold decreased and C-fibers had aberrantly sprouted, suggesting a potential cause of the allodynia. Tropomyosin-related kinase B (TrkB) receptor for brain-derived neurotrophic factor (BDNF) was expressed on aberrantly sprouted C-fibers. Blocking of BDNF-TrkB signaling markedly suppressed aberrant sprouting and decreased the paw withdrawal threshold. Thus, early rehabilitation for spinal cord injury may cause allodynia with aberrant sprouting of C-fibers through BDNF-TrkB signaling.
Endo
Teruaki
T
Department of Orthopedic Surgery, Jichi Medical University, Shimotsuke, Tochigi 329-0498, Japan.
Ajiki
Takashi
T
Inoue
Hirokazu
H
Kikuchi
Motoshi
M
Yashiro
Takashi
T
Nakama
Sueo
S
Hoshino
Yuichi
Y
Murakami
Takashi
T
Kobayashi
Eiji
E
D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000037:antagonists & inhibitors / Q000378:metabolism; D005260:Female; D036421:Nerve Fibers, Unmyelinated / Q000502:physiology* / Q000648:ultrastructure; D009416:Nerve Regeneration; D010805:Physical Conditioning, Animal; D051381:Rats; D017207:Rats, Sprague-Dawley; D020813:Receptor, trkB / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction; D013116:Spinal Cord / Q000502:physiology* / Q000648:ultrastructure; D013119:Spinal Cord Injuries / Q000378:metabolism / Q000503:physiopathology*
D019208:Brain-Derived Neurotrophic Factor; D020813:Receptor, trkB