Daily passive cycling attenuates the hyperexcitability and restores the responsiveness of the extensor monosynaptic reflex to quipazine in the chronic spinally transected rat.
Activity-based interventions such as locomotor training or passive cycling have a positive influence on the spinal circuitry and recovery following a spinal cord injury (SCI). The use of quipazine in combination with exercise training has demonstrated a greater functional recovery than has exercise training alone. However, the influence of exercise or training on the responsiveness of the spinal cord to quipazine has not been examined following a chronic spinal transection. The purpose of this study was to characterize the flexor and extensor monosynaptic reflex (MSR) response pre- and post-quipazine in chronic complete spinally transected rats that either underwent daily passive cycling for 3 months or did not receive passive cycling. Following a chronic spinal transection, the extensor MSR demonstrated a hyperreflexive response (fivefold increase) to afferent stimuli, and did not respond to quipazine injection. With daily passive cycling, the extensor MSR hyperexcitability was attenuated, and the MSR amplitude increased 72% following quipazine injection (p<0.004), which was comparable to the extensor MSR response (94%) in the control group. For both chronic spinal transection groups, the flexor MSR amplitudes were not altered following quipazine injection, whereas in the control group the flexor MSR amplitude increased 86% in response to quipazine (p<0.004). These results demonstrate that passive cycling attenuates the hyperreflexive response of the extensor MSR following a chronic SCI, and restores the MSR response to quipazine.
1 Spinal Cord Research Centre, Department of Physiology and, University of Manitoba , Winnipeg, Manitoba, Canada .
Jeremy W
JW
Chopek
Christopher W
CW
MacDonell
Kalan
K
Gardiner
Phillip F
PF
Gardiner
D000818:Animals; D003131:Combined Modality Therapy; D004195:Disease Models, Animal; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D011814:Quipazine / Q000008:administration & dosage / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D020127:Recovery of Function / Q000187:drug effects / Q000502:physiology*; D012023:Reflex, Monosynaptic / Q000187:drug effects / Q000502:physiology*; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology*; D013119:Spinal Cord Injuries / Q000188:drug therapy / Q000628:therapy*
D017366:Serotonin Receptor Agonists; D011814:Quipazine
exercise; monosynaptic reflex; motor output; serotonin; spinal transection