The onset of hyperreflexia in the rat following complete spinal cord transection.
METHODS
Hyperreflexia occurs after spinal cord injury (SCI) and can be assessed by measuring low frequency-dependent depression of the H-reflex. Previous studies showed the time course for the onset of hyperreflexia to occur between 6-28 days in the contusion model of SCI.


OBJECTIVE
To determine the time course of the onset of hyperreflexia in the transection model of SCI and examine changes in Connexin-36 (Cx-36) protein levels in the lumbar enlargement of animals.


METHODS
Spinal Cord Injury Mobilization Program of the Center for Translational Neuroscience, the research arm of the Jackson T. Stephens Neuroscience Institute, Little Rock, AR, USA.


METHODS
Adult female rats underwent transection at T10 level. Low frequency-dependent depression of the H-reflex was tested at 7, 14 and 30 days post-transection. Lumbar enlargement tissue was harvested following reflex testing and western blots were performed after immunoprecipitation to compare Cx-36 protein levels.


RESULTS
Significant decreases in low frequency-dependent depression of the H-reflex were observed in animals tested 14 and 30 days post-transection compared with control animals, but it was not different from control animals at 7 days. Significant decreases in Cx-36 protein levels were observed in animals 7 days post-transection compared with controls.


CONCLUSIONS
Rats transition to a state of hyperreflexia between 7 and 14 days post-transection. Cx-36 protein levels decreased at 7 days post-transection and gradually returned to control levels by 30 days post-transection. These data suggest there may be a relationship between changes in neuronal gap junction protein levels and the delayed onset of hyperreflexia.
Yates
C
C
Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Charlesworth
A
A
Allen
S R
SR
Reese
N B
NB
Skinner
R D
RD
Garcia-Rill
E
E
D000818:Animals; D015415:Biomarkers / Q000032:analysis / Q000378:metabolism; D017630:Connexins / Q000032:analysis / Q000378:metabolism; D004195:Disease Models, Animal; D018450:Disease Progression; D015536:Down-Regulation / Q000502:physiology; D005260:Female; D017629:Gap Junctions / Q000378:metabolism; D006181:H-Reflex / Q000502:physiology; D009482:Neurophysiology; D010812:Physical Stimulation; D011237:Predictive Value of Tests; D051381:Rats; D017207:Rats, Sprague-Dawley; D012021:Reflex, Abnormal / Q000502:physiology*; D013116:Spinal Cord / Q000503:physiopathology*; D013119:Spinal Cord Injuries / Q000503:physiopathology*; D013904:Thoracic Vertebrae; D013997:Time Factors; D000097004:Gap Junction delta-2 Protein
D015415:Biomarkers; D017630:Connexins; D000097004:Gap Junction delta-2 Protein