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Published on: June 26, 2019
The onset of hyperreflexia in the rat following complete spinal cord transection
C Yates1, A Charlesworth, S R Allen
1Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA.
Study Design:
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.
Setting:
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.
Conclusion:
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.
