Oligodendroglial apoptosis occurs along degenerating axons and is associated with FAS and p75 expression following spinal cord injury in the rat
Section snippets
Spinal cord injury
All experimental protocols of this study were approved by the animal care committee of the Toronto Western Hospital Research Institute in accordance with the policies established in the guide to the care and use of experimental animals prepared by the Canadian Council of Animal Care. All efforts were made to minimize the number of animals used and their suffering.
SCI at C7–T1 was performed using the clip compression model in adult female Wistar rats (220–260 g; Charles River Laboratories,
DNA electrophoresis
To demonstrate the occurrence of internucleosomal DNA fragmentation characteristic of apoptotic cell degeneration, we electrophoresed 35S-labeled DNA isolated from normal and injured spinal cord in 1.5% agarose (Fig. 1). DNA isolated from injured tissue exhibited prominent banding of degraded DNA at lower molecular weights, (a characteristic of apoptosis resulting from internucleosomal DNA fragmentation), with a concomitant non-banding smear of DNA typical of necrotic degeneration. DNA from
Discussion
In this study we show using agarose electrophoresis, TUNEL and electron microscopy that apoptosis occurs following cervical SCI in the rat clip compression model. To date, this work is the first to demonstrate apoptosis in an animal model of cervical SCI, the most commonly injured level in humans.70 Ultrastructural data and double labeling immunomicroscopy revealed that most of the apoptotic cells are oligodendrocytes, and that these cells are spatially associated with degenerating axons. This
Acknowledgements
This work was supported by a Premier's Research Excellence Award Grant, Medical Research Council/Canadian Neurotrauma Research Program Grant and a Cervical Spine Research Society Grant. S. Casha is supported by an Ontario Neurotrauma Foundation Fellowship Award. M. G. Fehlings is the recipient of an Ontario Ministry of Health Career Scientist Award.
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