Pretreatment with calpain inhibitor CEP-4143 inhibits calpain I activation and cytoskeletal degradation, improves neurological function, and enhances axonal survival after traumatic spinal cord injury |
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Authors: | Schumacher P A Siman R G Fehlings M G |
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Affiliation: | Division of Neurosurgery and Playfair Neuroscience Unit, Toronto Western Hospital, Ontario, Canada. |
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Abstract: | The pathophysiology of traumatic spinal cord injury (SCI) involves abnormal activation of the neutral cysteine protease calpain I (EC 3.4.22.17). In the present study we examined the effect of the calpain inhibitor CEP-4143 on cytoskeletal protection and neurological recovery after SCI in adult rats. Microinjection of 50 mM CEP-4143 into the T7 vertebral segment 10 min before a 35-g clip compression injury resulted in inhibition of calpain activation at 2 and 4 h postinjury, as determined by western blotting for calpain I-mediated spectrin degradation, and significantly attenuated the degradation of dephosphorylated NF200 neurofilament protein at 4 and 8 h postinjury. To examine the in vivo chronic neuroprotective effects of CEP-4143, animals underwent microinjection with saline or 50 mM CEP-4143 10 min before injury, followed by weekly blinded behavioral assessments for 6 weeks. Animals receiving CEP-4143 treatment showed significant improvement over saline-treated controls on the Basso Beattie Bresnahan locomotor rating scale (p < 0.02) and inclined plane test (p < 0.05). Counts of neurons in the red nucleus retrogradely labeled by fluoro-gold after introduction distal to the injury site were significantly higher in CEP-4143-treated animals. Finally, morphometric assessment of the injury site by computer-assisted image analysis revealed significant tissue preservation in CEP-4143-treated animals. We conclude that the calpain antagonist CEP-4143 exhibits biochemical, behavioral, and anatomical neuroprotection following traumatic SCI. |
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Keywords: | Spinal cord injury Nerve tissue proteins Neurotrauma Calpain Neurofilament Treatment |
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