Background: Various caspases have been implicated in the development of secondary damage after spinal cord injury (SCI). Anticaspase therapy that targets only one caspase has been investigated in a variety of in vitro and in vivo studies. This study examined the neuroprotective effects of Q-VD-OPh, a pan-caspase inhibitor, in a rat model of SCI.
Methods: Thirty Wistar albino rats were divided into 3 groups of 10 each: the sham-operated controls (group 1), the trauma-created controls (group 2), and the QVD- OPh-treated rats (group 3). An SCI (a trauma of 40 g-cm) was produced at the thoracic level (T8-T10) by the weight-drop technique. The response to injury and the neuroprotective effects of Q-VD-OPh were investigated by histopathologic examination and terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) 24 hours and 5 days after trauma. The inclined plane technique of Rivlin and Tator and a modified version of Tarlov's grading scale were used to assess the functional status of the rats 24 hours, 3 days, and 5 days after injury.
Results: Twenty-four hours after trauma, light microscopic examination of a specimen taken from group 2 rats revealed hemorrhage, necrosis, vascular thrombi, and edema. Group 3 tissue samples showed similar features at that time. Twenty-four hours after trauma, the mean apoptotic cell number was 4.47 +/- 0.35 cells in group 2 and 1.58 +/- 0.33 in group 3. Five days after injury, the mean apoptotic cell count was 4.35 +/- 0.47 in group 2 and 1.25 +/- 0.34 in group 3. Thus the number of TUNEL-positive cells in an injured spinal cord was greatly reduced by treatment with Q-VDOPh. The neurologic function scores (both the inclined plane performance and motor grading scores) were significantly better in the Q-VD-OPh-treated group than in the trauma-created control group.
Conclusion: The marked antiapoptotic properties of Q-VD-OPh due to the inhibition of all caspases render it a promising novel agent. A therapeutic strategy using Q-VD-OPh may eventually lead to the effective treatment of SCI in humans.