Effect Of Ischemic Post-conditioning On Spinal Cord Ischemic-reperfusion Injury In Rabbits

Objectives To investigate the protective effect of ischemic post-conditioning (Post-con) on ischemia-reperfusion injury of rabbit spinal cord with comparison to ischemic preconditioning (IPC), and whether there was an additive effect when ischemic preconditioning and post-conditioning were combined.Methods The spinal cord ischemia was produced by infrarenal occlusion of the aorta (AOC). 40 New Zealand White rabbits were randomly divided into 4 groups: Group Control (n=10), no intervention but the aortic occlusion for 30 minutes; Group ICP (n=10) 3 cycles of 3-min AOC plus 3-min reperfusion before the 30-min AOC; Group Post-con (n=10), 3 cycles of 3-min reperfusion plus 3-min AOC immediately upon reperfusion after 30-min AOC; Group IPC+Post-con (n=10), the above IPC and Post-con were combined. At 6h, 24h and 48h after the reperfusion, the neurologic function was assessed respectively according to the Tarlov score, and at 48h, the spinal cords were harvested for the histopathologic evaluation, and the number (N) of intactα-motor neurons in the anterior horn was counted.Results The median count (and quartiles) of the intactα-neuron numbers was greatest in group Post-con 73(69-76) and group IPC+Post-con 29(22-42) compared to that in group C 6(4-9) and group IPC 15(11-18) (p<0.001). However, there was no difference in neurologic function in any of the four groups, although the incidence of paraplegia was lower in group Post-con (70%, 7/10) than that in group C (90%, 9/10). Furthermore, the group Post-con had an even better histopathologic result compared to group IPC+Post-con (p<0.001).Conclusions Our results showed that the Post-con could improve the histopathologic status of the spinal cord subjected to ischemic insult, although there was no functional improvement. And no additional protective effect was observed when Post-con combined with IPC.