Investigation of the neuroprotective effectiveness of remote ichemic preconditioning in the medulla spinalis trauma model created in rats

Investigation Of The Neuroprotective Efficacy Of Remate Ischemic Preconditioning In A Rat Model Of Medulla Spinalis Trauma Dr. Meriç BAYRAM, Hacettepe University Faculty of Medicine Anesthesiology and Reanimation Department Ankara 2022. To investigate the neuroprotective effect of remote ischemic preconditioning (RIPC) and the role of kynurenic acid (KYNA), a product of tryptophan metabolism, in the mechanism of RIPC by comparing blood S100B levels and histopathological images in rats with spinal cord injury (SCI). Experimental animal study. 31 male Spraque-Dawley rats were divided into 3 groups. Group I (Sham, n=9): After making only an incision, the skin was closed without any procedure. Group II (I/R, n=11): After 1 min of total ischemia, reperfusion was applied to the spinal cord for 1 h. Group III (RIPC+I/R, n=8): After 3 cycles of 10-minute RIPC applied to the right hind leg, I/R was performed in the medulla spinalis. Blood was collected for biochemical evaluation (S100B and KYNA) at the 1st hour after the procedure. The rats were sacrificed, and medulla spinalis tissue samples were taken for histopathological evaluation. KYNA and S100B levels were significantly different between the sham and I/R groups (p = 0.016 and p = 0.022, respectively). Although post-hoc pairwise comparisons for the I/R and RIPC+I/R groups were not significant in either comparison, rats treated with RIPC had relatively lower concentrations of KYNA and S100B than in the I/R group alone. Histological analyses revealed significantly higher white and gray matter damage scores in both the I/R and RIPC+I/R groups than in the sham group (p = 0.001 and p < 0.001, respectively). Although the median scores for white and gray matter and the regions they contain were relatively higher in the RIPC+I/R group than in the I/R group, the results were statistically similar by pairwise comparison. There was no significant correlation between KYNA concentration, S100B concentration, and histological scores. This study showed that S100B and KYNA levels and histological scores for neuronal damage were significantly increased in a rat spinal I/R injury model, although not statistically significant. S100B and KYNA levels were lower in the RIPC+I/R group than in the I/R group. Histological evaluation revealed that, spinal cord injury score was higher in the RIPC+I/R group than in the I/R group. Keywords: Medulla spinalis, remote ischemic preconditioning, ischemia, reperfusion, S100B, KYNA