The Effects of Cyclosporin A and Insulin on Ischemic Spinal Cord Injury in Rabbits

We examined the effects of cyclosporin A (CsA), a drug that inhibits mitochondrial permeability transition pore, and insulin on ischemic spinal cord damage in rabbits. We assigned rabbits to 5 groups (n = 6 in each); sham barrier-opened group (sham BO), barrier-opened group (BO), barrier-opened-CsA group (BO-CsA), barrier-opened-insulin group (BO-I), and barrier-opened-CsA-insulin group (BO-CsA-I). The blood-spinal cord barrier was opened to facilitate drug penetration by a mild injury to the lumber spinal cord on day 1. CsA (10 mg/kg per day IV) was administered on day 3 to day 5 (total 30 mg/kg). Insulin was administered 30 min before ischemia. In all groups, spinal cord ischemia was produced on day 5 by occluding the abdominal aorta for 13 min. Neurological and histopathological evaluations were performed 4 days after ischemia. In group BO-CsA, blood glucose concentrations were significantly larger compared with the other four groups, and no protection was observed. In contrast, hindlimb motor function in groups BO-I and Bo-CsA-I and histopathology in group BO-CsA-I were significantly better than in groups sham BO, BO, and BO-CsA. The results indicate that insulin protects against ischemic spinal cord injury, whereas the effect of CsA is, at best, minimal.