Neuroprotective Effect of Ischemic Preconditioning in Traumatic Brain Injured Rats

Objective To test the hypothesis that a transient non-lethal ischemia (ie. ischemic preconditioning(IPC)) would protect against subsequent traumatic brain injury (TBI) using( 1)H-magnetic resonance spectroscopy (MRS). Method Sprague-Dawley rats were randomized to sham ischemia procedures followed by TBI, IPC followed by TBI, and IPC followed by sham TBI. IPC was induced by 20 min of right common carotid artery occlusion 24 hour prior to TBI, and experimental injury was induced using lateral fluid percussion model of moderate severity. We measured metabolic changes with H-1-MRS and conducted motor function and 4 arm maze tests to identify neurobehavioral deficits and cognitive deficits, respectively, at 1 day to 4 weeks post-injury. Results The NAA/Cr ratios in the affected hemisphere were significantly lower in TBI than in IPC-TBI gaup at 2 (p=0.006) and 4 (p=0.012) weeks and in the unaffected hemisphere at 4 weeks (p=0.030). TB1 group also showed a trend towards reduction in NAA/Cho ratio in the affected hemisphere at 4 weeks (p=-0.054). Conclusion Brief IPC 24 hours before moderate lateral fluid percussion brain injury increases the resistance to brain damage and that is associated with changes in brain metabolites. These findings indicate that IPC induces neuroprotection against TBI in rat brains.