Effect of local irrigation with artificial cerebrospinal fluid on brain edema and aquaporin-4 after experimental traumatic brain injury

Objective To investigate the effect of local irrigation with artificial cerebrospinal fluid on brain edema and the change of expression of aquaportin-4(AQP4) resulted from traumatic brain injury(TBI) in rats. Methods The rats were subjected to brain injury lateral controlled impact on cortex. Thirty minutes after TBI,local irrigation treatment was implemented with normal saline or artificial cerebrospinal fluid for 3 hours. Rats were decapitated 4h,1 day,3 days,5 days,7 days after injury. The volume of water in the injured parietal cerebral cortex and the AQP4 mRNA level were measured. Results In TBI rats,elevated brain edema was detected significantly at 4 h,1 day and 3 days after TBI in the injured parietal cerebral cortex,and began to decline at 5 and 7 days. The elevation of brain edema was significantly reduced by posttraumatic local irrigation,especially with artificial cerebrospinal fluid. After TBI,the expression of AQP4 mRNA increased significantly at 4 h,peaked on 1～3 d,and remained high for 5 d compared with normal group(P0.05) ;decreased significantly at 4 h,1 d,3 d,and 5 d after local irrigation treatment especially with artificial cerebrospinal fluid. Conclusion Local irrigation with artificial cerebrospinal fluid can reduce traumatic brain edema significantly. Down-regulation of AQP-4 expression may be one of its neuroprotective mechanisms.