The Affect Of Dexmedetomidine On Aquaporin4 (AQP4) Expression In Rats With Traumatic Brain Injury

[Objectives] To investigate the effect of dexmedetomidine on expression level of cerebral aquaporin-4(AQP-4) and the change of brain edema during traumatic brain injury (TBI) in rats.[Methods] We choosed clean and ripe SD rats. Their weight was controlled between 220 and 250g.l80 SD rats were divided randomly into sham operation group(control group, n=60)、TBI model group(model group, n=60) and dexmedetom-idine treatment group(treatment group,n=60).The experimental TBI model was established by bumpiness of free falling body according to Feeney’s. After TBI model was established, Rats in treatment group were continous tail vein pumping with dexmedetomidine after TBI model was established, Rats in control group and model group were continous tailvein pumping with normal saline after TBI model was established.After model was established 6h,24h,48h and 72h,All rats are scored with NSS(Neurological Severity Score),then all rats were cut off the head to take out the brain. The changes of brain water content and permeability of blood-brain barrier(BBB) were measured by the methods of wet and dry weight and Evans blue fluorometry. The expression of AQP-4 protein was examined by western blot.[Results]:The NSS score、water content of brain tissue、EB content in the contusion side、the expression of AQP-4 protein in model group and treatment group were higher than control group (P<0.05);The model group’s NSS score water content of brain tissue、EB content in the contusion side、the expression of AQP-4 protein were higher than treatment group (P<0.05);After model group and treatment group was established 6h, the NSS score, water content of brain tissue、EB content in the contusion side and expression of AQP-4 protein were increase.They reached the summit at 24h after operation, afterward dropped gradually,and still maintained at the high level after 72h(p<0.05).[Conclusions]The change of AQP-4 Protein expression are positively correlated with the NSS score、water content of brain tissue、EB content in the contusion side. Brain edema reached the summit at 24h after operation.The level of brain edema are positively correlated with AQP-4 Protein expression and BBB permeability.with the reduce of AQP-4 Protein expression and BBB permeability,rats’ brain edema gradually reduce.The AQP-4 Protein expression in Rats that pumped with dexmedetomidine after TBI model were restrained in the early stage(within 24h) of injury. Dexmedetomidine also can decrease BBB permeability and brain edema in TBI rats.