Expression of AQP4 during acute stage of traumatic brain injury in rats

Objective To investigate the expression of aquaporin-4(AQP4) and its correlation with brain edema during the acute phase of severe traumatic brain injury(TBI) in rats.Methods Fifty-six adult male Wistar rats were randomized into seven experimental groups(0.5,2,6,12,24,48 and 72 h post-injury) and one control group.A severe TBI model generated with hydraulic impact was used.At each time spots,the water contents in the brain tissues were measured as wet-to-dry weight ratio and the expression of AQP4 mRNA was assessed by semi-quantitative RT-PCR.Results The expression of AQP4 mRNA was up-regulated 0.5 hours after injury,progressively enhanced from 2 h to 6 h to 12 h,peaked at 24 h(P0.05) and remained a high level at 72 h.A similar change was noted for water contents in brain tissues.Correlation analysis showed that the expression of AQP4 mRNA was positively correlated with brain water contents(r=0.095,P0.05).Conclusion The changes in AQP4 mRNA expression may be closely related to formation and progression of brain edema during the acute stage of severe traumatic brain injury.AQP4 may be playing an important role in brain edema after severe TBI.