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

Objective To investigate the expression of aquaporin-4(AQP4) and its correlation with brain edema at the acute phase after severe traumatic brain injury(TBI) in rats.Methods Forty-nine adult male SD rats were divided into the experimental groups designated 4 h,8 h,12 h,24 h,72 h and 5 d after the injury and control group.A severe TBI model was used.The water contents in the brain tissues were measured by the wet and dry weight method.The sodium(Na+) and potassium(K+) contents were measured by atomic absorption spectrophotometry.The blood-brain barrier(BBB) permeability was measured by Evans blue extravasation.The expression of AQP4 mRNA was assessed by RT-PCR.Results The expression of AQP4 mRNA significantly increased after 4 hours,8 hours,12 hours,get the highest level at 24 hours(P0.05),keep high level at 3d and then decreased gradually at 5 d.The changes of brain water content and Na+ content was the same as that of AQP4 mRNA expression.Correlative analysis results showed that the expression of AQP4 mRNA was positive correlated with the brain water content(P0.05) and the change of EB content(P0.05).Conclusion The change of AQP4 mRNA expression is closely related to the destruction of BBB and the formation and development of brain edema during the acute stage after severe traumatic brain injury.AQP4 maybe participated in the brain edema formation after severe traumatic brain injury and plays an important role.