The Effects Of Methylprednisolone On Brain Edema And AQP4 Expression In Rats With Severe Traumatic Brain Injury At High Altitude Area

Objective:To study the changes of cerebral edema and the expression of aquaporin4(AQP4)at different time points aftersevere brain injury in rats at high altitude area and explore its mechanism of cerebral edema.Canmethylprednisolonedecreased cerebral edema degree? In this study,we use the advantage of high altitudeto simulate the patients with severe craniocerebral injury in rats.Methods:144 adult male SD rats with weight of about 270 ±40g were randomly divided into 4 groups: blank group,sham operation group,control group and methylprednisolone group,with an average of each group of 36 rats,each group was subdivided into 3 groups according to 24 h,72h,and 168 h after the success of modeling.Rats in blank group were not treated,rats in sham operation groupwere stitched after scalp incision and removal of skull,the other two groupsrats established the model of severe traumatic brain injury by free fall brain injury method.Rats in methylprednisolone group were given intraperitoneal injection of methylprednisolone(30mg/kg)after the model was established,subsequently changed to(10mg/kg/6h)intervention,the rats in other groups were injected with the same amount of physiological saline.Each subgroups rats were sacrificed according to their own modeling time points.Finally,the water content of brain tissue and the expression of AQP4 were measured by dry-wetweight method and immunohistochemistry,statistical analysis data at last.Results:At high altitude,the water content of the rat model began to increase after injury,to 24h(81.54±0.72)%,72 h(83.34±0.51)% reached the peak and began to decrease,to 168h(80.33±0.67)%reduced to less than 24 hours water content,the peak of cerebral edema in rats was 3d after injury and decreased at 7d.The positive expression of AQP4 after injury were increasedwith time and to 24 h,the integrated optical density(IOD)value(14220.3 + 437.15),72 h reached the peak(17879.9 + 526.29)began to decrease,168h(11431 + 411.18)is lower than the expression level recovered to 24 hours,the change trend of brain water content and at the same time the rate of change by linear correlation analysis for positive correlation.Model rats after methylprednisolone intervention,brain water content rateat different time points 24 h,72h,and 168h(80.10 + 0.24,82.53 + 0.22,79.09 + 0.43)% and the IOD of positive expression of AQP4(11454.4 + 397.06,14521.7 + 434.43,8639.5 + 387.2)were lower thancontrol group at the same time(P < 0.05),suggesting that MPmay have some effects on the cerebral edema caused by trauma,the expression of AQP4 has a negative regulatory role.Conclusion: The peak of traumatic cerebral edema in high altitude area was 3d after injury and decreased at 7d.The progression of cerebral edema was positively correlated with the expression of AQP4.Methylprednisolone can negatively regulate the expression of AQP4 and reduce the degree of cerebral edema caused by trauma.