The relationship between the change of aquaporin4, brain edema and neuronal function score of fluid percussion brain injury in rats

Objective To observe the relationship between neuronal function score, brain edema and aquaporin4(AQP4) expression of fluid percussion brain injury in rats. Methods The fluid percussion models of brain injury of rats were established by using the improved device. Nervous function score, brain water content, histological changes, AQP4 expression were observed by Shapira and Wahld method, dry-wet measure, light microscopy, immunohistochemistry and western blot at 1h, 6h, 12h, 24h, 3d and 7d after operation respectively. Results Nervous function score in TBI group decreased at 12h(11.17±1.32), reached its minimum at 24h(10.17 ±0.75), and recoved partially at 3rd day(10.66±1.37). The water content obviusly increased in those of TBI group at 12h((80.27±1.47)%), reached its peak at 24h((82.19±0.97)%), and then began to drop at 3d ((81.74±1.69)%), while Western blot showed that AQP4 immunoreactive expression obviusly increased at 12h(OD: 0.65±0.05), reached its maximum at 24h(OD: 0.72±0.08), and decreased at 3d(OD: 0.56±0.07), and immunohistochemistry showed the same trendency of AQP4 expression as that of Western blot. The linear regression analysis indicated that nervous function score had a negtive correlation with expression of AQP4 in edematous brain and change of brain water content respectively(r=-0.615, P<0.01; r=-0.605, P<0.05). Conclusion Nervous function score of fluid percussion brain injury in rats decrease, has negative relationship with brain edema and AQP4 expression, and possible mechanisms is that AQP4 is indirectly involed in nerve function impairment by mediating brain edema. Key words: Brain injury; Fluid percussion; Brain edema; Aquaporin4