Correlations between aquaporin 4 expression and MRI changes in rats with experimental hemorrhagic cerebral edema

Abstract

Objective To study the relation between aquaporin 4 (AQP4) expression in the perihematomal tissue and changes of MRI indicators after intracerebral hemorrhage of rats, and explore the relationship between AQP4 expression and formation of hemorrhagic brain edema. Methods Forty-five male SD rats were randomized into sham-operated group (n=15) and hemorrhage group (n=30). The rats of these groups were equally subdivided into the 1', 2nd, 3rd, 5th and 7th d measurement groups, respectively. The models of intracerebral hemorrhage were established by infusing collagenase into globus pallidus of the rats. MRI was performed 1, 2, 3, 5 and 7 d after the success of model making;edema volume around the hematoma and signal intensity ratio of T1WI, T2WI, and FLAIR sequences in the edema zone were measured and calculated. The rats were sacrificed at the corresponding time point after imaging. Immunohistochemistry staining was performed to observe the expression of AQP4 at each time point. Results The AQP4 expression level of perihematomal tissue in the hemorrhage group was obviously higher than that in the sham-operated group (P＜0.05). Liner positive correlation between the AQP4 expression level and the volume of cerebral edema around the hematoma was noted (r=0.687,P＜0.05). Liner positive correlations between the AQP4 expression level and both signal intensity ratio of T2WI and FLAIR sequences in the cerebral edema region were also found (r=0.640, 0.662; P＜0.05).Conclusion AQP4 has a close relation with the formation and expansion of hemorrhagic cerebral edema; over-expression of AQP4 may promote the formation of edema after intracerebral hemorrhage. Key words: Aquaporin 4; Cerebral hemorrhage; Brain edema; MRI