实验性出血性脑水肿水通道蛋白4表达与MRI变化的相关性研究

目的 研究大鼠脑出血后血肿周围水通道蛋白4(AQP4)的表达与MRI各项指标变化,探讨AQP4的表达变化规律与出血性脑水肿形成之间的关系. 方法 45只雄性SD大鼠按随机数字表法分为假手术组(n=15)及出血组(n=30),每组又均分为造模后l、2、3、5、7 d组.采用苍白球注射胶原酶造成大鼠脑出血模型,在造模后1、2、3、5、7d行MRI扫描,测量计算血肿周围水肿体积以及水肿区T1WI、T2WI及FLAIR序列的信号强度比,成像后分别于相应时间点处死大鼠,应用免疫组化染色观察AQP4的表达. 结果 各时间点出血组大鼠血肿周围AQP4的表达水平明显高于假手术组,比较差异有统计学意义(P＜0.05),AQP4表达与血肿周围脑水肿体积呈线型正相关关系(r=0.687,P＜0.05),AQP4的表达与血肿周围水肿区T2WI、FLAIR序列的信号强度比呈线型正相关关系(r=0.640,P＜0.05;r=0.662,P＜0.05). 结论 AQP4表达与出血性脑水肿的形成、发展密切相关,AQP4的过度表达可能促进了出血后脑水肿的形成.

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

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.