肝硬化肝性脑病大鼠脑水通道蛋白-4的表达与脑水肿的关系

Relationship between aquaporin-4 expression and brain edema in cirrhotic rats with hepatic encephalopathy

目的:探讨肝硬化肝性脑病脑水肿的发生机制,为治疗脑水肿新方法的发现提供理论依据.方法:实验大鼠随机分为正常组(n=10)、正常氨负荷组(n=10)、肝硬化组(n=20)和肝硬化氨负荷组(n=20).后2组给予400g/LCCl4橄榄油,按0.2mL/kg腹腔注射,2次/wk,共12wk.前两组给与橄榄油,注射剂量、部位、频次、时间同后两组.正常氨负荷组、肝硬化氨负荷组分别在最后1次给药2d后,给与乙酸胺盲肠注射.4组大鼠通过尾静脉注射伊文思蓝(EB)应用干式生化法测量动脉血氨,比色法测量EB含量,干-湿重法测量脑含水量,免疫组化法染色并通过图像分析系统分析脑组织中AQP4的表达.结果:肝硬化组动脉血氨与正常组、正常氨负荷组比较有差异性(97.20±29.66μmol/Lvs42.62±10.11,59.33±15.06μmol/L,均P<0.05),肝硬化氨负荷组的动脉血氨(420.18±75.91μmol/L)与其他各组比较有明显的差异性(P<0.01).肝硬化组EB和脑含水量与正常组、正常氨负荷组比较没有差异性,而肝硬化氨负荷组与其他各组比较有差异性(1.96±0.55μg/gvs1.41±0.46,1.19±0.38,1.05±0.18μg/g;75.14±5.68vs65.58±4.14,62.14±2.29,66.27±4.57,均P<0.05).肝硬化大鼠AQP4表达部位与正常大鼠一致,但肝硬化大鼠给与氨负荷后,无论是平均吸光度还是显色阳性面积均较正常组增高(P<0.05).结论:AQP4可能在肝硬化肝性脑病大鼠脑水肿形成中起一定的作用.

AIM： To investigate the mechanism of brain edema in cirrhotic rats with hepatic encephalopathy, and to provide the theoretical basis for management of brain edema. METHODS： Rats were divided into 4 groups randomly： normal group （n = 10）, normal ammonia burden group （n = 10）, cirrhosis group （n = 20）, cirrhosis ammonia burden group （n = 20）. After models were generated successfully, the arterial plasma ammonia was measured by dry biochemical method, and the evans blue （EB） content was examined by colorimetric method; the brain water content （BWC） was measured by means of dry-wet method and the aquaporin-4 （APQ-4） in the brain tissue was assessed by immunohistochemistry. RESULTS： In comparison with that in the normal group and nomal ammonia burden group, the arterial plasma ammonia was significantly increased in the cirrhosis group and cirrhosis ammonia burden group （420.18 ± 75.91, 97.20 ± 29.66 μmol/L vs 42.62 ± 10.11, 59.33 ± 15.06 μmol/L; P 〈 0.05 or P 〈 0.01）. The EB content （1.96 ± 0.55 μg/g） and brain water content （75.14 ± 5.68） in the cirrhosis ammonia burden group were higher than those in the nomal group, nomal ammonia burden group, and cirrhosis group （1.96 ± 0.55 μg/g vs 1.05 ± 0.18, 1.19 ± 0.38, 1.41 ± 0.46 μg/g; 75.14 ± 5.68 vs 62.14 ± 2.29, 66.27 ± 4.57 65.58 ± 4.14; all P 〈 0.05）. The location of APQ-4 expression in cirrhotic rats was consistent with that in normal rats, but both the intensity and area of APQ-4 expression were increased as compared with those in normal controls （P 〈 0.05）. CONCLUSION： APQ-4 expression is up-regulated in cirrhotic rats with hepatic encephalopathy, suggesting that APQ-4 may play a role in the oc- currence of hepatic encephalopathy.