大鼠脑创伤半暗带水肿与水通道蛋白-4表达的相关性

摘要

目的 探讨大鼠脑创伤半暗带(TP)水肿与水通道蛋白-4(AQP4)表达之间的关系. 方法 88只成年雄性Wistar大鼠,按随机数字表法分为对照组(11只)和创伤组(77只),观察时相点为创伤后1,6,12,24,48,72 h、7 d,每个时相点11只.采用改良mFeeney法建立中度脑创伤模型,组织学观察脑组织水肿,免疫组化半定量IgG的表达观察血脑屏障(BBB)的变化,免疫荧光和Western blotting观察AQP4表达. 结果 对照组病理及IgG染色未见异常,AQP4表达量较少.创伤组伤后1h在创伤周边出现染色浅淡的TP,之后逐渐增加,12 h达到最宽,为(1.589±0.020) mm,之后变窄,除24 h与48 h和72 h与7d外,余各时相点差异均有统计学意义(P＜0.05).创伤组伤后1h创伤周边呈血管源性水肿,6h出现细胞内水肿,12h血管源性水肿与细胞内水肿均明显加重,72 h细胞内水肿占优势.IgG染色于1,12,48 h呈3度强阳性;6,24,72 h及7d呈1度弱阳性.创伤组伤后1 h AQP4表达下降为0.659±0.021,6 h稍回升为1.257±0.058,12 h达峰值2.499±0.136,之后又随损伤时间降低,24h为2.267±0.068,72 h再次上调为2.078±0.065,7d时基本恢复至基线水平1.280±0.065,除6h与7 d(P ＞0.05)、12h和24h(P＞0.05)、24 h和72 h(P ＞0.05)外,余各时相点之间比较差异有统计学意义(P＜0.05). 结论 创伤早期TP表现为以BBB破坏为特征的血管源性水肿,AQP4表达下调,随后AQP4表达上调,引起细胞内水肿,加重TP.AQP4可能参与机体的防御反应.%Objective To investigate the relationship between edema and aquaporin 4 (AQP4) within traumatic penumbra (TP) of rats with brain trauma.Methods Eighty-eight healthy adult Wistar rats were randomly divided into control group (n =11) and trauma group (n =77),according to the random number table.Trauma group were further subdivided into seven time points (1 h,6 h,12 h,24 h,48 h,72 h and 7 d) of 11 animals each.Brain tissue samples from the moderate brain models were collected to evaluate brain edema with histological observation,blood brain barrier (BBB) permeability with semiquantitative immunohistohemical staining of IgG,and AQP4 expression with immunofluorescence and Western blotting.Results In control group pathology and IgG staining revealed no abnormalities and expression of AQP4 was few.In trauma group light edema zone was visualized at 1 h,began widening,reached the peak at 12 h [(1.589 ±0.020)mm],and then began narrowing.There were significances in width of the edematous band at each time point except for the comparison at 24 h vs.48 h and 72 h vs.7 d (P ＜ 0.05).After trauma,vasogenic edema was found in edema zone at 1 h,intracellular edema was found at 6 h,both aggravated at 12 h and alleviated slightly at 24 h,and intracellular edema predominated at 48 h.IgG showed intensively positive staining at 1,12 and 48 h,and weak staining at 6 h,24 h,72 h and 7 d.After trauma,expression of AQP4 decreased at 1 h (0.659 ± 0.021),returned slightly at 6 h (1.257 ±0.058),peaked at 12 h (2.499 ±0.136),declined again at 24 h (2.267 ± 0.068),re-raised at 72 h (2.078 ± 0.065),and returned to the baseline at 7 d (1.280 ± 0.065).There were significant differences in level of AQP4 at each time point except for the comparison at6h vs.7 d,24 h vs.72 h and 24 h vs.72 h (P＜0.05).Conclusions In the early phase vasogenic edema characterized by BBB damage is significant within TP,which leads to decreased expression of AQP4.However,the subsequent up-regulation of AQP4 results in intracellular edema,which accelerate the spreading of TP.AQP4 may involve in body's defense reaction.