摘要目的:探讨高压氧协同靶向水通道蛋白-4(aquaporin 4，AQP-4)的RNA干扰(RNA interference，RNAi)技术对改善脑创伤(trauma brain injury，TBI)大鼠认知功能的作用，并探讨其机制。方法:将112只成年雄性SD大鼠按照随机数字表法分为对照组、AQP-4 RNAi组、高压氧组和联合治疗组，每组28只。采用液压打击法建立大鼠TBI模型，构建靶向AQP-4的RNAi质粒；大鼠按照分组给予相应方式的干预后，于术后7 d、21 d对大鼠进行改良神经功能缺损评分(modified neurological severity scores，mNSS评分)；术后21～25 d进行Morris水迷宫实验，记录大鼠目标象限停留时间百分比和每日逃避潜伏期；Evans蓝法测定血脑屏障通透性，干/湿比重法检测脑组织含水量；术后7 d用Western blot法检测AQP-4、半胱天冬酶-3 (caspase-3)、B淋巴细胞瘤-2基因(B-cell lymphoma-2，Bcl-2)、基质金属蛋白酶2(matrix metalloproteinase-2，MMP-2)和基质金属蛋白酶9(matrix metalloproteinase-9，MMP-9)蛋白表达水平；RT-PCR法检测脑组织AQP-4的mRNA表达水平；TUNEL法及Annexin V法检测脑细胞凋亡率。采用SPSS 23.0及Graphpad Prism 7.0进行数据分析，组间多样本行单因素方差分析，Morris结果采用重复测量方差分析，两两比较用LSD- t检验。 结果:mNSS评分结果显示，术后7 d，21 d，各组间mNSS评分差异有统计学意义( F＝4.89，7.59，均 P＝0.01)，各治疗组评分均低于对照组，以联合治疗组效果最理想(7 d： t＝3.98，-7.75；21 d： t＝47.82，7.94，均 P<0.05)。Morris水迷宫实验结果显示，大鼠的目标象限停留时间和逃避潜伏期的时间及组别交互作用均不显著( F＝1.83，8.42；均 P>0.05)，术后第24天和第25天，联合治疗组逃避潜伏期及目标象限停留时间百分比均好于其他各组(均 P<0.05)。Evans蓝染色显示，AQP-4 RNAi组、高压氧组、联合治疗组Evans蓝含量均较对照组低(均 P<0.05)，联合治疗组最低( t＝6.19， P<0.05)。干湿比重法结果显示，脑组织含水量以联合治疗组[(68.15±1.52)% ]最低( P<0.05)，AQP-4 RNAi组[(76.71±1.06)% ]低于高压氧组[(80.23±1.43)%]( t＝4.38， P<0.05)。Western blot结果显示，联合治疗组AQP-4、Caspase-3、MMP-2，MMP-9蛋白表达明显低于其他组(均 P<0.05)，而Bcl-2表达增加( P<0.05)。RT-PCR结果(灰度值比)显示，AQP-4 RNAi组(0.61±0.21)、高压氧组(0.83±0.12)及联合治疗组(0.22±0.05)的AQP-4 mRNA水平与对照组(1.31±0.25)比，均差异有统计学意义( F＝175.05， P<0.05)，AQP-4 RNAi组优于高压氧组( t＝5.25， P<0.05)，以联合治疗组降低最明显( t＝58.94， P<0.05)。TUNEL及Annexin V法检测结果显示，各治疗组较对照组均有效抑制神经细胞凋亡，尤以联合治疗组最为明显( P<0.01)。 结论:靶向AQP-4 RNAi技术联合高压氧可有效促进认知功能损害的恢复，其机制可能与保护血脑屏障完整性、减轻TBI后脑水肿并抑制神经细胞凋亡有关。

abstractsObjective:To investigate the effect of hyperbaric oxygen combined with RNA interference (RNAi) technology targeting aquaporin-4 (AQP-4) on improving cognitive function in rats with traumatic brain injury (TBI), and to explore its mechanism.Methods:Totally 112 adult male SD rats were randomly divided into four groups: control group, hyperbaric oxygen(HBO) group, AQP-4 RNAi group and combined treatment group, with 28 rats in each group.The TBI model of rat was established by hydraulic percussion and siRNA targeting aquaporin 4 was constructed. Rats were given corresponding intervention according to their groups.Then the modified neurological severity scores(mNSS)was evaluated on the 7th day and 21th day after operation. Morris water maze test was carried out from the 21st day to 25th day after operation and the percentage of target quadrant and daily escape latency were recorded.The changes of the brain permeability of blood-brain barrier and moisture in brain tissues were measured by Evans blue fluorometry and a wet-dry-weighing technique respectively. The protein expression levels of AQP-4, Caspase-3, Bcl-2, MMP-2 and MMP-9 were detected by Western blot method. The mRNA expression of AQP-4 in TBI brain tissue was measured by RT-PCR method, and the apoptosis rate of TBI brain cells was detected by TUNEL and AnnexinV methods on the 7th day after operation. SPSS 23.0 and Graphpad Prism 7.0 softwares were used for data analysis.One-way ANOVA was used for inter group comparison.Repeated measurement ANOVA was used for Morris results, and the LSD- t test was used for pairwise comparisons. Results:The results of mNSS showed that there were significant differences among the groups on the 7th day and 21st day after operation ( F=4.89, 7.59, both P<0.05). The scores of each treatment group were lower than that of the control group, and the effect of the combined treatment group was the best (7th day: t=3.98, -7.75, both P<0.05; 21st day: t=47.82, 7.94, both P<0.05). The results of Morris water maze test showed that the time and group interaction of rats in the target quadrant residence time and escape latency were not statistically significant( F=1.83, 8.42, both P>0.05). The escape latency and the percentage of stay in the target quadrant in the combined treatment group were better than those in other groups on the 24th and 25th day after operation (all P<0.05). Evans blue staining showed that the contents of Evans blue in AQP-4 RNAi group, hyperbaric oxygen group and combined treatment group were lower than that in the control group(all P<0.05), and that in the combined treatment group was the lowest( t=6.19, P<0.05). The results of dry-wet specific gravity method showed that the water content of brain tissue in the combined treatment group((68.15±1.52)%) was the lowest, and that in the AQP-4 RNAi group((76.71±1.06)%) was lower than that in the HBO group ((80.23±1.43)%)( t=4.38, P<0.05). The results of Western blot showed that the protein levels of AQP-4, Caspase-3, MMP-2 and MMP-9 in the combined treatment group were significantly lower than those in other groups(all P<0.05), while the expression of Bcl-2 was increased in the combined treatment group( P<0.05). RT-PCR results (gray value ratio) showed that AQP-4 mRNA levels in AQP-4 RNAi group(0.61±0.21), HBO group (0.83±0.12), combined treatment group(0.22±0.05) and CON group (1.31 ± 0.25) were significantly different( F=175.05, P<0.05), while the AQP-4 mRNA levels decreased in AQP-4 RNAi group which was better than that in hyperbaric oxygen group ( t=5.25, P<0.05). The decrease was the most obvious in the combined treatment group ( t=58.94, P<0.05). The results of TUNEL and AnnexinV showed that the treatment groups were more effective than the control group in inhibiting neuronal apoptosis, especially in the combined treatment group ( P<0.01). Conclusion:The combination of targeted AQP-4 RNAi and hyperbaric oxgen can effectively promote the recovery of neurological and cognitive function, and the mechanism may be related to protecting the integrity of blood-brain barrier, alleviating brain edema and inhibiting apoptosis of nerve cells after TBI.