水通道结合膜蛋白-4在大鼠缺血性脑水肿中的表达变化

目的：探讨脑水肿与水通道结合膜蛋白-4(AQP4)表达间的变化关系。方法：阻塞大脑中动脉(MCAO)，制作缺血性脑水肿模型，用干湿重法测定不同程度脑水肿状况下梗塞侧脑组织的含水量，用免疫组化及图像分析法观察AQP4阳性细胞数量及面积的变化。结果：MCAO 6h后，脑组织中水份开始增加，同时梗塞区部分组织深染，细胞肿大，梗塞区周围见阳性细胞开始增多。随梗塞时间延长，脑水肿加重，AQP4在整个梗塞区的表达增强，梗塞区周围阳性细胞数量递增。MCAO后在松果体血管周围及腺细胞间，以及最后区血管周围和一些阳性细胞染色增强。结论：AQP4与脑水肿的形成有关，并可能与AVP等神经内分泌活动有关。     

水通道蛋白-4与脑水肿关系研究进展

脑水肿是指脑组织内的异常水分潴留，使脑体积增大，是多种疾病伴发的一种病理状态。脑水肿的非手术治疗的方法有渗透性利尿、高张盐水，亚低温治疗等，尚没有针对脑水肿分子机制的有效治疗。水通道蛋白（AQP）是膜水通道蛋白家族，为调节跨细胞水平衡的选择性孔道，迄今在哺乳动物中已发现13种水通道蛋白（AQPO-AQPl2）^[1]。     

水通道蛋白-4在大鼠甲状腺中的表达

目的:观察水通道蛋白-4(AQP4)在甲状腺滤泡细胞的表达和分布特点,为研究甲状腺内分泌及调节机制提供形态学基础。方法:利用免疫组织化学、免疫荧光组织化学和原位杂交组织化学技术,检测大鼠AQP4及其mRNA在甲状腺滤泡上皮细胞的表达。结果:免疫组织化学和免疫荧光组织化学显示,AQP4在甲状腺滤泡上皮细胞膜上有表达,而在上皮细胞基底面和管腔面表达更为明显;原位杂交组织化学显示AQP4 mRNA在上皮细胞中表达明显。结论:AQP4在甲状腺的表达和分布特点,提示其参与了甲状腺素的合成和分泌过程中渗透压的精细调节作用。     

水通道蛋白4在大鼠轻度脑外伤后脑水肿形成中的作用

目的:通过研究大鼠脑外伤后,血脑屏障(BBB)通透性的改变和水通道蛋白4(AQP4)的表达变化,探讨其在脑外伤后脑水肿的形成、发展及转归中的作用,为临床治疗脑水肿提供依据.方法:采用伊文蓝测定法、免疫荧光双标显色、RT-PCR、干湿重法,分别检测BBB损伤程度,AQP4的表达,双侧大脑皮质、海马AQP4 mRNA的含量变化和脑含水量.结果:伤侧大脑BBB损伤于脑外伤后1～24 h明显,以1 h为甚,之后逐渐减轻;对侧则于伤后6～48 h损伤明显.免疫荧光双标和RT-PCR结果基本一致,双侧皮质AQP4及其mRNA于3 h增高,随后先降低再升高,至48～72 h达峰值;双侧海马几乎于各时段均呈显著降低.双侧皮质、海马含水量均于6 h显著增加,并达峰值,之后先略有下降后再次增加,至48～72 h达次高峰.结论:脑外伤早期,AQP参与了细胞外水肿的清除,其表达的下调和BBB的损伤,导致细胞外水肿形成.脑外伤继发损伤期,AQP4参与了细胞外水肿的清除和细胞内水肿的形成.     

水通道蛋白-4在大鼠睾丸和附睾中的表达

目的 观察水通道蛋白-4（AQP4）在雄性大鼠睾丸和附睾的表达及分布特点,为探讨水通道蛋白在睾丸和附睾中的作用提供形态学基础。方法 采用免疫组织化学的方法,检测AQP4在睾丸和附睾的表达分布。结果 AQP4在睾丸中表达于各级生精细胞、支持细胞以及间质细胞中;在附睾管内表达于柱状上皮细胞,且腔面表达更明显。结论 AQP4可能参与了精子的生成及成熟过程,在激素的分泌调节中发挥作用。     

水通道蛋白4在大鼠淋巴性脑水肿中的作用

 目的：研究水通道蛋白4（AQP4）在淋巴性脑水肿（LBE）形成和消散过程中的作用。方法：将大鼠随机分为假手术组和LBE组。采用结扎双侧颈部淋巴管并摘除淋巴结的方法,制作LBE模型。干湿重法检测大鼠大脑皮质含水量,应用免疫荧光组织化学方法及免疫印迹检测在颈淋巴引流阻滞后不同时点AQP4表达的变化情况,并对AQP4表达与脑含水量作相关分析。结果：与假手术组相比,LBE组大鼠脑含水量、AQP4免疫荧光表达阳性细胞数、强度及AQP4蛋白表达在术后3 d均见升高（P<0.05）,7 d升至高峰（P<0.01）,后逐渐降低,且AQP4蛋白表达与脑含水量呈正相关关系（r=0.8024,P<0.05）。结论：AQP4在大鼠LBE的形成和消散过程中起到了重要的作用。     

水通道蛋白4在大鼠脑垂体中的表达

目的：研究水通道蛋白4(AQP4)及其mRNA在脑垂体中的表达,探讨其在脑垂体激素分泌过程中的作用。方法：应用免疫组织化学和原位杂交技术,观察成年Wistar大鼠脑垂体中AQP4及其mRNA的正常分布。结果：AQP4及其mRNA在成年大鼠神经垂体的垂体细胞上表达呈阳性,分布在毛细血管窦周围的垂体细胞表达尤为强烈。腺垂体的所有细胞均有AQP4的表达,胞质中AQP4 mRNA表达呈阳性。中间叶所有细胞AQP4及其mRNA的表达呈弱阳性,其中滤泡星形细胞表达较内分泌细胞强烈。结论：AQP4广泛分布于脑垂体的各种组织细胞表面,可能在垂体激素的正常分泌过程中起重要的调节作用。     

水通道蛋白-2、4在小鼠肾发育过程中的表达

目的观察水通道蛋白-2（AQP-2）和水通道蛋白-4（AQP-4）在小鼠肾脏发育过程中的表达位置,探讨其与肾脏发生发育的关系及作用。方法免疫组织化学SABC法染色和体视学半定量检测AQP-2、AQP-4的表达。结果AQP-2在胚龄17d的胎鼠可以明确检测到,其表达部位为集合管主细胞的管腔膜和胞浆内。体视学测量发现,从胚龄17d开始表达到生后1d的小鼠其管腔膜的面密度值逐渐增加,此后面密度值基本上没有变化。AQP-4在胚龄14d的胎鼠可见到微弱的表达,随着胚龄的增长其表达逐渐增加,到生后1d达到最大水平,以后随着13龄的增加表达量无明显变化,并且在每一个时期的表达量都远远小于AQP-2的表达量。AQP-4的表达部位为集合管的侧基底细胞膜。结论推测AQP-2对小鼠出生后肾脏水平衡的调节作用比较重要,而AQP-4对出生前水平衡的调节作用比较重要。     

水通道蛋白-4在实验性脊髓损伤大鼠的表达

为了观察大鼠脊髓损伤后水通道蛋白4(AQP 4)的表达和对后肢功能的影响,本实验建立Allen脊髓损伤动物模型,于术后1、3、7、14和21d分别对大鼠进行了BBB评分检查后肢功能,处死动物后应用免疫组织化学技术检测脊髓组织内AQP 4的表达,用图像分析仪对脊髓损伤后神经组织的AQP 4的变化进行了定量分析。结果表明:脊髓损伤后第1d,在脊髓损伤组受损伤脊髓灰质和白质中均可见到AQP 4的表达明显增加;第3d时均达到高峰。在第7、14、和21d,AQP 4的表达与对照组均有显著性差异(P<0. 01)。本研究结果提示:脊髓损伤后大鼠脊髓组织中AQP 4的表达显著增加。     

Ghrelin对脑缺血再灌注大鼠脑水肿和水通道蛋白4表达的影响

 目的： 探讨ghrelin对脑缺血再灌注大鼠脑水肿、血脑屏障通透性及水通道蛋白4（AQP4）表达的影响。方法： 成年SD雄性大鼠随机分为3组:sham组、大脑中动脉阻塞（MCAO）组和ghrelin处理组。采用线栓法复制MCAO模型（缺血2 h,再灌注22 h）。Ghrelin组大鼠于再灌开始时经股静脉注射ghrelin 10 nmol/kg。TTC染色观察脑梗死体积,神经功能评分判断脑功能障碍程度,分别以体积计算和干湿重法检测脑肿胀程度和脑含水量的变化,收集脑血管外伊文思蓝(EB)来评估血脑屏障的破坏程度,免疫组化和Western blotting检测AQP4的表达变化。结果： 与MCAO组比较,ghrelin处理组的脑梗死体积较小（P<0.01）,神经功能评分较低（P<0.01）,脑组织中的EB渗出量较少（P<0.01）。Ghrelin处理组大鼠的脑肿胀体积、脑含水量和AQP4表达明显低于MCAO组（P<0.05）。结论： Ghrelin减轻大鼠脑缺血/再灌注损伤,减轻脑水肿和血脑屏障的破坏,抑制脑组织中AQP4的表达。AQP4在ghrelin的脑保护机制中可能发挥重要作用。     

大鼠缺氧缺血脑组织AQP-4蛋白和AQP-4mRNA表达的研究

目的探讨sD大鼠缺氧缺血过程中脑组织水通道蛋白_4（aquaporin-4,AQP-4）和AQP-4mRNA的表达情况及意义。方法健康雄性sD大鼠60只,分为缺氧缺血性脑损伤（HIBD）组和对照组。HIBD组经右侧颈总动脉结扎后建立模型,对照组仅行假手术,不结扎颈总动脉缺氧。HIBD组和对照组于模型制成后0h、6h、1d．2d和3d分别处死动物,对两组动物脑组织进行病理学观察,并检测脑组织中AQP-4蛋白和AQP-4mRNA表达。结果HIBD组在模型建立后6h、1d,2d和3d均出现脑水肿并发生组织病学改变,随时间延长病理改变加重。与对照组比较,HIBD组脑组织AQP-4蛋白和AQP-4mRNA表达从HIBD后6h即开始下降,2d内下降至最低,3d出现恢复。结论AQP-4可能参与了大鼠脑内渗透平衡的维持,AQP-4表达下降可能与HIBD脑组织水肿和病理学变化的发生发展相关。     

CART肽抑制缺血再灌注小鼠脑组织水通道蛋白4表达并减轻脑水肿

目的:研究可卡因及苯丙胺调节转录物(CART)肽对小鼠脑缺血再灌注急性期脑水肿的作用,并探讨其作用机制。方法:清洁级雄性ICR小鼠随机分为假手术(sham)组、大脑中动脉栓塞(MCAO)组和CART组,复制小鼠MCAO模型以模拟局灶性脑缺血再灌注损伤病理过程,TTC染色法计算脑梗死体积及脑水肿体积,干湿重法测定脑组织中水含量,通过检测伊文思蓝含量判断血脑屏障(BBB)的完整程度,免疫荧光和Western blot观察脑组织水通道蛋白4(AQP-4)的表达变化。结果:小鼠MCAO后24 h,CART肽处理组小鼠脑梗死体积和脑水肿体积均明显小于MCAO组(P0.01),脑组织水含量亦明显低于MCAO组(P0.01)。伊文思蓝测定表明,CART肽能够有效维持血脑屏障的完整性。免疫荧光和Western blot结果显示,MCAO小鼠脑组织中AQP-4表达明显升高,而CART处理明显抑制脑缺血再灌注诱导的AQP-4表达(P0.05)。结论:CART肽可减轻脑缺血再灌注损伤小鼠急性期脑水肿,维持血脑屏障完整性,其作用机制可能与抑制脑组织AQP-4表达水平密切相关。     

Hypertonic saline ameliorates cerebral edema through downregulation of aquaporin-4 expression in the astrocytes

Osmotherapy with 10% hypertonic saline (HS) alleviates cerebral edema through osmotic force. Aquaporin-4 (AQP4) has been reported to be implicated in the pathogenesis of cerebral edema resulting from a variety of brain injury. This study aimed to determine if 10% hypertonic saline ameliorates cerebral edema through downregulation of AQP4 expression in the perivascular astrocytes in the ischemic cerebral edema. Adult male Sprague–Dawley (SD) rats were subjected to permanent right-sided middle cerebral artery occlusion (MCAO) and treated with a continuous i.v. infusion of 10% HS. Brain water content (BWC) analyzed by wet-to-dry ratios in the ischemic hemisphere of SD rats was attenuated after 10% HS treatment. This was coupled with the reduction of neuronal apoptosis in the peri-ischemic brain tissue. Concomitantly, downregulated expression of AQP4 in the perivascular astrocytes after 10% HS treatment was observed. Our results suggest that in addition to its osmotic force, 10% HS exerts anti-edema effects possibly through downregulation of AQP4 expression in the perivascular astrocytes. The reduction of brain edema after 10% HS administration can prevent ischemic brain damage.     

Increased brain edema in aqp4-null mice in an experimental model of subarachnoid hemorrhage

We investigated the role of the glial water channel protein aquaporin-4 in brain edema in a mouse model of subarachnoid hemorrhage in which 30 μl of blood was injected into the basal cisterns. Brain water content, intracranial pressure and neurological score were compared in wildtype and aquaporin-4 null mice. We also measured blood-brain barrier permeability, and the osmotic permeability of the glia limitans, one of the routes of edema elimination. Wildtype and aquaporin-4 null mice had comparable baseline brain water content, intracranial pressure and neurological score. At 6 h after blood injection, aquaporin-4 null mice developed more brain swelling than wildtype mice. Brain water content increased by 1.5±0.1% vs. 0.5±0.2% (Mean±Standard Error, P<0.0005) and intracranial pressure by 36±5 vs. 21±3 mm Hg (P<0.05) above pre-injection baseline, and neurological score was worse at 18.0 vs. 24.5 (median, P<0.05), respectively. Although subarachnoid hemorrhage produced comparable increases in blood–brain barrier permeability in wildtype and aquaporin-4 null mice, aquaporin-4 null mice had a twofold reduction in glia limitans osmotic permeability. We conclude that aquaporin-4 null mice manifest increased brain edema following subarachnoid hemorrhage as a consequence of reduced elimination of excess brain water.     

Brain edema and protein expression of c-Fos and c-Jun in the brain after diffused brain injury

Objective: To investigate brain edema and protein expression of c-Fos and c-Jun in brain after diffuse brain injury, and to investigate the pathological change after brain injury, which may provide evidence for the clinical treatment of diffused brain injury. Methods: Marmarou method was used to establish the diffuse brain injury in rats. Results: After diffused brain injury, brain water content increased at 1 h, reached the peak at 1 d and remained at a high level at 7 d when compared with control group. One day after injury, diffuse subarachnoid hemorrhage was observed in the brain. HE staining showed vascular swelling and bleeding at the cortex and corpus callosum at 1 d. β-APP expression was found at the brainstem, hippocampus, thalamus, corpus callosum and periventricular regions. Pathological examination of ultrathin sections showed evidence edema and fracture of axons at 3 d after brain injury. The brain injury caused severe cerebral ischemia. The c-Fos and c-Jun expression increased at 1 h. The c-Fos expression peaked at 3 h (P < 0.05), then reduced, reached a maximal level again at 3 d (P < 0.05), and reduced significantly at 7 d but remained at a higher level when compared with control group (P < 0.05). The number of c-Jun positive cells peaked at 6 h (P < 0.05), then reduced, reached a maximal level again at 3 d and reduced markedly but still remained at a higher level when compared with control group (P < 0.05). Conclusion: After diffuse brain injury, brain water content and c-Fos/c-Jun expression change over time.     

Effects of dexamethasone on aquaporin-4 expression in brain tissue of rat with bacterial meningitis

Aquaporin-4 (AQP4) is the most popular water channel protein expressed in brain tissue and plays a very important role in regulating the water balance in and outside of brain parenchyma. To investigate the expression of aquaporin-4 in the rat brain tissue after dexamethasone therapy of meningitis induced by Streptococcus pneumonia, total 40 of 3-week old Sprague-Dawley rats were divided into infection group (n=30) and normal control group (n=10). The meningitis groups were infected with 1×10⁷ cfu/ml of Streptococcus pneumoniae and then randomized into no treatment (untreated group, n=10), treatment with ceftriaxone (CTRX group, n=10) and treatment with dexamethasone combined ceftriaxone (CTRX + DEXA group, n=10). The normal control group was established by using saline. The rats were euthanized when they reached terminal illness or five days after infection, followed by detection of AQP4 through using immunohistochemistry and Western blot methods. Data has showed that expression of AQP4 in model group remained higher than the control and treatment group (P<0.05). AQP4 expression in CTRX + DEXA group was lower than that in CTRX group (P<0.05). There was no statistical difference between CTRX + DEXA group and the control group (P>0.05). These data suggested that Dexamethasone could down-regulate the expression of AQP4 in the brain tissue of rats with meningitis and provides evidence for the mechanism of protective effect of Dexamethasone on central neurosystem.     

水通道蛋白4和人星形胶质细胞瘤在体内增殖和瘤周水肿的相关性研究

目的：研究水通道蛋白4（aquaporin-4, AQP4）和人星形胶质细胞瘤在体内增殖和瘤周水肿的相关性。方法建立人星形胶质细胞瘤裸鼠模型; EdU法检测细胞增殖;免疫组织化学法检测肿瘤组织内CD34阳性细胞表达,检测肿瘤组织微血管密度;免疫印迹法测AQP4蛋白表达;以人脑正常星形胶质细胞为阴性对照。结果细胞皮下注射一周后可见肿瘤长出, EdU法检测肿瘤增殖能力随肿瘤恶性程度增加而增大,免疫组织化学检测提示高度恶性组较低度恶性组具备更高的微血管密度, AQP4蛋白表达随恶性程度增加而增加。结论水通道蛋白4的表达水平和人星形细胞瘤增殖和瘤周水肿程度密切相关。