水通道蛋白-4与缺血性脑水肿

脑水肿在脑缺血后的病理生理过程中起着重要的作用,与脑缺血后的致残率、致死率和神经功能的恢复密切相关。研究发现,水通道蛋白-4(AQP 4)仅对水分子有通透性,又在脑组织中广泛存在,可参与介导调节水分子的跨膜转运,关系着脑水肿发展进程,因此,已成为目前医学界研究的热点。本文就AQP 4的分子结构、分布、定位、调节机制、生理学作用以及与脑水肿的关系等方面作一综述。1 AQP 4的分子结构AQP 4基因位于18号染色体的q11.2与q12.1之间的接合处,由四个分别编码127、55、27、92位氨基酸的外显子组成,并被0.8、0.3和5.2kb的内含子分隔开[1]…     

水通道蛋白-4表达与脑水肿形成的关联性探讨

脑水肿是一种神经内外科十分常见的症状,目前,对于该病的形成还尚不完全了解,治疗方法有限,取得的效果也不同。水通道蛋白发现于1988年,是生物体内水分子通道的一种。水通道蛋白4属于水通道蛋白类型的一种,有研究结果显示,水通道蛋白-4密切关系着着脑水肿的形成和预后,通过对水通道蛋白-4的调节,能够对脑水肿的形成和预后产生影响,此外,水通道蛋白-4还可能具有其他作用。所以,观察与探讨水通道蛋白-4表达与脑水肿形成的关联性对预防脑水肿的产生和治疗很有帮助,此外,还可深入了解生物体内的水的代谢。     

AG490对大鼠脑液压冲击伤后脑水肿及水通道蛋白4表达的影响

目的研究AG490对大鼠脑液压冲击伤后继发性脑水肿及水通道蛋白4(AQP-4)表达的影响。方法取健康成年雄性SD大鼠104只,按照随机数字表法分为假手术组8只,对照组48只,AG490组48只,对照组及AG490组随机各分为6个亚组分别对应伤后各时间点3h、6h、12h、24h、48h、72h。对照组及AG490组给予液压冲击打击,制作大脑损伤模型;假手术组仅给予颅骨钻孔术不给予液压冲击。AG490组于伤后1小时按照5mg/kg给予腹腔注射AG490,对照组接受等量生理盐水。干湿重法测定脑组织含水量,免疫组织化学法测定脑组织AQP-4蛋白的表达,HE染色后光镜下观察细胞形态学改变。结果 (1)和假手术组比,对照组及AG490组脑组织含水量均升高(P<0.05)。AG490组各时间段均比对照组脑组织含水量少(P<0.05)。(2)AQP-4表达阳性细胞镜下呈棕黄色空泡状。AG490组各时间亚组AQP-4表达水平均较对照组减低(P<0.05)。(3)光镜下见AG490组各时间点均较对照组病理损伤轻。结论脑损伤后急性期应用AG490可以明显减轻创伤后脑水肿,其作用可能与抑制AQP-4在损伤脑组织中的表达有关。     

水通道蛋白4mRNA在大鼠蛛网膜下腔出血后脑水肿中的表达及尼莫地平对其表达的影响

目的：研究大鼠蛛网膜下腔出血后脑组织AQP4mRNA的表达及脑含水量的变化以及应用尼莫地平对AQP4mRNA表达的影响。方法：健康成年大鼠60只,随机分为对照组、假手术组、SAH组、尼莫地平组,建立蛛网膜下腔出血模型,分别在6h、1d、3d、5d、7d个时间点断头取脑,测定脑含水量,并用RT-PCR法检测AQP4mRNA表达。结果：SAH组脑含水量及脑组织内AQP4在6h后即增加,随时相递增,3d达到高峰,较假手术组及尼莫地平组明显增高（P＜0.05）。结论：大鼠蛛网膜下腔出血后脑水肿的程度与AQP4的表达成正比,这表明AQP4在蛛网膜下腔出血性脑水肿的病理生理中起着非常重要的作用。尼莫地平可以下调AQP4mRNA的表达,从而减轻脑水肿的程度。     

大鼠颅脑损伤急性期水通道蛋白4表达变化的研究

目的探讨水通道蛋白4(AQP4)在大鼠重型颅脑损伤时的表达变化及其与脑水肿间的关系。方法98只成年雄性Wistar大鼠,随机分为对照组及实验组(伤后0.5、2、6、12、24、48、72 h共7组,对照组不打击)。制作大鼠液压冲击颅脑损伤模型,分别于伤后0.5、2、6、12、24、48、72 h采用干湿比重法测脑组织含水量,半定量反转录聚合酶链反应(RT-PCR)检测脑组织AQP4 mRNA表达及其变化。结果脑组织AQP4 mRNA在伤后0.5 h开始表达上调,2、6、12 h依次增高,24 h达到峰值(P<0.05),72 h时仍维持较高水平。脑组织含水量与AQP4 mRNA表达变化一致。经相关性分析,AQP4 mRNA的表达与脑组织含水量呈正相关(r=0.095,P<0.05)。结论重型脑损伤急性期,AQP4 mRNA表达变化与颅脑损伤后脑水肿的形成和发展密切相关。AQP4可能参与重型脑损伤后脑水肿的形成并起重要作用。     

水通道蛋白-4研究进展

1988年，Agre等分离红细胞Rh蛋白时偶然发现一种分子量为28KD的水通道结合膜蛋白(CHIP 28)，于1991年完成其cDNA克隆，并将其成功转染非州爪蟾卵母细胞，结果显示其具有选择性水通透的功能。至此．很多学者都将目光投向这一类只允许水通过的选择性通道蛋白即水通道蛋白(aquaporin，AQP)。到目前为止．已发现的水通道蛋白共有10种，即AQPO至AQP9。     

水通道蛋白4的研究进展

AQP家族是近几年来逐渐被发现并认识的一类水特异性膜内在蛋白,已有200多种水通道广泛分布于动物植物微生物中,在哺乳动物组织中已发现13种水通道蛋白（AQP0-AQP12）。迄今已在脑内已发现7种AQP,别是AQP1,3,4,5,8,9,11,其中水通道蛋白-4（AQP4）为主要在脑组织中表达的水通道蛋白。它参与了脑缺血、脑水肿等病理生理过程,调节水通道蛋白表达水平可能为脑缺血、脑水肿等的治疗提供新的途径。     

孕酮对缺氧缺血性脑损伤新生大鼠血脑屏障通透性及脑水肿的影响

目的研究孕酮(PROG)对缺氧缺血性脑损伤(HIBD)新生大鼠血脑屏障(BBB)通透性和脑水肿的作用,并进一步探讨其潜在的机制。方法 7 d龄SD大鼠96只,随机分成4组:正常组、假手术组、缺氧缺血(HI)组和PROG组。建立HIBD动物模型,HI后24 h,伊文思蓝示踪剂检测BBB;干/湿法测定脑含水量;免疫组织化学法观察大脑皮质水孔通道蛋白4(AQP4)表达。结果正常组和假手术组BBB通透性、脑含水量和脑皮质AQP4的表达差异无显著性(P>0.05);HI组BBB通透性、脑含水量和脑皮质AQP4的表达明显高于假手术组(P<0.01);PROG组BBB通透性、脑含水量和脑皮质AQP4的表达明显低于HI组(P<0.05)。结论 PROG通过减轻BBB破坏和脑水肿对HIBD新生大鼠起脑保护作用,PROG的脑保护作用可能与下调新生大鼠脑皮质AQP4的表达有关。     

尼莫同对大鼠缺血性脑水肿脑组织内AQP4 mRNA表达的影响

目的研究大鼠缺血性脑水肿脑组织内AQP_4 mRNA表达及脑水含量的变化,以及尼莫同的干预机制。方法健康Wistar大鼠75只,随机分为假手术组、手术组、尼莫同组,建立大脑中动脉闭塞(MCAO)模型,分别在6h、1d、3d、5d、7d5个时间点将大鼠麻醉后断头取脑,测定脑水含量,并用RT-PCR法测定AQP_4 mRNA表达。结果手术组大鼠脑水含量及脑组织内AQP_4 mRNA表达在6h后开始升高,3d后达到高峰,较假手术组和尼莫同组明显增高(P<0.05)。结论缺血性脑水肿脑组织内AQP_4 mRNA呈高表达,提示AQP4与脑水肿形成有关,钙离子拮抗剂尼莫同可以降低脑组织内AQP_4 mRNA表达,从而减轻脑水肿程度。     

黄体酮对颅脑损伤大鼠脑组织含水量及水通道蛋白-4表达的影响

目的:探讨黄体酮对脑外伤模型大鼠脑组织含水量、水通道蛋白-4(AQP-4)表达的影响机制.方法:SD雄性大鼠165只,随机分为假手术组(55只)、模型组(55只)和黄体酮组(55只),用Freeney法造成大鼠脑挫裂伤模型,干湿重法测定脑组织含水量,并采用免疫组化方法检测脑组织AQP-4蛋白的表达.结果:模型组大鼠伤后各时间点伤侧脑组织含水量、伤灶周围AQP-4蛋白表达水平均明显高于假手术组(均P<0.05);黄体酮治疗组各时间点脑组织含水量、AQP-4表达水平均较模型组降低(P<0.05).结论:黄体酮可以明显减轻创伤后脑水肿,其作用可能与抑制AQP-4在损伤脑组织中的表达有关.     

乙酰唑胺对内毒素血症鼠胃黏膜水通道蛋白4表达的影响

目的探讨乙酰唑胺对内毒素血症鼠胃黏膜水通道蛋白4（AQP4）表达的影响及意义。方法健康SD大鼠30只,随机分成三组：对照组、内毒素血症组（EDT组）和乙酰唑胺作用组（ATL组）,每组10只,免疫组织化学法检测各组大鼠胃黏膜中AQP4的表达,并同时放免法测定其血清肿瘤坏死因子-α（TNF-α）和白细胞介素-1β（IL-1β）水平。结果EDT组AQP4蛋白表达及血清TNF-α、IL-1β水平较对照组明显增加（均P〈0．01）。乙酰唑胺作用后,A1L组的胃黏膜上皮水通道AQP4蛋白表达及血清TNF—α、IL-1β水平均明显低于EDT组（均P〈0．01）。结论AQP4表达的增加和血清TNF-α、IL-1β水平增高参与了内毒素血症大鼠急性胃黏膜组织的损害。乙酰唑胺可下调胃黏膜上皮水通道蛋白AQP4的表达并降低血清TNF—α,IL-1β水平,减轻内毒素对胃黏膜上皮组织造成的损害,保护胃黏膜组织。     

Effects of progesterone on some brain neurotransmitters in intact rats.

Effects of progesterone on four neurotransmitters (viz, noradrenaline, 5-HT, dopamine and histamine) of brain were seen in rats with intact ovaries. It was found that progesterone lowers the noradrenaline concentration in medulla, pons, midbrain, hypothalamus, thalami and pituitary, uniformly, when the rats were killed within 4 hours of progesterone injection. At longer intervals (48 hrs) effects of progesterone were seen when progesterone in heavy dose was administered to rats pretreated with estrogen. It is likely that one of the modes of action of the oral contraceptives may be the reduction of noradrenaline content in selected areas of brain, by progesterone. It is also suggested, therapeutic usage of progesterone carries the risk of development of depression in the user.     

凉血通瘀方对大鼠脑出血脑组织含水量及AQP-4表达的影响

目的探讨凉血通瘀方对脑出血后脑水肿组织含水量及AQP-4表达的影响。方法采用自体尾状核内注射方法制备大鼠脑出血模型。大鼠分为凉血通瘀方治疗组、脑出血模型组和假手术组。凉血通瘀方治疗组采用凉血通瘀方灌胃,其余组采用生理盐水灌胃。分别观察脑出血后12 h、1 d、2 d、3 d、5 d神经功能缺损评分、脑组织含水量。免疫荧光法及聚合酶链反应监测脑水肿组织AQP-4蛋白、AQP-4 mRNA表达水平。结果凉血通瘀方治疗组和脑出血组在不同时间段内神经功能缺损均高于对照组,其脑组织含水量也高于对照组(P<0.05)。与脑出血组相比较,凉血通瘀方治疗组在脑出血后2、3、5 d时,AQP-4表达显著降低,在3、5 d后,大鼠AQP-4 mRNA表达显著降低。结论凉血通瘀方能够降低脑水肿组织AQP-4的表达,从而减轻脑水肿。     

Methylene blue ameliorates brain edema in rats with experimental ischemic stroke via inhibiting aquaporin 4 expression

Brain edema is a common and serious complication of ischemic stroke with limited effective treatment.We previously reported that methylene blue(MB)attenuated ischemic brain edema in rats,but the underlying mechanisms remained unknown.Aquaporin 4(AQP4)in astrocytes plays a key role in brain edema.We also found that extracellular signal-regulated kinase 1/2(ERK1/2)activation was involved in the regulation of AQP4 expression in astrocytes.In the present study,we investigated whether AQP4 and ERK1/2 were involved in the protective effect of MB against cerebral edema.Rats were subjected to transient middle cerebral artery occlusion(tMCAO),MB(3 mg/kg,for 30 min)was infused intravenously through the tail vein started immediately after reperfusion and again at 3 h after ischemia(1.5 mg/kg,for 15 min).Brain edema was determined by MRI at 0.5,2.5,and 48 h after tMCAO.The decreases of apparent diffusion coefficient(ADC)values on diffusion-weighted MRI indicated cytotoxic brain edema,whereas the increase of T2 MRI values reflected vasogenic brain edema.We found that MB infusion significantly ameliorated cytotoxic brain edema at 2.5 and 48 h after tMCAO and decreased vasogenic brain edema at 48 h after tMCAO.In addition,MB infusion blocked the AQP4 increases and ERK1/2 activation in the cerebral cortex in ischemic penumbra at 48 h after tMCAO.In a cell swelling model established in cultured rat astrocyte exposed to glutamate(1 mM),we consistently found that MB(10μM)attenuated cell swelling,AQP4 increases and ERK1/2 activation.Moreover,the ERK1/2 inhibitor U0126(10μM)had the similar effects as MB.These results demonstrate that MB improves brain edema and astrocyte swelling,which may be mediated by the inhibition of AQP4 expression via ERK1/2 pathway,suggesting that MB may be a potential choice for the treatment of brain edema.     

Increased expression of aquaporin-4 with methylmercury exposure in the brain of the common marmoset

The relationship between methylmercury (MeHg) exposure and aquaporin (AQP) expression in the brain is currently unknown. To investigate this, we used a common marmoset model of acute MeHg exposure to examine AQP1, AQP4 and AQP11 gene expression. MeHg (1.5 mg Hg/kg/day p.o.) was given to three marmosets for 14 days, followed by 14 days without. All treated marmosets showed slight akinesia before sacrifice. In the frontal lobe, occipital lobe and cerebellum, total mercury concentrations following MeHg administration were 26.7, 31.4, and 22.6 μg/g, respectively. Slight apoptosis was observed in the occipital lobe. Immunohistochemistry showed increased expression of glial fibrillary acidic protein, its mRNA and Iba1 with MeHg, indicating that neuronal injury activated astrocytes and microglia. There was no significant difference between control and MeHg-administered groups in AQP1 protein or AQP11 mRNA in the frontal lobe, occipital lobe or cerebellum. The ratio of AQP4 mRNA expression in MeHg-administered marmosets to the mean AQR4 expression in the controls (n = 3) were 1.3, 1.5 and 1.2, 1.7, 1.9 and 1.5, and 1.5, 1.6 and 1.2 for the frontal lobe, occipital lobe and cerebellum, respectively. Western blotting showed significantly increased AQP4 protein in the occipital lobe and cerebellum with MeHg administration, but no obvious up-regulation in the frontal lobe. Immunofluorescence analysis with double staining revealed low AQP4 expression in the cell body of reactive astrocytes in the MeHg-administered group. These results indicate that AQP4 expression might be stimulated by MeHg exposure in astrocytes in the occipital lobe and cerebellum, suggesting a role for AQP4 in MeHg neurotoxicity via astrocyte dysfunction.