β-七叶皂苷钠对大鼠局灶性脑缺血再灌注后AQP4蛋白表达的影响

目的探讨大鼠局灶性脑缺血再灌注脑组织缺血区AQP4蛋白的表达情况及β-七叶皂苷钠的治疗作用和可能机制。方法采用大鼠大脑中动脉闭塞法(MCAO)制作局灶性脑缺血再灌注模型。应用干-湿比重法、TTC染色、免疫组化SABC法分别测定脑含水量、脑梗死体积及水孔蛋白4(aquaporin4,AQP4)的表达。结果假手术组AQP4蛋白有轻微的表达,而模型组、治疗组缺血损伤后表达升高,脑含水量增高,梗死脑组织出现,给予β-七叶皂苷钠的治疗组AQP4蛋白的表达下降,脑含水量明显降低,脑梗死体积减少,且β-七叶皂苷钠中高剂量组明显优于低剂量组(P<0.05)。结论脑缺血再灌注脑组织缺血区AQP4蛋白表达的上调与脑水肿的发生发展与有密切的关系,而β-七叶皂苷钠有抑制脑水肿发生的作用。     

亚低温通过抑制AIF核转位改善大鼠颅脑损伤

目的 探讨亚低温对颅脑损伤（TBI）大鼠脑组织凋亡诱导因子（AIF）核转位的影响。方法 将36只成年雄性SD大鼠随机分为假手术组、TBI组、亚低温组，每组12只。采用控制性皮质撞击建立TBI模型，亚低温组大鼠给予亚低温处理。TBI后24 h，HE染色观察大鼠脑组织病理学变化；免疫组织化学方法检测大鼠脑组AIF的表达部位；免疫印迹法检测损伤脑组织线粒体和细胞核AIF、caspase-3的表达情况。结果 HE染色结果显示，TBI后，损伤侧脑组织可见沿灰白质界面的挫伤和出血，亚低温组挫伤和出血灶明显减轻。免疫印迹法检测结果显示，TBI后，损伤脑组织caspase-3表达量明显增加（P<0.01），细胞核AIF表达量明显增加（P<0.01），而线粒体AIF表达量明显降低（P<0.05）；亚低温组损伤脑组织caspase-3表达量明显下降（P<0.01），细胞核AIF表达量明显下降（P<0.01），而线粒体AIF表达量明显升高（P<0.05）。免疫组织化学染色结果显示，假手术组AIF位于大脑皮质和海马神经元细胞核外；TBI组后，损伤侧皮质及海马区AIF从线粒体转移至细胞核内的阳性细胞数量明显增多（P<0.01）；亚低温组损伤侧皮质及海马区AIF发生核内转移的阳性细胞数量减少（P<0.01）。结论 亚低温可能通过抑制AIF的核转位减轻颅脑损伤后神经细胞凋亡，从而起到神经保护作用。     

药物难治性癫痫患者脑内水通道蛋白-4的表达上调

目的研究水通道蛋白4(AQP4)在药物难治性癫痫脑组织中的表达。方法研究时间自2004年5月至2005年3月。采用逆转录聚合酶链式反应(RT-PCR)、免疫组织化学和免疫蛋白印迹(WESTERN BLOT)技术,分析比较18例药物难治性癫痫患者癫痫灶脑组织与20例正常对照脑组织标本AQP4的MRNA和蛋白的表达水平。结果药物难治性癫痫患者脑组织AQP4的MRNA和蛋白的表达均显著高于正常对照组(P<0．01)。结论 AQP4可能参与了药物难治性癫痫患者癫痫发作后的脑水肿的发生,是癫痫继发脑水肿的重要分子基础。     

RNA干扰AQP4对创伤性脑水肿血脑屏障的保护作用

目的探讨RNA干扰（RNAi）水通道蛋白4（AQP4）对创伤性脑水肿血脑屏障（BBB）的保护作用。方法雄性成年Wistar大鼠,随机分为假手术组、对照质粒组、单纯创伤组和创伤后RNAi组。参照Marmarou法制作创伤性脑损伤（TBI）模型。采用侧脑室注射途径给药,应用免疫组织化学观测AQP4、微血管内皮细胞紧密连接闭合小环蛋白（ZO-1）,原位杂交法观测AQP4mRNA,光电镜观察脑组织超微结构。结果RNAi质粒可有效减少AQP4在受损脑组织的表达;RNAi组在各检测时间点脑组织含水量和BBB透性均小于TBI组和对照质粒组（P〈0．05）;TBI后RNAi组ZO-1表达水平各时间点明显高于单纯创伤组和对照粒组（P〈0．05）。结论TBI后损伤区AQP4的表达变化趋势和脑水肿的发展变化趋势相一致（r=0．982,P〈0．01）;应用RNA干扰途径减少AQP4表达,可有效保护TBI后脑水肿BBB结构的破坏。     

低温治疗大鼠创伤性脑损伤对脑水肿及IL-1β的影响

目的研究低温治疗大鼠创伤性脑损伤后对脑水含量、Na^＋含量及白细胞介素-1β（IL-1β）的影响，以探讨低温的治疗作用及可能机制。方法采用Feeney打击模型，分别进行全身低温、全脑低温或局灶低温治疗，治疗结束后检测伤灶脑组织含水量、Na^＋含量、IL-1β含量、IL-1β蛋白表达及IL-1βmRNA表达。结果局灶低温组及全身低温组在脑水含量、Na^＋含量、IL-1β含量、IL-1β蛋白表达、IL-1βmRNA表达方面低于脑外伤模型组（P〈0．05），且局灶低温组低于全身低温组（P〈0．05）；而全脑低温组在上述方面高于脑外伤模型组（P〈0．05）。结论局灶低温及全身低温治疗能明显减轻脑水肿，且局灶低温效果更佳；全脑低温治疗加重脑水肿；其机制之一可能是通过抑制或促进炎性因子IL-1β表达而起作用。     

丁苯酞对局灶性脑梗死大鼠脑水肿及咬合蛋白表达的影响

目的探索丁苯酞对局灶性脑梗死大鼠脑水肿及咬合蛋白表达的影响。方法随机选取成年Sprague-Dawley雄性大鼠125只,分为对照组、模型组和丁苯酞组。丁苯酞组给予丁苯酞软胶囊灌胃。观察不同时间点大鼠脑水肿面积、脑组织形态学变化、脑组织含水量变化、梗死灶周围皮层咬合蛋白表达变化。结果与模型组相比,丁苯酞组脑水肿面积明显减少。脑组织含水量明显降低。咬合蛋白表达量明显增加。结论丁苯酞软胶囊可明显减少局灶性脑梗死大鼠脑水肿的形成,增加大脑皮层咬合蛋白的表达。     

乌司他丁预处理对小鼠颅脑损伤保护的初步研究

目的探讨乌司他丁(UTI)预处理对小鼠颅脑损伤早期的保护作用。方法 BALB/c小鼠44只,随机分为假手术组(SO组)、创伤性脑损伤组(TBI组)、乌司他丁预处理组(UTI组)和生理盐水对照组(Control组)。预处理组连续3 d给予UTI 300 000 U/(kg.d)腹腔注射。除SO组外,其余各组应用自由落体打击法建立创伤性脑损伤模型。采用干湿重法检测脑组织含水量,HE染色光镜下观察损伤皮质区形态变化,使用Western blot方法检测脑组织中水通道蛋白4(AQP4)表达。结果 UTI组颅脑损伤早期(24 h)脑组织含水量低于TBI组(P<0.05),其损伤皮质区神经元状态优于TBI组。同时,UTI组的AQP4蛋白表达水平低于TBI组,差异显著(P<0.05)。结论乌司他丁预处理减轻颅脑损伤早期脑水肿与其抑制AQP4蛋白表达有关。     

亚低温治疗对脑缺血大鼠AQP4基因表达及血脑屏障通透性的影响

目的 观察亚低温治疗对脑缺血大鼠AQP4表达和血脑屏障通透性的变化的影响,探讨亚低温减轻缺血性脑水肿的可能机制.方法 线栓法制作脑缺血大鼠模型,实验分常温组、亚低温组和假手术组,分别在缺血后6h、24h、48h、72h用干湿重法测脑组织含水量,荧光法检测血脑屏障通透性的改变,原位杂交检测AQP4的表达变化.结果 假手术组脑组织含水量、血脑屏障通透性、AQP4表达无变化.缺血组脑组织含水量和血脑屏障通透性增加,AQP4表达上调,缺血48～72h变化最显著.相同时间点常温组脑组织含水量和血脑屏障通透性增加、AQP4的表达上调比亚低温组明显,两组之间的差异具有统计学意义(P＜0.05).结论 亚低温条件下AQP4表达下调、血脑屏障通透性和脑水肿程度减轻.亚低温可能通过下调AQP4表达、减轻血脑屏障通透性,减轻缺血性脑水肿.     

中药补阳还五汤对脑出血大鼠脑组织水通道蛋白4表达的影响

目的探讨中药补阳还五汤对脑出血大鼠脑组织水通道蛋白4(AQP4)表达的影响。方法 55只雄性SD大鼠随机分为假手术组(5只)、脑出血模型组(25只)和补阳还五汤治疗组(25只)。采用自体血注入法制作右侧纹状体出血大鼠模型。假手术组不注入自体血。补阳还五汤治疗组于术前给予1 ml/100 g补阳还五汤浓缩液灌胃3 d,假手术组和脑出血模型组同期给予等量生理盐水替代。在相应时间点分别对大鼠进行神经功能缺损评分后处死大鼠。采用免疫组化法检测脑组织AQP4蛋白的表达,采用原位杂交法检测脑组织AQP4 mRNA的表达。结果补阳还五汤治疗组及脑出血模型组大鼠神经功能缺损评分明显高于假手术组(均P<0.05)。补阳还五汤治疗组大鼠术后3 d和7 d时神经功能缺损评分明显低于脑出血模型组(均P<0.05)。补阳还五汤治疗组及脑出血模型组大鼠脑组织AQP4蛋白和mRNA表达水平明显高于假手术组(均P<0.05)。补阳还五汤治疗组大鼠术后3 d和7 d时脑组织AQP4蛋白和mRNA表达水平明显低于脑出血模型组(均P<0.05)。各组大鼠均未见明显不良反应。结论补阳还五汤可抑制脑出血大鼠脑组织中AQP4的表达,并有助于其神经功能恢复。补阳还五汤治疗脑出血有效可能与其抑制AQP4的表达,减轻脑水肿有关。     

脑损伤后水通道蛋白4表达与血脑屏障通透性的关系

目的研究脑损伤后，水通道蛋白4（AQP4）的表达变化与血脑屏障（BBB）通透性之间的关系。方法健康成年Wistar大鼠，随机分成创伤性（TBI）组和假手术（SO）组。自由落体硬膜外撞击方法致重度脑创伤模型。于伤后4h、8h、12h、1d、3d、5d、7d取出大鼠脑组织，进行以下实验：①测创伤脑组织中伊文思蓝（EB）外渗的量，以EB外渗的量反应BBB通透性的变化；②免疫组化（IHC）和原位杂交（ISH）检测AQP4的表达变化。结果脑损伤后，BBB通透性增加，其增加有两个高峰，分别在TBI后12h和3d，后者尤为更明显。IHC和ISH显示，脑损伤后AQP4在脑组织中的表达逐渐上调，1d达高峰，持续至3d后下降，7d接近SO组水平。AQP4的表达变化与脑组织伊文思蓝（EB）含量的变化呈正相关（r=0．894，P〈0．05）。结论脑损伤后BBB通透性的增加与脑水肿的形成密切相关。TBI后BBB通透性增加，可能与AQP4表达上调有关，两者的变化影响TBI后脑水肿的发生、发展。     

盐酸纳美芬对大鼠颅脑损伤后脑水肿的影响

目的探讨盐酸纳美芬对大鼠颅脑损伤后脑水肿的影响。方法将54只Wistar大鼠按随机数字表法随机分为假手术组、颅脑损伤组及纳美芬治疗组。采用自由落体法建立大鼠颅脑损伤模型,分别于伤后6 h、1 d、3 d、7 d,采用干湿重法检测脑组织含水量,应用免疫组织化学法检测损伤脑组织中水通道蛋白4（AQP4）的表达。结果与假手术组比较,颅脑损伤组和纳美芬治疗组的脑组织含水量及AQP4水平明显升高（P〈0.05）;与颅脑损伤组相比,纳美芬治疗组脑组织含水量及AQP4表达水平明显降低（P〈0.05）。通过相关性分析发现,大鼠颅脑损伤后脑组织AQP4表达水平与脑含水量呈明显正相关性（r=0.676,P〈0.01）。结论盐酸纳美芬可能通过抑制AQP4表达,减轻脑水肿,发挥神经保护作用。     

亚低温对实验性脑出血后水通道蛋白4表达及脑水肿的影响

目的研究亚低温对脑出血后水通道蛋白4(AQP4)表达及脑水肿的影响,探讨亚低温对出血性脑水肿的作用机制。方法在大鼠苍白球注射胶原酶制作脑出血模型,用冰块降温及白炽灯照射加温的方法调节体温;应用免疫组化方法检测脑组织AQP4表达,采用干湿重法观察脑含水量的动态变化。结果脑出血模型大鼠病灶侧脑含水量、血肿周围AQP4的表达水平明显高于假手术组(均P<0.001);各个时间点亚低温组大鼠病灶侧脑含水量以及血肿周围AQP4的表达水平均明显低于对照组(P<0.05～0.01);AQP4表达水平与脑含水量呈正相关(r=0.977,P<0.001)。结论亚低温能明显减轻脑出血后脑水肿及AQP4的表达,亚低温可能通过抑制AQP4的表达而减轻脑水肿。     

Hypothermia in acute stroke--slow versus fast rewarming an experimental study in rats

The rewarming phase after therapeutic hypothermia in cerebral ischemia appears crucial as rapid rewarming may lead to rebound phenomena and enhance deleterious ischemic effects. We hypothesized that slow and controlled rewarming after moderate hypothermia is superior to fast rewarming in rats subjected to 90 min temporary middle cerebral artery occlusion (tMCAO). Two experiments were designed: (i) 34 rats were randomly assigned to either normothermic treatment, to hypothermia (33 degrees C) with rapid rewarming within 20 min, or to hypothermia with slow rewarming within 2 h after 4 h of hypothermia starting 2 h after tMCAO. Infarct size, neuroscore, myeloperoxidase and aquaporin 4 (AQP4) positive cells were assessed on day 5 after tMCAO. (ii) In 15 rats, striatal cerebral microdialysis was performed from 1.5 h before until 8 h after tMCAO. Total infarct volume was largest in the normothermic group (89.9+/-16.8 mm(3)) followed by the fast rewarming group (69.2+/-12.6 mm(3)), and a significantly smaller infarct volume in the slow rewarming group (41.1+/-6.6 mm(3), p<0.05). Neurological functions improved in both hypothermia groups at day 5 after tMCAO (Neuroscore median 2.5 in normothermia vs. 1.5 in both hypothermia groups) though without any difference between slowly and fast rewarmed animals. Periinfarct expression of AQP4 was less prominent in slowly rewarmed animals as was the count of MPO-positive cells in subcortical regions. Glutamate release was significantly higher at 4 distinct time points in the control group. Slow rewarming after a period of hypothermia is superior to fast rewarming. It may blunt deleterious rebound effects such as overexpression of AQP4, sustain anti-inflammatory mechanisms and thereby preserve the neuroprotection delivered by hypothermia.     

Effects of hypothermia and rewarming on evoked potentials during transient focal cerebral ischemia in cats

We examined the effects of mild to moderate hypothermia and the influence of rewarming on electrophysiological function using somatosensory evoked potentials (SEPs) in transient focal ischemia in the brain. Nineteen cats underwent 60 min of left middle cerebral artery occlusion under normothermic (36 degrees-37 degrees C, n = 6) or hypothermic (30 degrees -31 degrees C, n = 13) conditions followed by 300 min of reperfusion with slow (120 min, n = 6) or rapid (30 min, n = 7) rewarming. Whole-body hypothermia was induced during ischemia and the first 180 min of reperfusion. SEPs and regional cerebral blood flow were measured before and during ischemia and during reperfusion. The specific gravity of gray and white matter was examined as the indicator of edema. During rewarming, SEP amplitudes recovered gradually. After rewarming, SEPs in the normothermic and rapid rewarming groups remained depressed (20%-40% of pre-occlusion values); however, recovery of SEPs was significantly enhanced in the slow rewarming group (p < 0.05). Hypothermia followed by slow rewarming reduced edema in gray and white matter. Rapid rewarming did not reduce edema in the white matter. The recovery of SEPs correlated with the extent of brain edema in transient focal ischemia. Rapid rewarming reduced the protective effect of hypothermia.     

亚低温联合β-七叶皂甙钠对实验性脑出血后AQP4表达及脑水肿的影响

目的 研究亚低温、β-七叶皂甙钠及二者联合对大鼠实验性脑出血后AQP4表达及脑水肿的影响.方法 270只健康成年SD大鼠随机分为假手术组30只,对照组、亚低温组、β-七叶皂甙钠组及联合组各60只,每组又分为5个亚组,分别于造模后1,2,3,5,7d断头取脑,其中半数大鼠进行脑含水量测定,另一半大鼠作免疫组织化学分析.在大鼠苍白球注射胶原酶制作脑出血模型,用冰块降温及白炽灯调整与动物距离照射加温的方法调节体温,采用干湿重法观察脑水肿的变化;应用免疫组织化学方法检测脑组织AQP4表达.结果 在各个时间点脑出血模型大鼠病灶侧脑含水量及AQP4的表达均明显高于假手术组(均P＜0.01),而亚低温组、七叶组及联合组均明显低于对照组(均P＜0.05);联合组在出血后5,7d病灶侧脑含水量及AQP4的表达均低于亚低温组及七叶组(均P＜0.05); AQP4表达水平与脑含水量呈正相关(r=0.970,P＜0.01).结论 亚低温及β-七叶皂甙钠均能明显减轻大鼠脑出血后脑水肿,而二者联合可能起到协同作用;亚低温及β-七叶皂甙钠可能通过抑制AQP4的表达而减轻脑水肿.     

大鼠重型颅脑损伤急性期水通道蛋白4的表达

目的探讨水通道蛋白（AQP4）在大鼠重型脑外伤急性期的表达变化及其与脑水肿间的关系。方法49只成年雄性SD大鼠,随机分为对照组及实验组（伤后4h、8h、12h、24h、5d共5组）。制作重度冲击加速性损伤模型,分别于伤后4h、8h、12h、24h、72h、5d采用干湿比重法测脑组织含水量,原子吸收分光光度法测定Na^＋、K^＋含量,Evans Blue（EB）测定法观察大鼠血-脑屏障（BBB）通透性变化,半定量逆转录聚合酶链反应（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4h开始表达上调,8h、12h依次增高,24h达到峰值（P〈0.05）,3d时仍维持较高水平,伤后5d有所降低。脑含水量、Na^＋含量的变化与AQP4 mRNA表达变化一致。经相关性分析,AQP4 mRNA的表达与脑含水量及脑EB含量均呈正相关（P〈0.05）。结论重型脑损伤急性期,AQP4 mRNA表达的变化与颅脑损伤后BBB的破坏及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。     

Glycerol accumulation in edema formation following diffuse traumatic brain injury

Traumatic brain injury (TBI) induces brain edema via water and glycerol transport channels, called aquaporins (AQPs). The passage of glycerol across brain cellular compartments has been shown during edema. Using a modified impact/head acceleration rodent model of diffuse TBI, we assessed the role of hypoxia inducible factor (HIF)-1alpha in regulating AQP9 expression and glycerol accumulation during the edema formation. Adult (400-425 g) male Sprague-Dawley rats received a closed head injury with a weight drop (450 g, 2-m height) and were allowed to survive up to 48 hours. Some rat groups were administered 2-methoxyestradiol (2ME2, a HIF-1alpha inhibitor) 30 minutes after injury and were euthanized at 4 and 24 hours after injury. Brain edema was measured directly by water content, and glycerol concentration was determined by the Cayman Glycerol Assay. HIF-1alpha and AQP9 protein levels were assessed by Western immunoblotting. This study demonstrated a significant (P<0·05) increase in brain water content at 4-48 hours following impact. Cerebral glycerol was significantly (P<0.05) up-regulated at as early as 1 hour and remained at high levels for up to 48 hours. Similarly, significant (P<0.05) increases in HIF-1alpha and AQP9 protein levels were found at 1 hour and up to 48 hours after injury. Compared to untreated but injured rats, inhibition of HIF-1alpha by 2ME2 significantly (P<0.05) reduced the TBI-induced AQP9 up-regulation. This reduction was temporally associated with significant (P<0.05) decreases in both edema and glycerol accumulation. The data suggested an associated induction of HIF-1alpha, AQP9, and extracellular glycerol accumulation in edema formation following diffuse TBI. The implication of HIF-1alpha and AQP9 underlying TBI-induced edema formation offers possibilities for novel TBI therapies.     

Therapeutic Hypothermia for Traumatic Brain Injury

Experimental evidence demonstrates that therapeutic temperature modulation with the use of mild induced hypothermia (MIH, defined as the maintenance of body temperature at 32-35?°C) exerts significant neuroprotection and attenuates secondary cerebral insults after traumatic brain injury (TBI). In adult TBI patients, MIH has been used during the acute "early" phase as prophylactic neuroprotectant and in the sub-acute "late" phase to control brain edema. When used to control brain edema, MIH is effective in reducing elevated intracranial pressure (ICP), and is a valid therapy of refractory intracranial hypertension in TBI patients. Based on the available evidence, we recommend: applying standardized algorithms for the management of induced cooling; paying attention to limit potential side effects (shivering, infections, electrolyte disorders, arrhythmias, reduced cardiac output); and using controlled, slow (0.1-0.2?°C/h) rewarming, to avoid rebound ICP. The optimal temperature target should be titrated to maintain ICP <20?mmHg and to avoid temperatures <35?°C. The duration of cooling should be individualized until the resolution of brain edema, and may be longer than 48?h. Patients with refractory elevated ICP following focal TBI (e.g. hemorrhagic contusions) may respond better to MIH than those with diffuse injury. Randomized controlled trials are underway to evaluate the impact of MIH on neurological outcome in adult TBI patients with elevated ICP. The use of MIH as prophylactic neuroprotectant in the early phase of adult TBI is not supported by clinical evidence and is not recommended.     

局部亚低温对脑缺血再灌注治疗时间的影响

目的观察有效再灌注时间窗内实施局部亚低温对不同时间点血管再通(再灌注)的影响,并探讨其机制。方法将150只雄性大鼠随机分为大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)24h组10只;常温再灌注组50只;MCAO 2h进行亚低温再灌注组50只;MCAO 3h进行亚低温再灌注组40只。动物均于再灌注24h后处死,但MCAO 24h组大脑中动脉闭塞24h后直接处死。采用TTC染色观察梗死体积,用干-湿质量法测定脑含水量,用原位末端标记(TUNEL)观察神经细胞凋亡的变化,采用免疫组化法检测大鼠模型的Bcl-2、Bax及水通道蛋白4(aquaporin4,AQP4)的表达。结果 MCAO 24h组的梗死体积、脑含水量、TUNEL阳性细胞数、及Bcl-2、Bax、AQP4的表达相比较,常温组2～3h有统计学差异(P<0.01),4～6h没有统计学差异(P>0.05);MCAO 2h亚低温再灌注组2～5h有统计学差异(P<0.01),6h没有统计学差异(P>0.05);MCAO 3h亚低温再灌注组3～4h有统计学差异(P<0.01),5～6h没有统计学差异(P>0.05)。亚低温再灌注组各时相点的梗死体积、脑含水量、TUNEL阳性细胞数、Bax、AQP4的表达均显著低于相应常温组,Bcl-2的表达显著高于常温组(P<0.01,P<0.05)。结论实施局部亚低温可延长再灌注治疗时间窗,而且亚低温开始时间越早,其延长时间窗的效果就越显著。这为解决在时间窗内就诊的患者因检查等错过再灌注治疗这一临床难题的解决提供了重要的实验室依据。其机制可能与抑制半暗带细胞的凋亡和改善微循环有关。