亚低温治疗对实验性大鼠脑出血的保护作用研究

目的　本文观察了３２ ℃亚低温对脑出血大鼠脑 Ｎａ＋ 、 Ｋ＋ 、水含量及超微结构的影响。方法　６６ 只大鼠随机分成三组： （１） 假手术对照组; （２） 常温脑出血组; （３） 亚低温脑出血组。结果常温出血组水、 Ｎａ＋ 含量随时间而增加, 而 Ｋ＋ 含量减少; 亚低温组水、 Ｎａ＋ 含量比常温组低, 而 Ｋ＋含量增加。超微结构显示亚低温组脑超微结构损害较常温组轻。结论　亚低温治疗对脑出血后脑水肿, 脑细胞结构有保护作用。     

脑温不同对大鼠缺血脑组织c-fos和bcl-2表达的影响

目的 :研究脑缺血后不同脑温对相关基因表达的影响 ,探讨亚低温脑保护作用的机制。方法 :Sprague -Dawley(SD)大鼠 ,随机分为常温 (37- 38℃ )脑缺血、亚低温 (31- 32℃ )脑缺血、高温 (41- 4 2℃ )脑缺血和假手术组 ,每组 12只动物。脑缺血动物模型采用改良的Pulsinelli四动脉阻断法。脑组织中Fos和bcl- 2蛋白的检测采用链菌素亲生物素 -过氧化酶连接法 (SP)免疫组织化学技术。结果 :常温脑缺血再灌注可诱导Fos蛋白的表达 ,亚低温可使Fos蛋白的表达提早而增多 ,高温却使脑缺血时Fos蛋白的表达减少。常温脑缺血再灌注可诱导大脑皮质bcl- 2蛋白表达 ;亚低温增加bcl- 2蛋白表达 ;高温减少bcl- 2蛋白表达。结论 :脑缺血后即时开始亚低温可增加Fos和bcl- 2蛋白的表达 ,是亚低温脑保护作用的机制 ;脑缺血后高温则加剧脑缺血损伤     

Diazepam-induced neuroprotection: dissociating the effects of hypothermia following global ischemia

Global cerebral ischemia produces hippocampal CA1 neuronal loss which in turn leads to deficits in memory related tasks. Previous studies have shown that the benzodiazepine diazepam is effective at attenuating this cell death and the related behavioural impairments. However these studies have been confounded by diazepam-induced hypothermia. In this study we sought to determine the neuroprotective efficacy of diazepam in the absence of hypothermia. Diazepam (10 mg/kg) was administered to two groups of gerbils at 30 and 90 min following a 5-min ischemic insult. In one group the brain temperature was monitored for 24 h post-ischemically but not regulated. In the second group, post-ischemic brain temperature was maintained at 36.5 degrees C to counteract the hypothermia produced by diazepam. Both behaviour (open field performance) and CA1 cell counts from these groups were compared to those from sham/normal, no drug ischemic and vehicle ischemic groups at 10 days survival. In animals treated with diazepam without temperature regulation, there was significant histological and behavioural protection at 10 days compared to untreated ischemic animals. Preventing hypothermia in diazepam-treated animals resulted in a decrease in the number of cells surviving (from 41.2 to 31.6% of sham) and abolished behavioural protection. Diazepam appears to have limited ability to attenuate neuronal loss and its neuroprotective efficacy is augmented by the concurrent hypothermic actions of the drug itself.     

高血压大鼠脑缺血再灌注损伤时的病理学变化

目的研究高血压大鼠在脑缺血损伤时的病理改变。方法用线拴法将肾性高血压大鼠制作成脑缺血再灌注模型,在光镜和透射电镜下观察脑组织的病理和超微结构改变。结果高血压组大鼠与正常大鼠相比,在局灶性缺血再灌注损伤时有明显的组织学改变。结论高血压可经过多种机制加剧脑缺血性损伤。     

高血压大鼠脑缺血再灌注损伤时的病理学变化

目的 研究高血压大鼠在脑缺血损伤时的病理改变.方法 用线拴法将肾性高血压大鼠制作成脑缺血再灌注模型,在光镜和透射电镜下观察脑组织的病理和超微结构改变.结果 高血压组大鼠与正常大鼠相比,在局灶性缺血再灌注损伤时有明显的组织学改变.结论 高血压可经过多种机制加剧脑缺血性损伤.     

Moderate hypothermia mitigates neuronal damage in the rat brain when initiated several hours following transient cerebral ischemia

Intraischemic moderate hypothermia generally protects the brain against ischemic cell death, while hypothermia instigated several hours into the reperfusion phase is considered to be less effective. Here we report the effect of hypothermia (32.5°–33.5°C) of 5-h duration, initiated at 2, 6, 12, 24 and 36 h into the recirculation phase following 10 min of transient cerebral ischemia, on ischemic neuronal injury in the hippocampus and striatum of the rat. Hypothermia induced at 2 h, and 6 h postischemia reduces neuronal damage in the entire hippocampal CA1 region by approximately 50%. In the lateral CA1 region hypothermia induced at 12 h postischemia, significantly mitigates necrosis. When initiated at 2 h postischemia, but not later, protection was also observed in the striatum. Hypothermia induced 24 and 36 h postischemia was ineffective. A period of hypothermia of 5 h, initiated 2 h postischemia, was required for marked neuronal protection in the CA1 region, while 3.5-h hypothermia decreased neuronal damage by approximately 10% and 30 min hypothermia was ineffective. The clinical implications of the data are that extended period of hypothermia initiated long into the recovery phase following ischemia may prove beneficial. Hypothermia protects brain regions displaying rapid as well as delayed neuronal damage, and a minimal time of hypothermia is required for effective neuronal protection. Also, strict temperature control for up to 24 h postischemia may be required for proper assessment of the efficacy of cerebro-protective drugs.Supported by the Swedish Medical Research Council (grant no. 08644), The Medical Faculty at Lund University, The Segerfalk Foundation, The Crafoord Foundation, Åke Wibergs Foundation, and the CNPq (Brazilian Council for Development of Science and Technology)     

东菱克栓酶对全脑缺血再灌流损伤脑保护作用的实验研究

本文采用Ｐｕｌｌｓｉｎｅｌｌｉ的４ＶＯ方法制作了大鼠全脑缺血再灌流动动物模型，采用ＴＢＡ法、ＤＴＮＢ直接法测定全脑缺血１０ｍｉｎ再灌流后４８ｈ海马区的过氧化脂质（ＬＰＯ）和谷光甘肽过氧化物酶（ＧＳＨ－Ｐｘ）含量变化，计量病理和电子显微镜观察病理变化及东菱精纯克栓酶对其含量变化和病理改变的影响。结果显示：（１）东菱克栓酶可降低海马区ＬＰＯ含量（Ｐ〈０．０１），使ＧＳＨ－Ｐｘ活性上升（Ｐ〈０．０１）。     

刺五加皂甙对脑缺血大鼠皮质少突胶质细胞变化的影响

目的观察刺五加皂甙对全脑缺血大鼠皮质少突胶质谱系细胞的影响作用,探讨其对缺血性脑损伤的防护作用机制。方法 70只SD大鼠随机分为假手术组、脑缺血组、刺五加皂甙组。采用四血管结扎的全脑缺血模型,制模成功后随机分为脑缺血组、刺五加皂甙组。刺五加皂甙组大鼠按剂量3.0mg/kg腹腔注射;用免疫组织化学法检测皮质少突胶质细胞标记物[2型星形胶质祖细胞标记物B5(A2B5)、少突胶质细胞标记物4(O4)、2’,3’-环核苷酸磷酸水解酶(CNPase)]及髓鞘碱性蛋白(MBP)表达的变化。结果与假手术组比较,脑缺血大鼠皮质A2B5表达1d时即已增多、1w时显著增多、并持续至1个月;O4、MBP表达于脑缺血1d时显著减少、1w时回升、1个月时恢复至假手术组水平;CNPase阳性表达在脑缺血后1d即显著下降、1w时减少到最低点、1个月时恢复至假手术组水平。与脑缺血组比较,刺五加皂甙组大鼠皮质A2B5表达有不同程度减少,O4、CNPase、MBP表达有不同程度增加。结论刺五加皂甙对少突胶质谱系细胞缺血性反应有保护作用。     

亚低温对大鼠短暂性全脑缺血后皮质NOS亚型表达及神经元凋亡的影响

目的观察亚低温对大鼠全脑缺血再灌注后皮质3种一氧化氮合酶亚型表达、一氧化氮产生以及神经元凋亡的影响,探讨亚低温的神经保护机制。方法成年雄性SD大鼠,采用双侧颈总动脉阻断闭塞+低血压法制备短暂性全脑缺血动物模型,随机分为常温缺血组、亚低温缺血组和常温假手术对照组;常温时的脑温为36.5℃～37.5℃,肛温为35.9℃～36.9℃;亚低温时控制在32.5℃～33.5℃,相对应肛温为32.2℃～33.1℃;分别于缺血后及亚低温治疗后30min、2h、24h和72h观察短暂缺血对脑组织一氧化氮合酶亚型表达及神经元凋亡的影响,以及亚低温对缺血性脑损伤的保护作用。行神经元尼氏体亚甲蓝染色观察神经元数目及形态学的变化;免疫组化染色检测神经元型、诱导型和内皮型一氧化氮合酶的表达水平;应用硝酸还原酶法检测硝酸盐/亚硝酸盐水平的变化;采用TUNEL染色法并结合电子显微镜观察神经元凋亡的变化。结果常温缺血组大鼠额叶皮质3种一氧化氮合酶亚型表达水平及硝酸盐/亚硝酸盐含量均明显高于常温假手术对照组(P<0.05或P<0.01),出现凋亡神经元;低温缺血组大鼠3种一氧化氮合酶亚型表达水平和硝酸盐/亚硝酸盐含量明显低于常温缺血组(P<0.05或P<0.01),未检测到凋亡神经元。结论脑缺血后一氧化氮参与了神经元的凋亡过程,而亚低温治疗可以     

低温对大鼠海马脑片缺氧无糖损伤的保护作用及其机制

目的利用离体海马脑片孵育液和电生理学技术研究低温对脑缺氧/无糖损伤的保护作用及其机制.方法 (1)观察大鼠海马脑片在缺氧/无糖条件下顺向群峰电位(orthodromic population spike,OPS)的变化及温度对它的影响;(2)用高效液相(high-performance liquid chromatography,HPLC)荧光法检测温度对缺氧/无糖导致的海马细胞外兴奋性/抑制性氨基酸(excitabilitory and inhibitory amino acid,EAA/IAA)水平变化的影响.结果 (1)37℃组海马脑片缺氧/无糖时缺氧损伤电位(hypoxic injury potential,HIP)出现率为87.5%(7/8),复氧/供糖1h后OPS恢复率为12.5%(1/8).低温组(32℃、25℃)OPS消失时间和HIP出现时间明显减少(P<0.01),复氧/供糖1h后OPS恢复程度(41%±34%、79%±33%)与37℃组(7.5%±21.2%)比较有显著性差异(P<0.05),而这3项指标25℃优于32℃;(2)37 ℃组缺氧/无糖时,EAA和IAA比对照组均显著增加(P<0.01),兴奋性毒性指数(excitory toxicity index,ETI)显著上升(P<0.01).复氧后各氨基酸水平均有所下降.而低温组缺氧/无糖导致的谷氨酸(Glu)、天门冬氨酸(Asp)和甘氨酸(Gly)升高显著减少(P<0.01),GABA却随着复氧时间的延长逐渐增加(P<0.01),ETI明显降低(P<0.01).这种效应25℃优于32℃.结论低温有明显的抗海马脑片缺氧/无糖损伤作用,其作用机制可能与低温维持了EAA和IAA的动态平衡,降低了EAA的兴奋性毒性作用有关.而其作用又以25℃优于32℃.     

Effects of combined postischemic hypothermia and delayed N-tert-butyl-a-pheylnitrone (PBN) administration on histopathological and behavioral deficits associated with transient global ischemia in rats

Previous cerebral ischemia studies have reported the limitations of restricted periods of postischemic hypothermia in producing long-term neuroprotection. The present experiment attempts to determine whether delayed treatment with the free radical scavenger N-tert-butyl-a-phenylnitrone (PBN) is protective at 2 months following transient global forebrain ischemia, and whether additive effects can be observed when PBN is administered in combination with moderate hypothermia. For this aim rats were subjected to 10 min of two-vessel forebrain ischemia followed by (a) 3 h of postischemic normothermia (37°C); (b) 3 h of postischemic hypothermia (30°C); (c) normothermic procedures combined with delayed injections of PBN (100 mg/kg) on days 3, 5 and 7 post-insult; (d) postischemic hypothermia combined with delayed PBN treatment; or (e) sham procedures. Outcome measures included cognitive behavioral testing and quantitative histopathological analysis at 2 months. Postischemic PBN injections induced a systemic hypothermia (1.5°C–2.0°C) that lasted for 2–2.5 h. Water maze testing revealed significant performance deficits relative to shams in the normothermic ischemic group, with the postischemic hypothermia and PBN groups showing intermediate values. A significant attenuation of cognitive deficits was observed in the animal group receiving the combination postischemic hypothermia and delayed PBN treatment. Quantitative CA1 hippocampal cell counts indicated that each of the ischemia groups exhibited significantly fewer viable CA1 neurons compared to sham controls. However, in rats receiving either delayed PBN treatment or 3 h of postischemic hypothermia, significant sparing of CA1 neurons relative to the normothermic ischemia group was observed. These data indicate that hypothermia combined with PBN treatment provides long-term cognitive improvement compared to nontreatment groups. PBN-induced mild hypothermia could contribute to the neuroprotective effects of this pharmacological strategy.     

升压联合亚低温治疗对局灶性脑缺血再灌注的脑保护作用

目的　观察升压联合亚低温治疗对大鼠局灶性脑缺血再灌注的脑保护作用。方法　 32只大鼠随机分为对照组、升压组、亚低温组、升压 亚低温组 ,采用大鼠局灶性脑缺血再灌注模型 ,观察各组神经功能缺损评分和脑梗死体积。结果　升压组、亚低温组及升压 亚低温组神经功能缺损评分 (P <0 .0 5 )、脑梗死体积 (P <0 .0 1)均明显低于对照组 ;升压 亚低温组脑梗死体积明显低于升压组和亚低温组 (P <0 .0 5 )。结论　升压、亚低温对局灶性脑缺血再灌注损伤有明显脑保护作用 ,升压联合亚低温应用效果更佳     

Morphological investigation of the neuroprotective effects of graded hypothermia after diverse periods of global cerebral ischemia in gerbils

Hypothermia is known to be the most effective method to protect the neuronal damage induced by ischemia. In the present study, we investigated the histopathological consequences of hippocampal CA1 pyramidal neurons as well as the glial reactions in the hippocampus, after diverse periods of ischemic insult at graded intra-ischemic hypothermia ranging from 32 to 20°C. Gerbils were exposed to forebrain ischemia by clamping the bilateral common carotid arteries for 5–120 min depending upon the temperatures. The morphological study was performed 7 days after ischemia or sham-operation. Histopathological evaluation of delayed neuronal death (DND) was performed by Cresyl violet (CV) staining and MAP2 immunoreactivity. Glial reactions were examined by GFAP immunostaining and isolectin B4 histochemistry, corresponding to astrocytes and microglia, respectively. The forebrain ischemia at 32°C for 10 min and at 28°C for 20 min did not induce DND in the CA1 region. However, the ischemia at 32°C for 20 min and at 28°C for 30 min caused extensive degeneration of CA1 pyramidal neurons as observed in normothermic ischemic animals. Under the condition of deep hypothermia, the ischemia for 60 min at 24°C and for 120 min at 20°C which were the longest durations of each temperature within the limitation of the animal survival following 7 days, induced no DND in CA1 pyramidal neurons. The reactive changes of astrocytes were observed not only in ischemic animals with DND, but also in ischemic animals without DND. Computer image analysis showed that the area fraction of GFAP-positive structures in the CA1 region was significantly increased in both ischemic cases with and without DND compared with each sham group. In contrast, the distribution of activated microglia was much more restricted to the CA1 region and they were always accompanied by DND at 7 days postischemia. The present results demonstrate the remarkable neuroprotective effect of deep hypothermia that has been widely used in cardiovascular surgeries as the cerebroprotective strategy during total circulatory cessation. The findings also suggest that even under the condition of hypothermia, glial reactions may play an important role in neuronal survival and death after ischemia.     

脑缺血后脑室内注射胰岛素减轻大鼠学习记忆力损害的实验研究

目的探讨经脑室直接注射胰岛素对全脑缺血后大鼠学习记忆力的影响.方法以4-VO法建立大鼠全脑缺血再灌注模型.全脑缺血20min后行再灌注,于再灌注即刻经脑室注入1U胰岛素,缺血再灌注后8周利用三等分Y型迷宫箱测试大鼠的学习记忆功能,并对大鼠海马CA1区神经元的病理改变进行观察.结果经Y型迷宫测试,对照组、治疗组及缺血组大鼠达9/10正确反应所需电击数分别为5.6±1.2,8.6±1.3,19.6±2.6;对照组、治疗组及缺血组大鼠海马CA1区神经元计数分别为176.5±10.6,112.4±11.7,10.5±0.4.结论全脑缺血后脑室内注射胰岛素可明显减少大鼠海马CA1区神经元的死亡,进而减轻大鼠学习记忆力损害.     

栀子苷预处理对脑缺血再灌注大鼠血脑屏障的保护作用

目的观察栀子苷预处理对脑缺血再灌注血脑屏障(blood brain barrier,BBB)损伤的保护作用。方法采用线栓法建立大鼠大脑中动脉缺血再灌注(middle cerebral artery occlusion/reperfusion,MCAO/R)损伤模型,设假手术组、模型组以及栀子苷预处理组。通过紫外分光光度计检测脑组织伊文思兰(Evans blue,EB)含量,观察大鼠BBB通透性改变。用免疫组化染色法观察缺血侧额叶皮质区胶质纤维酸性蛋白(glial fibrillary acidic protein,GFAP)、基质金属蛋白酶-9(matrix metallopeptidase-9,MMP-9)及基质金属蛋白酶-2(matrix metallopeptidase-2,MMP-2)的阳性表达。用Western blot法检测水通道蛋白-4(Aquaporin-4,AQP4)的表达。结果 (1)再灌24 h后,大鼠脑组织EB含量明显增加,栀子苷预处理组较之于模型组EB含量降低(P<0.05);(2)模型组GFAP、MMP-9及MMP-2阳性表达与假手术组相比显著增加(P<0.01),而栀子苷预处理明显降低GFAP和MMP-9及MMP-2的表达(P<0.01;P<0.05);(3)缺血再灌注损伤后AQP4的表达显著提高,栀子苷预处理下调AQP4的表达(P<0.05)。结论栀子苷预处理对大鼠脑缺血再灌注引起的BBB损伤具有保护作用。     

亚低温对颅脑创伤大鼠脑血流量及组织间液乳酸水平的影响

目的 利用微透析技术观察颅脑创伤大鼠伤后2.5h内邻近受伤区侧脑室透析液中乳酸、脑血流量的变化及亚低温治疗效果。方法 28只Wistar雌性大鼠随机分为正常对照组、常温创伤组和亚低温治疗组。亚低温组动物于创伤后用冰袋进行全身降温,在脑温降至30℃并保持1h后,加热复温至37℃。将透析管插入邻近受伤区的侧脑室区,位于前囱后1.5mm,中线旁2.5mm,深度3.5mm;灌流速度为4μl/min,每30min采1管样本,后两组均于收集第2管样本后制作颅脑创伤动物模型,继续透析至2.5h。应用激光多普勒血流仪监测脑血流量的变化。结果 (1)对照组大鼠透析液中乳酸水平在各时限内差异无显著性意义(P>0.05);常温创伤组于伤后1.5h内乳酸水平明显升高,与对照组比较差异有显著性意义(P<0.01);亚低温组经低温治疗后,乳酸水平降低,与其余两组相比差异有显著性意义(均P<0.01)。(2)常温创伤组大鼠,仅在伤后20min时出现脑血流量减少,与对照组比较差异有显著性意义(P<0.05);而其余各时限与对照组比较差异均无显著性意义(P>0.05)。亚低温组经治疗后2h内脑血流量持续降低,与常温创伤组比较差异有显著性意义(P<0.05)。结论 亚低温治疗可降低损伤区周围脑组织血流量,加速大鼠神经细胞对乳酸的代谢,从而起到神经细胞保护作用。     

Long-term effects of clomethiazole in a model of global ischemia

The failure of neuroprotective drugs in clinical trials has raised questions about the predictive value of animal models. To address this issue we reexamined the efficacy of clomethiazole using functional and histological outcome measures in combination with long-term survival times. Gerbils were exposed to 5 min of global ischemia and received 400 mg/ml clomethiazole (via osmotic minipump) plus a bolus injection (60 mg/kg) 30 min after ischemia. Brain temperature was maintained at approximately 36.5 degrees C during ischemia and for the first 30 min after ischemia, and was monitored in all groups for 24 h. Subgroups of clomethiazole-treated gerbils had their temperatures regulated in the normothermic range while in other animals temperature was not controlled. Open-field habituation tests were conducted 5, 10, 30, and 60 days after occlusion. CA1 cell counts and CA1 slice recordings were done at the conclusion of behavioral testing. Clomethiazole significantly attenuated CA1 cell loss at 10-, 30-, and 60-day survival. A modest reduction in habituation deficits was evident only on Day 10 (P < 0.05). Similarly, field potential amplitude was not maintained in the rostral CA1 region. Clomethiazole produced mild hypothermia that developed over several hours. Based on short-term CA1 cell counts, clomethiazole provided significant histological protection with limited functional preservation. Neuroprotection disappeared when longer survival times (60 day) were employed and temperature confounds eliminated. These data demonstrate the necessity of utilizing more clinically relevant survival times and carefully monitoring/regulating postischemic temperature when assessing potential neuroprotective compounds.     

低频脉冲磁场对全脑缺血再灌注大鼠脑电图及海马神经细胞的作用

目的探讨经颅低频脉冲磁场对全脑缺血再灌注大鼠海马神经细胞的作用。方法将24只SD大鼠随机分成对照组和磁辐射组，每组各12只，应用改良的Pulsineli4-VO法制做大鼠全脑缺血再灌注模型，磁辐射组在脑缺血模型完成后立即将其头颈部置磁场（20mT、10Hz）中轴中央，身体顺磁场方向放置，辐射45min，每天1次，作用4次后将大鼠记录脑电图后断头取脑，对照组同时处死断头取脑，应用Nissl染色及免疫组织化学方法进行海马神经细胞计数及凋亡相关基因caspase-3蛋白表达检测。结果磁疗组较对照组神经元数量多（P〈0．05），脑电图频率和波幅增高（P〈0．05），caspase-3蛋白表达低（P〈0．05）。结论低频脉冲磁场（20mT、10Hz）可以抑制大鼠脑缺血再灌注海马神经元的凋亡，对脑缺血再灌注损伤有保护作用。     

Neuroprotection of mild hypothermia: differential effects

To estimate whether mild hypothermia during repetitive hypoxia provides a neuroprotective effect on brain tissue, hippocampal slice preparations were subjected to repetitive hypoxic episodes under different temperature conditions. Slices of guinea pig hippocampus (n=40) were placed at the interface of artificial cerebrospinal fluid (aCSF) and gas (normoxia: 95% O₂, 5% CO₂; hypoxia: 95% N₂, 5% CO₂). Evoked potentials (EP) and direct current (DC) potentials were recorded from hippocampal CA1 region. Slices were subjected to two repetitive hypoxic episodes under the following temperature conditions: (A) 34°C/34°C, (B) 30°C/30°C and (C) 34°C/30°C. Hypoxic phases lasted until an anoxic terminal negativity (ATN) occurred. The recovery after first hypoxia lasted 30 min. Tissue function was assessed regarding the latency of ATN and the recovery of evoked potentials. The ATN latencies with protocol A (n=25) for the first and second hypoxia were 5.9±1.3 min (mean±S.E.M., 1st hypoxia) and 2.4±0.9 min (2nd hypoxia), with protocol B the latencies (n=7) were significantly longer: 25.2±7.1 min and 15.6±7.7 min. With protocol C (n=8), the latencies were 5.6±1.8 and 3.3±0.5 min. No differences were seen in the recovery of the EPs with protocols A–C. Our results suggest that a mild hypothermia is only neuroprotective if applied from an initial hypoxia onwards.     

抑肽酶对家兔脑缺血再灌注损伤的保护作用

目的观察抑肽酶对家兔全脑缺血再灌注损伤的保护效果.方法健康家兔16只,体重20～25kg,随机分为抑肽酶处理组(A组)和缺血组(C组),每组8只.利用"六血管"式模型阻断动脉30 min,恢复血流再灌注4 h.A组于缺血前10 min静注抑肽酶30000 U·