川芎嗪-丹参-当归配伍对大鼠脑缺血治疗时间窗的影响

目的研究川芎嗪-丹参-当归配伍对大鼠脑缺血治疗时间窗影响。方法应用线栓法制作大鼠MCAO模型。尾静脉给药对大鼠脑缺血模型进行干预。将60只成年雄性Wistar大鼠随机分成中药组和对照组。再将中药组和对照组随机分成5个小组,即MCAO2h,3h,4h,5h和6h组。中药组:川芎嗪(0.35mg/100g体重)+丹参(200mg/100g体重)+当归(165mg/100g体重)溶解于总体积1.5ml的等渗盐水中。对照组:等渗盐水1.5ml。给药时间:再灌注前20min、再灌注后12h和36h。再灌注48h后计算大鼠存活率、行神经功能缺损评分、脑血流量和脑梗死体积测定。结果大鼠存活率:中药组总存活率70%;各小组存活率分别为100.0%、83.3%、83.3%、66.7%和16.7%。对照组总存活率40%;各小组存活率分别为83.3%、50.0%、33.3%、16.7%和16.7%。神经功能评分:中药组2.12±0.38、2.52±0.45、2.69±0.51、3.39±0.51和4.63±0.71;对照组3.81±0.22、3.82±0.33、4.13±0.12、4.31±0.42和4.51±0.31。脑血流量变化相对值(%):中药组(155±31.42)、(139±39.53)、(129±31.69)、(113±29.98)和(83±41.63);对照组(93±519.12)、(87±29.22)、(81±29,.20)、(73±21.19)和(79±39.53)。大鼠脑梗死体积(mm3):中药组(128.2±65.2)、(183.1±78.2)、(221.5±41.3)、(347.1±37.7)和(403.12±61.8);对照组(183.2±71.3)、(249.6±37.2)、(347.5±14.4)、(381.3±12.0)和(415.61±32.7)。所有观测指标,各中药组与相应对照组(除MCAO6h组)比较,差异均有统计学意义(P<0.05或P<0.01)。结论川芎嗪-丹参-当归对大鼠脑缺血-再灌注损伤模型的治疗时间窗影响在2h～5h范围内。     

藻酸双酯钠对大鼠脑缺血再灌注后神经细胞保护作用的研究

目的探讨藻酸双酯钠(PSS)对脑缺血再灌注后神经细胞的保护作用。方法采用线栓法制作大脑中动脉阻断(MCAO)再灌注大鼠模型。PSS治疗组大鼠于再灌注即刻及再灌注24 h、48 h分别给予PSS(18.75 mg/kg)腹腔注射;对照组、假手术组和正常组均同时给予等量生理盐水腹腔注射。观察大鼠神经功能、脑梗死体积、组织学、超微结构和凋亡细胞数的改变。结果(1)PSS治疗组和对照组神经功能评分分别为(1.83±0.75)分和(2.83±0.75)分,脑梗死体积分别为(107.9±12.1)mm3和(150.3±30.5)mm3,两组比较差异有显著性(均P<0.05);(2)PSS治疗组大鼠脑组织缺血损伤改变明显轻于对照组,神经细胞的组织学和超微结构接近正常;(3)PSS治疗组细胞凋亡数于再灌注后1 h和3 h与对照组相比,差异均无显著性(均P>0.05),再灌注6 h、12 h、24 h、48 h及72 h凋亡细胞数明显少于对照组(P<0.05~0.01)。结论PSS能明显减轻大鼠脑缺血再灌注后的神经功能障碍和神经细胞损害,缩小脑梗死体积,抑制神经细胞凋亡,从而对神经细胞具有保护作用。     

动脉内亚低温对大鼠缺血再灌注损伤的脑保护研究

目的探讨血管内低温对于缺血再灌注损伤的脑保护作用。方法实验分A组:单纯缺血再灌注组;B组:20℃冷盐水灌注组;C组:10℃冷盐水灌注组。各组分别检测脑梗塞体积、各项生理指标、脑组织水含量、脑温和肛温;计算48h存活率和神经功能缺失评分。结果灌注20℃冷盐水可迅速将梗塞区皮质温度由(36.3±0.9)℃降至(34.4±0.8)℃,纹状体温度由(37.0±0.8)℃降至(35.1±0.8)℃,低温可持续1h以上;灌注10℃冷盐水可将梗塞区皮质温度由(36.1±0.2)℃降至(31.7±1.9)℃,纹状体温度由(36.6±0.4)℃降至(32.3±1.8)℃,低温可持续4h以上。与A组相比,B组和C组神经功能缺失评分有明显好转,脑梗塞体积显著减小,48h存活率明显增加(P<0.01)。结论局部低温灌注治疗可靠、有效,能明显缩小缺血后梗死体积,提高大鼠存活率,有较高的临床应用价值。     

活血化瘀汤对大鼠脑缺血-再灌注后免疫炎症反应的影响

目的 探讨活血化瘀汤对大鼠局灶脑缺血-再灌注免疫炎症反应的影响。方法 采用线栓法制备大鼠大脑中动脉阻塞(MCAO)模型。灌药组分别于术前胃灌注红花、桃仁、川芎、赤芍组成的活血化瘀汤,再灌注24 h后测定大鼠神经功能缺损程度;检测脑勺浆、血清C反应蛋白、补体、免疫球蛋白IgG及其病理电镜检查,并与对照组比较。结果 灌药组大鼠神经功能缺损程度较对照组轻(P<0.05);灌药组血清免疫球蛋白IgG,脑匀浆、血清C反应蛋白、补体比对照组低(P<0.05);病理损伤较对照组轻。高剂量灌药组中用药时间长组部分指标比用药时间短组低(P<0.05)。结论 活血化瘀汤可拮抗大鼠局灶脑缺血-再灌注后的炎症反应。     

神经生长因子对兔局灶性脑缺血再灌注损伤的治疗时间窗及MR影像学评价

目的研究神经生长因子(NGF)对脑缺血再灌注损伤保护作用的有效时间窗,同时利用MR成像技术对其进行评价。方法采用兔大脑中动脉阻断(MCAO)局灶性脑缺血2 h再灌注72 h模型,分别于缺血再灌注0、1、36、h应用微量进样器将NGF立体定向导入梗死灶周,并于再灌注不同时间点应用MR影像学、TTC染色和流式细胞术评价家兔梗死体积、神经功能缺损和凋亡状态。结果缺血再灌注0、13、h组梗死灶周注射NGF后,经MRI检查所测梗死体积分别为(229.9±17.1)(、260.7±24.2)、(314.6±25.3)mm3,与对照组[(468.6±29.7)mm3]比较差异有统计学意义(均P<0.01);缺血再灌注6 h组梗死体积为(441.1±14.8)mm3,与对照组比较差异无统计学意义(P>0.05)。采用TTC染色所测梗死体积与MRI检查结果一致。脑缺血再灌注3 h内注射NGF,其神经功能缺损评分明显降低,凋亡率明显下降;再灌注6 h后注射NGF则无明显作用。结论NGF对兔局灶性脑缺血再灌注损伤的有效时间窗为再灌注损伤3 h内,MR影像学检查可作为定量评价基因疗效的可靠指标。     

胃酶抑素A通过上调p-ERK1/2的表达来保护大鼠脑缺血再灌注损伤

目的 探讨胃酶抑素A(Pepstatin A)保护大鼠脑缺血再灌注损伤的潜在机制。方法 将48只成年雄性健康Sprague-Dawley大鼠随机分配至假手术组(16只)、生理盐水对照组(16只)及Pepstatin A干预组(16只); 大鼠大脑中动脉缺血再灌注模型遵照Zea longa线栓法制备,即缺血2 h即恢复血流灌注,再灌注24 h后处死大鼠; 干预组及对照组在脑缺血再灌注即刻分别经腹腔注射Pepstatin A配置液(0.2 mL/10 g)或等体积生理盐水; 脑缺血2 h再灌注24 h时采用标准评分法行神经功能缺损评分; 假手术组、对照组及干预组中随机各取8只检测脑梗死体积,余下8只大鼠行western blot检测p-ERK1/2及Caspase-3的表达水平。结果 神经功能缺损评分显示,假手术组大鼠行为学表现正常,评分为0分,干预组大鼠的评分均显著低于对照组(P<0.05)。TTC染色显示,假手术组脑组织无梗死灶,干预组大鼠的相对脑梗死体积显著低于对照组(P<0.05)。Western blot检测显示,对照组p-ERK1/2蛋白的表达水平显著高于假手术组(P<0.05); 干预组该蛋白的表达水平较对照组显著增加(P<0.05); 干预组Caspase-3蛋白的相对表达水平显著低于对照组(P<0.05)。结论 Pepstatin A可能通过上调p-ERK1/2的表达来减少脑梗死体积及细胞凋亡发生,从而保护大鼠脑缺血再灌注。     

达纳康抑制大鼠局灶性脑缺血再灌注损伤后P~(53)蛋白表达及细胞凋亡的研究

目的　研究达纳康在大鼠局灶性脑缺血再灌注损伤中的脑保护作用及其分子机制。方法　采用线栓法建立大鼠大脑中动脉 ( MCAO)缺血 1h再灌注 2 4 h模型 ,18只雄性大鼠随机分为假手术组、生理盐水对照组和达纳康治疗组 ,每组 6只。采用 Zea- L onga评分法观察神经功能缺损程度 ,采用免疫组织化学方法、TUNEL 法分别观察各组 P53蛋白表达和细胞凋亡。结果　假手术组神经功能缺失评分为 0分 ,高倍视野下无 P53蛋白染色阳性细胞及凋亡细胞 ;达纳康治疗组神经功能缺失评分 ( 0 .4 8± 0 .3 7分 )、P53蛋白染色阳性细胞数 ( 5 .16± 1.84个 /高倍视野 )、凋亡细胞数 ( 4 .18± 1.2 1个 /高倍视野 )均较生理盐水对照组 ( 2 .76± 0 .82分、10 .4 3± 1.5 6个 /高倍视野、8.16± 1.5 0个 /高倍视野 )显著减少 ( P<0 .0 1)。结论　达纳康可明显减轻局灶性脑缺血再灌注损伤 ,其抑制神经细胞P53蛋白的表达 ,进而抑制细胞凋亡 ,是其脑保护作用的分子机制之一。     

糖尿病大鼠缺血再灌注脑组织NF-κB和ICAM-1的表达及意义

目的观察糖尿病大鼠缺血再灌注脑组织核转录因子(NF-κBp65)和细胞间粘附因子(ICAM-1)表达及意义。方法将89只Wistar大鼠随机分为对照组、假手术组、正常血糖缺血再灌注组(nIR)和糖尿病缺血再灌注组(dIR),观察时间点为再灌注0、6、12、24h,每个时间点各5只,用小剂量链脲佐菌素(STZ)腹腔注射诱发形成糖尿病大鼠模型,采用线栓法复制大鼠大脑中动脉闭塞再灌注模型,应用免疫组化的方法测定NF-κBp65和ICAM-1的表达水平。结果dIR组和nIR组NF-κBp65和ICAM-1主要表达于缺血周边区,dIR组再灌注0、6、12、24h NF-κBp65阳性细胞百分率分别为(24.7±4.2)、(53.4±8.0)、(72.4±7.2)、(60.7±5.0)%,与nIR组同一时间点比较差异有显著性(P<0.05);dIR组再灌注0、6、12、24h ICAM-1阳性微血管数分别为(0.8±0.8)、(2.4±1.6)、(5.1±2.1)、(3.6±1.6)条/8个400倍视野,与nIR组同一时间点比较0h组之间差异无显著性(P>0.05),而6、12、24h差异有显著性(P<0.05);缺血周边区脑组织NF-κBp65与ICAM-1的表达有明显的时间依从性。结论糖尿病大鼠缺血再灌注脑组织NF-κBp65和ICAM-1表达增加和表达时间提前可能是糖尿病加重脑缺血再灌注损伤的机制之一。     

达纳康抑制大鼠局灶性脑缺血再灌注损伤后P^53蛋白表达及细胞凋亡的研究

目的研究达纳康在大鼠局灶性脑缺血再灌注损伤中的脑保护作用及其分子机制.方法采用线栓法建立大鼠大脑中动脉(MCAO)缺血1h再灌注24h模型,18只雄性大鼠随机分为假手术组、生理盐水对照组和达纳康治疗组,每组6只.采用Zea-Longa评分法观察神经功能缺损程度,采用免疫组织化学方法、TUNEL法分别观察各组P53蛋白表达和细胞凋亡.结果假手术组神经功能缺失评分为0分,高倍视野下无P53蛋白染色阳性细胞及凋亡细胞;达纳康治疗组神经功能缺失评分(0.48±0.37分)、P53蛋白染色阳性细胞数(5.16±1.84个/高倍视野)、凋亡细胞数(4.18±1.21个/高倍视野)均较生理盐水对照组(2.76±0.82分、10.43±1.56个/高倍视野、8.16±1.50个/高倍视野)显著减少(P<0.01).结论达纳康可明显减轻局灶性脑缺血再灌注损伤,其抑制神经细胞P53蛋白的表达,进而抑制细胞凋亡,是其脑保护作用的分子机制之一.     

糖尿病大鼠缺血-再灌注对脑组织核转录因子-kBp65和基质金属蛋白酶-9表达的影响

目的 观察糖尿病大鼠缺血-再灌注后脑组织核转录因子-kBp65和基质金属蛋白酶-9的表达及意义.方法 89只Wistar大鼠随机分为正常对照组、假手术组、缺血-再灌注组和糖尿病缺血-再灌注组,采用腹腔注射小剂量链脲佐菌素诱发形成糖尿病大鼠模型,线栓法复制大鼠大脑中动脉缺血-再灌注模型;应用免疫组织化学方法分别检测再灌注0h、6h、12h及24h脑组织标本中核转录因子-kBp65和基质金属蛋白酶-9的表达水平.结果 糖尿病缺血-再灌注组和缺血-再灌注组大鼠核转录因子-kBp65和基质金属蛋白酶-9主要表达于缺血周边区.糖尿病缺血-再灌注组大鼠再灌注0h、6h、12h及24h核转录因子-kBp65阳性细胞百分率分别为(24.68±4.19)%、(53.37±7.86)%、(72.38±7.24)%和(60.66±5.02)%,与缺血-再灌注组同一时限相比差异有统计学意义(P＜0.01);基质金属蛋白酶-9阳性血管数分别为(0.83±0.81)支、(2.44±1.61)支、(5.08±2.11)支和(3.63±1.60)支,与缺血-再灌注组同一时限比较,再灌注0h组间差异无统计学意义(P＞0.05),而再灌注6h和12h组间差异有统计学意义(P＜0.01),其中24h组基质金属蛋白酶-9阳性表达低于12h组(P＜0.05).缺血周边区脑组织核转录因子-kBp65与基质金属蛋白酶-9的表达具有明显的时间相关性.结论 糖尿病大鼠缺血-再灌注后,脑组织对核转录因子-kBp65和基质金属蛋白酶-9的表达水平升高且表达时间提前,这可能是糖尿病加重脑缺血-再灌注损伤的机制之一.     

Effect of ischemia induced by middle cerebral artery occlusion on superoxide dismutase activity in rat brain

Acute cerebral ischemia increases the generation of free radicals, causing cell damage, and theoretically may decrease the activity of the scavenging enzyme superoxide dismutase. To investigate the role of superoxide dismutase in cerebral ischemia, we used a model of middle cerebral artery occlusion in rats. In this model an infarct is produced in the pyriform and frontoparietal cortices, extending into the lateral basal ganglia. We measured superoxide dismutase activity by using the xanthine oxidase cytochrome c reduction assay in these areas of rat brains. Tissue samples were analyzed 20 minutes, 2, 6, or 24 hours, or 7 days after middle cerebral artery occlusion and 2 or 24 hours or 7 days after sham operation (n = 8-10 at each time). There was no significant change in superoxide dismutase activity relative to control values in any brain area at any time up to 24 hours after surgery. However, 7 days after middle cerebral artery occlusion a significant decline in superoxide dismutase activity, to 55%-68% (p less than 0.05) of that in unoperated controls, was observed in all brain areas. Our results do not support an important role for changes in the activity of endogenous superoxide dismutase during the acute phase of cerebral ischemia. However, the decrease in superoxide dismutase activity 7 days after ischemia could indicate ongoing additional damage to peri-infarct tissue.     

钙拮抗剂对大鼠脑缺血后血脑屏障通透性的影响

目的 研究钙离子拮抗剂对大鼠脑缺血再灌注后血脑屏障(BBB)通透性和脑梗死灶体积的影响. 方法 插线法制作大鼠脑缺血再灌注模型.缺血2 h后再灌注.将150只大鼠按随机数字表法分尼莫地平组和对照组,每组分再灌注6h、12h、24 h、48h、72 h五个时间段,再灌注后尼莫地平组和对照组立即分别腹腔注射尼莫地平和生理盐水2 mg/kg.每12小时注射一次,用甲酰胺荧光法及透射电镜观察不同时段BBB通透性破坏的情况,TTC染色后计算梗死灶体积百分比.结果 大鼠脑缺血再灌注后BBB通透性和梗死灶体积百分比随时间延长逐渐增加.且BBB通透性的增加呈现两个高峰,第一个高峰在再灌注后12 h,第二个高峰在再灌注后48 h.尼莫地平组BBB通透性及脑梗死灶体积百分比的增加均较对照组明显,差异有统计学意义(P<0.05). 结论 脑缺血再灌注增加BBB的通透性和脑梗死灶体积百分比.再灌注后给予尼莫地平可加重这些病理变化.     

Influence of oxidative stress on induced tolerance to ischemia in gerbil hippocampal neurons

We investigated whether reversible oxidative stress induced by the administration of the superoxide dismutase inhibitor, diethyldithiocarbamate, could induce tolerance to subsequent cerebral ischemia in gerbil hippocampal neurons. Mature male gerbils received intraperitoneal injections of diethyldithiocarbamate (1.0 g/kg), which led to reduced superoxide dismutase activity and increases in thiobarbituric acid-reactive substance in the brain. Cerebral ischemia was produced by occluding the bilateral common carotid arteries for 5 min, either 2 or 4 days after diethyldithiocarbamate injection. One week after ischemia, samples from each brain were stained with hematoxylin-eosin to evaluate ischemic neuronal damage in the hippocampal CA1 sector. Diethyldithiocarbamate treatment 4 days before ischemia had significant protective effects against cerebral ischemia, while diethyldithiocarbamate 2-day pretreatment and vehicle treatment failed to show neuroprotection. Biochemical examinations showed a clear induction of heat shock protein 72 and a significant increase in manganese-containing superoxide dismutase in the hippocampus in animals treated with diethyldithiocarbamate 4 days prior to ischemia. These results suggested that the oxidative stress caused by diethyldithiocarbamate could induced tolerance to ischemia in the gerbil brain, and that the increase in the biosynthesis of manganese-containing superoxide dismutase and heat shock protein 72 could provide a biochemical explanation of the tolerance induced under these conditions.     

甘草总黄酮对大鼠局灶性脑缺血再灌注损害的脑保护作用

目的　研究甘草总黄酮对大鼠局灶性脑缺血再灌注损害的脑保护作用。方法　我们拟采用线栓法建立的大鼠大脑中动脉 (MCA)缺血再灌注模型 ,并用 3种不同剂量的甘草总黄酮灌服后 ,测定缺血 2h再灌注 2 4h时血清和脑组织中丙二醛 (MDA)、超氧化物歧化酶 (SOD)、一氧化氮 (NO)、一氧化氮合酶 (NOS)活性。结果　发现甘草总黄酮能促进大鼠MCA、缺血再灌注 2 4h后神经功能恢复 ,甘草总黄酮能明显降低血清、脑组织中的MDA、NO含量 ,提高体内SOD的活性。结论　提示中药甘草总黄酮有抗氧化作用     

Polyethylene glycol superoxide dismutase and catalase attenuate increased blood-brain barrier permeability after ischemia in piglets.

BACKGROUND AND PURPOSE: Transport of urea across the blood-brain barrier is increased during postischemic cerebral reperfusion in the piglet. Ischemia/reperfusion also has been observed to increase apparent superoxide anion generation on the surface of the brain. The present study was designed to address the hypothesis that the increased transfer of urea into the brain after ischemia/reperfusion could be due to superoxide anion-induced alterations in blood-brain barrier permeability. METHODS: Blood-to-brain transfer of carbon-14-labeled urea was measured in four groups (n = 7 each) of newborn pigs: 1) control (no ischemia, no pretreatment), 2) pretreatment with polyethylene glycol superoxide dismutase (1,000 IU/kg) and polyethylene glycol catalase (10,000 IU/kg i.v.) but no ischemia, 3) no pretreatment and 20 minutes of ischemia followed by 2 hours of reperfusion, and 4) pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase in addition to ischemia/reperfusion. The following brain regions were investigated: cerebrum, caudate, midbrain, pons, medulla, and cerebellum. RESULTS: Polyethylene glycol superoxide dismutase inhibited generation of superoxide anion by the brain during reperfusion after ischemia. Regional transfer of [14C]urea from blood to brain increased at 2 hours' reperfusion. This ischemia-induced increase in blood-to-brain transfer of [14C]urea was attenuated by pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase: e.g., cerebrum Kin was 28 +/- 2 in the control group, 26 +/- 3 in the pretreated/no ischemia group, 67 +/- 5 in the untreated/ischemia group, and 40 +/- 2 ml.g-1.s-1.10(6) in the pretreated/ischemia group. After ischemia/reperfusion, cerebral blood flow was unchanged by pretreatment with polyethylene glycol superoxide dismutase and polyethylene glycol catalase. CONCLUSIONS: These data suggest that production of a partially reduced species of oxygen contributes to the increased urea transfer across the blood-brain barrier after ischemia in the newborn pig.     

Temporal profile of the superoxide dismutase and the ascorbic acid in focal cerebral ischemia]

It has been proposed that free radical reactions are involved in ischemic brain damage. Since irreversible pathological changes occurs very early phase of the focal ischemia and the ischemic brain edema reaches its peak at about 2 days of ischemia, the free radical reactions must take place before these changes. Superoxide dismutase is a famous enzyme that dismutase superoxide anion, which is believed to be one of the initiator of the free radical reactions. If superoxide anion plays a pivotal role in the genesis of pathological ischemic brain damage and edema, the activity of the enzyme may decrease in the early phase of ischemia. Ascorbic acid is also known to be a scavenger of superoxide anion, and brain tissue contains it in a high concentration. We investigated the changes in superoxide dismutase activity and concentration of reduced ascorbate in focal ischemia. Focal ischemia was produced in rats by permanent occlusion of the left middle cerebral artery. The animals were decapitated 30 minutes, 4, 24, and 48 hours after the operation. Middle cerebral artery territory of each cerebral hemisphere was homogenized and centrifuged with phosphate buffer. The supernatant was divided into two aliquots; one was dialyzed to remove ascorbate and the other was not. The SOD activity was measured by electron-spin-resonance (ESR) spin trapping method, and the ascorbic acid concentration was measured by high performance liquid chromatography with electrochemical detection (HPLC-ECD). Protein concentration was measured by Lowry's method. The enzyme activity was expressed as unit/mg protein, and the ascorbic acid concentration was expressed as microgram/g tissue. The SOD activity decreased markedly by dialysis.(ABSTRACT TRUNCATED AT 250 WORDS)     

Protective effect of oxysophoridine on cerebral ischemia/reperfusion injury in mice

Oxysophoridine, a new alkaloid extracted from Sophora alopecuroides L., has been shown to have a protective effect against ischemic brain damage. In this study, a focal cerebral ischemia/reperfusion injury model was established using middle cerebral artery occlusion in mice. Both 62.5, 125, and 250 mg/kg oxysophoridine, via intraperitoneal injection, and 6 mg/kg nimodipine, via intragastric administration, were administered daily for 7 days before modeling. After 24 hours of reperfusion, mice were tested for neurological deficit, cerebral infarct size was assessed and brain tissue was collected. Results showed that oxysophoridine at 125, 250 mg/kg and 6 mg/kg nimodipine could reduce neurological deficit scores, cerebral infarct size and brain water content in mice. These results provided evidence that oxysophoridine plays a protective role in cerebral ischemia/reperfusion injury. In addition, oxysophoridine at 62.5, 125, and 250 mg/kg and 6 mg/kg nimodipine increased adenosine-triphosphate content, and decreased malondialdehyde and nitric oxide content. These compounds enhanced the activities of glutathione-peroxidase, superoxide dismutase, catalase, and lactate dehydrogenase, and decreased the activity of nitric oxide synthase. Protein and mRNA expression levels of N-methyl-D-aspartate receptor subunit NR1 were markedly inhibited in the presence of 250 mg/kg oxysophoridine and 6 mg/kg nimodipine. Our experimental findings indicated that oxysophoridine has a neuroprotective effect against cerebral ischemia/reperfusion injury in mice, and that the effect may be due to its ability to inhibit oxidative stress and expression of the N-methyl-D-aspartate receptor subunit NR1.     

Polyethylene glycol-conjugated superoxide dismutase fails to augment brain superoxide dismutase activity in piglets

We studied the effect of intravenously administered polyethylene glycol-conjugated superoxide dismutase (8,000 units/kg) on brain superoxide dismutase activity in 44 1-2-week-old piglets in the absence and presence of global cerebral ischemia and reperfusion. Four groups (n = 6 each) of piglets not exposed to ischemia were studied. Enzyme administration increased plasma superoxide dismutase activity from less than 5 to 142 +/- 8 units/ml (mean +/- SEM) without increasing brain activity (e.g., activities in the caudate were 7.9 +/- 0.5 and 8.1 +/- 0.4 units/mg protein) for up to 2 hours following administration. Four additional groups (n = 5 each) of piglets were given either enzyme or polyethylene glycol 5 minutes prior to 10 minutes of global cerebral ischemia induced by aortic cross-clamping followed by either 5 or 45 minutes of reperfusion. Enzyme administration increased plasma superoxide dismutase activity from less than 5 to 144 +/- 5 units/ml but failed to increase brain activity even after 45 minutes of reperfusion (e.g., activities in the caudate were 8.5 +/- 0.3 and 8.6 +/- 0.6 units/mg protein). We conclude that intravenous polyethylene glycol-conjugated superoxide dismutase does not increase superoxide dismutase activity in the brain despite global ischemia and reperfusion.     

Nimodipine posttreatment does not increase blood flow in rats with focal cortical ischemia

We used laser-Doppler flowmetry to study the effect of nimodipine administered after the onset of focal cortical ischemia on regional cerebral blood flow in 16 halothane-anesthetized, mechanically ventilated Wistar rats. We selected the Wistar rats strain since it would provide a wide range of ischemia severities to test the vascular response to nimodipine. Laser-Doppler probes continuously recorded regional cerebral blood flow at two or three sites over the parietal cortex (dura intact) while brain temperature was regulated at 37 degrees C. Occlusion of the right middle cerebral and common carotid arteries reduced cerebral blood flow to a mean of 38% (range 13-77%) of baseline. Thirty minutes later, either 2 micrograms/kg/min nimodipine (n = 8) or its vehicle, polyethylene glycol 400 (n = 8), was administered by a continuous intravenous infusion. Over 60 minutes of treatment, both the nimodipine-treated and vehicle-treated groups showed a trivial (3%) mean increase in cerebral blood flow. Nimodipine failed to augment cerebral blood flow regardless of whether the cortex was severely, moderately, or mildly ischemic.