脑梗死大鼠神经前体细胞增殖水平的研究

目的研究脑梗死病灶周围及海马处神经前体细胞增殖水平的动态变化。方法采用易卒中型肾性高血压大鼠(RHRSP)，电凝大脑中动脉(MCA)主干制成脑梗死(MCAO)模型。行大鼠神经功能评定，免疫组化观察并计数梗死灶边缘、对侧镜区及双侧海马5-溴脱氧尿核苷(Bromodeoxyuridine，BrdU)标记的细胞。结果MCAO后大鼠神经功能评分减低，5d时恢复正常。MCAO后梗死灶边缘、对侧镜区及双侧海马均有BrdU阳性细胞分布，且病灶侧多于病灶对侧，集中分布于病灶周围。结论脑缺血可诱导神经前体细胞增殖并移向病灶，可能成为脑梗死恢复的重要物质基础。     

行为学训练对海马损伤梗死大鼠齿状回区BrdU和Nestin表达的影响

目的 探讨行为学训练对海马损伤梗死大鼠齿状回区神经干细胞增殖的影响。方法 采用光化学法制成单侧海马损伤梗死模型大鼠72只,随机分为训练组（n=36）和自由活动组（n=36）,每个组设1、7、14、21、28及35d 6个亚组。另设正常对照组36只,与模型组对应分为1、7、14、21、28及35d 6个亚组。训练组大鼠于造模1d后给予水迷宫训练,自由活动组大鼠自由活动,不予水迷宫训练。免疫荧光双标记法观察各不同时间点大鼠海马齿状回区溴脱氧尿嘧啶核苷（Bromodeoxyuridine,BrdU）与巢蛋白（Nestin）的双标记表达情况。结果 正常对照组大鼠海马齿状回区有少量BrdU/Nestin双标记阳性细胞,训练组及自由活动组大鼠在7、14、21及28d海马损伤梗死侧齿状回区BrdU/Nestin双标记阳性细胞数量均有显著增多（P <0.01）;训练组大鼠7、14、21、28d时海马损伤梗死侧齿状回区的BrdU/Nestin双标记阳性细胞数量显著高于自由活动组（P <0.01）;至35d时,训练组及自由活动组大鼠海马损伤梗死侧齿状回区BrdU/Nestin双标记阳性细胞数量与正常对照组无明显差异（P >0.05）。结论 行为学训练能显著增强海马损伤梗死大鼠齿状回区神经干细胞的增殖,促进神经功能恢复。     

成年大鼠脑创伤后神经前体细胞的增殖及迁移

目的 研究液压冲击性脑损伤后成年大鼠神经前体细胞的增殖及迁移。方法 制作液压冲击性脑损伤模型，免疫组织化学方法动态检测巢蛋白（Nestin）和5溴脱氧尿苷（BrdU）的表达。BrdU标记方法确定增列殖的前体细胞；Nestin的表达用于确定神经前体细胞。结果 同正常对照组相比较，伤侧皮层、海马及室下区的Nestin阳性细胞数于伤后1d明显增多，7d达高峰,30d消失；BrdU阳性细胞数于作后3d达高峰，而7d以后逐渐减小，室下区BrdU阳性细胞及Nestin阳性细胞经胼胝体向对侧迁移。结论 液压冲击性脑损伤可激发成年大鼠神经前体细胞增殖及迁移。     

脑梗死后康复训练对成年大鼠海马结构中神经干细胞的影响

目的　研究成年大鼠局灶性脑缺血损伤(脑梗死)后康复训练对海马结构中内源性神经干细胞增殖的影响,探讨脑梗死后康复训练使神经功能改善的理论基础。方法　采用线栓法造成成年大鼠永久性MCAO(middle cerebral artery occulsion),形成脑梗死动物模型。大鼠脑梗死24小时后,随机分为梗死对照组和梗死后康复训练组。康复训练组每天进行平衡木、转棒、滚笼训练,对照组不进行训练饲养于标准笼中。运用免疫组化方法,通过神经上皮干细胞蛋白即 nestin标记神经干细胞,观察、比较脑梗死后7天、14天、21天时两组大鼠海马结构中 nestin阳性细胞分布和数量的变化及差异。结果　脑梗死后两组大鼠梗死侧海马结构中nestin阳性细胞均较对侧显著增多,海马附近的侧脑室后角与CA1区之间及齿状回中阳性细胞密集,其中脑梗死后7天阳性细胞最多,以后逐渐减少。脑梗死后7天及14天康复训练组大鼠梗死侧海马结构中nestin阳性细胞数较对照组显著增加 (P < 0.01),脑梗死后21天两组无显著性差异(P >0.05)。结论　康复训练可以促进成年大鼠局灶性脑缺血损伤(脑梗死)后海马结构中神经干细胞增殖水平上调,这可能是脑梗死后康复训练有助于缺损的神经功能恢复的一个机制。     

大鼠脑缺血耐受与脑自体神经干细胞的增殖

背景：脑缺血耐受与脑自体神经干细胞均具有脑保护作用,但前者能否促使脑自体神经干细胞增殖,学者们报道不一致。 目的：明确缺血预处理与大鼠脑梗死后7 d海马区自体神经干细胞增殖的关系,以及其对大鼠脑梗死后神经行为学评分的影响。 方法：采用二次线栓法建立局灶-局灶性SD大鼠脑缺血耐受模型,40只SD雄性大鼠随机分为：假手术组,缺血组,假手术+缺血组,预缺血+缺血组,每组10只。脑梗死后3,7 d采用Zea-Longa评分方法进行神经行为学评分,运用荧光免疫组织化学技术检测大鼠脑缺血侧海马区BrdU标记阳性细胞数量。 结果与结论：脑梗死后3,7 d的Zea-Longa神经行为学评分,预缺血+缺血组低于缺血组、假手术+缺血组(P < 0.01),而缺血组和假手术+缺血组间差异无显著性意义(P > 0.05)。脑梗死后7 d缺血侧海马区BrdU标记阳性细胞数,缺血组、假手术+缺血组、预缺血+缺血组高于假手术组(P < 0.01);预缺血+缺血组高于缺血组、假手术+缺血组(P < 0.01);而缺血组和假手术+缺血组间差异无显著性意义(P > 0.05)。结果表明缺血预处理可促进大鼠脑梗死后海马区齿状回颗粒下层成体神经干细胞的增殖,并能改善其神经功能缺损症状。     

2003/成年大鼠脑出血后神经再生的实验研究

目的 观察大鼠实验性脑出血后内源性神经前体细胞的增殖、迁移、分布和在出血灶周边的分化。方法 将成年SD大鼠随机分为正常组、假手术组和脑出血组;脑出血组大鼠通过立体定向术向脑内注入自体动脉血制成脑尾壳核出血模型,并按不同的再喂养时间（1、3、7、14及30 d）分为5个亚组。手术后腹腔注射5-溴脱氧核苷尿嘧啶标记新生的内源性神经前体细胞。采用免疫组化单标观察内源性神经前体细胞（BrdU阳性细胞）的增殖、迁移和分布,免疫荧光双标观察内源性神经前体细胞在出血灶周边的分化情况。结果 与正常组和假手术组相比,脑出血组大鼠的BrdU阳性细胞数显著增加,并在7～14d达高峰;BrdU阳性细胞主要分布于室管膜下层、海马齿状回、脉络丛、胼胝体腹侧、出血灶周边区、外侧隔核、斜角带、缰核和大脑皮层等处。免疫荧光双标显示在脑出血灶周边区可见BrdU/GFAP、BrdU/NSE及BrdU/Nestin三种双标阳性细胞;BrdU/Nestin双标阳性细胞随着脑出血后时间的推移逐渐减少,而BrdU/GFAP、BrdU/NF-200双标阳性细胞则增多。结论 脑出血可诱导内源性神经前体细胞增殖,并向出血灶周边区迁移,进一步分化出神经元和胶质细胞,这可能是脑出血后神经结构重塑和功能恢复的重要物质基础。     

重复经颅磁刺激对脑梗死大鼠梗死侧皮质内源性神经干细胞激活、增殖的影响

目的研究重复经颅磁刺激(rTMS)对脑梗死大鼠神经功能恢复及梗死侧皮质内源性神经干细胞激活、增殖的影响。方法将72只雄性SD大鼠随机分为模型组、假刺激组、rTMS组,每组24只,各组根据脑梗死后不同时间点再分为1、7、14、21 d四个亚组,每个亚组6只。采用线栓法制作左侧大脑中动脉闭塞脑梗死模型。rTMS组于动物清醒后当天即给予每天2次、每次30个脉冲的rTMS治疗(频率为0.5 Hz,场强为1.33 T);假刺激组模拟rTMS固定大鼠头部放置线圈但不给予脉冲磁刺激;模型组不给任何治疗。各组在规定的时间点应用改良的神经功能缺损评分(mNSS)进行神经功能评定,治疗结束前24 h腹腔注射5-溴脱氧尿嘧啶核苷(BrdU),应用免疫组织化学技术检测梗死侧皮质巢蛋白(nestin)及BrdU表达阳性细胞的数量。结果 rTMS组脑梗死后7、14、21 d mNSS评分明显低于假刺激组及模型组同时间点大鼠(P<0.05),假刺激组及模型组大鼠脑梗死后不同时间点mNSS评分差异不明显(P>0.05)。脑梗死后1d模型组、假刺激组和rTMS组梗死灶周围皮质均可见nestin及BrdU阳性细胞,7 d达高峰。和假刺激组及模型组同时间点相比,rTMS组7、14、21 d nestin及BrdU阳性细胞数量明显增多,两者比较差异明显(P<0.05)。结论 rTMS能促进脑梗死大鼠神经功能恢复,机制可能与rTMS治疗能促进脑梗死周围内源性神经干细胞的激活及增殖有关。     

构建含2种营养因子和2套释放系统的三维仿生神经导管修复坐骨神经缺损

实验于大脑中动脉闭塞模型大鼠脑皮质梗死灶周围（梗死侧）和健侧脑皮质及两侧脑皮质移植嗅鞘细胞，观察到嗅鞘细胞向梗死灶迁徙。梗死区域生长相关蛋白43及神经纤维的数目均较移植前明显增多，但差异不明显，以上变化均以双侧细胞移植最为明显。说明嗅鞘细胞在脑梗死大鼠中具有较强的迁移能力，健侧脑移植嗅鞘细胞也能起到促进脑梗死大鼠的功能恢复，且双侧移植优于单侧移植。     

重复经颅磁刺激对局灶性脑缺血大鼠海马内源性神经干细胞增殖的影响

目的探讨重复经颅磁刺激（rTMS）对局灶性脑缺血大鼠海马内源性神经干细胞增殖的影响。方法线栓法制备大鼠大脑中动脉闭塞（MCAO）模型,50只造模成功的大鼠随机分为自然恢复组（n=25）和rTMS治疗组（n=25）,评定不同缺血时间点两组大鼠的神经行为,并用免疫荧光法检测不同缺血时间点两组大鼠海马BrdU-Nestin双标阳性细胞的数量。结果缺血后1d、3d、7d。两组大鼠的神经缺失行为无明显差异;缺血后14d、28d,rTMS治疗组大鼠的神经缺失行为较自然恢复组明显改善。两组大鼠海马BrdU-Nestin双标阳性细胞在缺血后1d开始增加,3d明显增加,7d达到高峰,14d下降;rTMS治疗组大鼠海马BrdU—Nest访双标阳性细胞数明显高于自然恢复组。结论rTMS可促进海马内源性神经干细胞增殖和脑缺血受损神经功能的恢复。     

脑心通对实验性脑梗死大鼠脑组织IL-6的影响

目的:探讨脑心通对实验性脑梗死大鼠脑组织中IL一6水平的影响。方法:参照Longa等方法制成大脑中动脉梗死(MCAO)模型,应用干一湿重法观察脑含水量变化、HE染色观察梗死周围炎性细胞浸润、免疫组化方法观察脑组织中lL一6的表达。研究不同剂量脑心通对脑梗死后大鼠行为学评分.脑含水量及脑组织中炎性细胞因子lL一6表达的影响。结果:脑梗死组织周围炎细胞浸润和IL一6阳性细胞表达于梗死后6h开始增多,48h达高峰,并持续到7d。脑心通治疗组大鼠脑梗死后脑水肿减轻,行为学评分降低,脑组织中IL一6阳性细胞减少,大、中剂量脑心通治疗组效果较为显著。结论:脑心通有抑制炎性细胞因子IL_6的过度表达,保护神经元,减轻脑水肿的作用。     

Electroacupuncture improves neurological deficits and enhances proliferation and differentiation of endogenous nerve stem cells in rats with focal cerebral ischemia

Abstract

Objectives: This study was carried out to observe the effect of electroacupuncture (EA) on neurological deficits, proliferation and differentiation of nerve stem cells (NSCs) in adult rats with middle cerebral artery occlusion (MCAO) and to study its possible role in the treatment of cerebral ischemic injury.

Methods: A rat model of MCAO was established and interfered with EA. On days 4, 7, 14 and 21 after ischemic injury, neurological deficits were scored. On days 4, 7, 14 and 21 after injury, effect of EA interference on the proliferation and differentiation of rat NSCs was observed with BrdU/NeuN and BrdU/GFAP immunofluorescence double labeling.

Results: A significant difference was found in the scores of rat neurological deficits between the EA and model groups 7, 14 and 21 days after cerebral ischemic injury (p<0·05). BrdU positive cells were found in the subventricular zone (SVZ) 4, 7, 14 and 21 days after ischemic injury. The number of positive BrdU cells in the SVZ reached its peak 7 days after injury and was greater in the EA group than in the model group 7 and 14 days after injury (p<0·05). The number of BrdU/GFAP doubly labeled positive cells in the SVZ was greater in the EA group than in the model group 7 and 14 days after ischemic injury (p = 0·012 and p = 0·025, respectively). There was no difference in the number of BrdU/NeuN doubly labeled positive cells 4, 7 and 14 days in the striatum, but a significant difference 21 days (p = 0·033) after ischemic injury between the two groups.

Discussion: Cerebral ischemic injury induces proliferation of NSCs, some of which will differentiate into both astroglia and neurons. EA may promote cells proliferation, stimulate the proliferating cells to differentiate into astroglia and mature into neurons, which may be one of the important reasons why EA can alleviate neurological deficits.     

Intrastriatal transplantation of bone marrow nonhematopoietic cells improves functional recovery after stroke in adult mice.

The authors transplanted adult bone marrow nonhematopoietic cells into the striatum after embolic middle cerebral artery occlusion (MCAO). Mice (n = 23; C57BL/6J) were divided into four groups: (1) mice (n = 5) were subjected to MCAO and transplanted with bone marrow nonhematopoietic cells (prelabeled by bromodeoxyuridine, BrdU) into the ischemic striatum, (2) MCAO alone (n = 8), (3) MCAO with injection of phosphate buffered saline (n = 5), and (4) bone marrow nonhematopoietic cells injected into the normal striatum (n = 5). Mice were killed at 28 days after stroke. BrdU reactive cells survived and migrated a distance of approximately 2.2 mm from the grafting areas toward the ischemic areas. BrdU reactive cells expressed the neuronal specific protein NeuN in 1% of BrdU stained cells and the astrocytic specific protein glial fibrillary acidic protein (GFAP) in 8% of the BrdU stained cells. Functional recovery from a rotarod test (P < 0.05) and modified neurologic severity score tests (including motor, sensory, and reflex; P < 0.05) were significantly improved in the mice receiving bone marrow nonhematopoietic cells compared with MCAO alone. The current findings suggest that the intrastriatal transplanted bone marrow nonhematopoietic cells survived in the ischemic brain and improved functional recovery of adult mice even though infarct volumes did not change significantly. Bone marrow nonhematopoietic cells may provide a new avenue to promote recovery of injured brain.     

脂肪来源干细胞移植对脑缺血大鼠运动功能的影响

目的 观察脂肪来源干细胞(ADAS)移植入脑缺血大鼠后存活、迁移、分化以及大鼠的运动功能障碍恢复情况,探讨ADAS移植治疗大鼠局灶性脑缺血的有效性和可能机制. 方法 将雄性SD大鼠饲养至250～300 g时,制作左侧大脑中动脉阻塞模型(MCAO),按照随机数字表法分为未处理组、对照组和移植组,每组6只.未处理组造模后不作特殊处理,对照组在造模后3h通过尾静脉注射杜氏改良培养基(DMEM),移植组造模后3 h通过尾静脉注射ADAS.造模后14 d处死大鼠,通过免疫荧光染色观察5-溴脱氧尿嘧啶核苷(BrdU)、神经元特异性烯醇化酶(NSE)、人微管相关蛋白2(MAP-2)和神经胶质纤维酸性蛋白(GFAP)的表达.造模后1、7及14 d时神经功能缺损评分评价大鼠运动功能改善情况. 结果 (1)移植后,标记了BrdU的ADAS大量出现在缺血灶周围;(2)MCAO后14d,缺血灶周围出现了少量BrdU/GFAP双染阳性细胞;同时出现少量BrdU/NSE和BrdU/MAP-2双染阳性细胞;(3)14d时移植组大鼠神经功能缺损评分与对照组相比明显降低,差异有统计学意义(P＜0.05). 结论 (1)成年大鼠ADAS在MCAO大鼠体内存活并少量分化为神经元样细胞和星形胶质细胞样细胞;(2)移植ADAS可使大鼠脑缺血所致的运动功能缺损得到改善.     

大鼠脑缺血再灌注诱导自体神经干细胞原位增殖的研究

目的研究缺血性脑损伤对内源性神经干细胞增殖、迁移的影响。方法参照Pulsinelli-Brierley法制作短暂性全脑缺血动物模型,全脑缺血10min后再灌注,采用SABC免疫组化染色显示5'-溴脱氧尿嘧啶(BrdU)阳性细胞和神经巢蛋白(Nestin)阳性细胞,光镜下观察并统计分析脑缺血损伤后内源性神经干细胞增殖、迁移的变化过程。结果脑缺血再灌流24h后,海马、齿状回和室管膜下区的BrdU阳性细胞和Nestin阳性细胞增多,7～10d达到高峰,术后20d仍有表达;在室管膜下区,BrdU阳性细胞和Nestin阳性细胞有向皮质、海马迁移的现象。结论①成年大鼠全脑缺血后7～10d,内源性神经干细胞的增殖达到高峰。②增殖的内源性神经干细胞存在由增殖区向靶区迁移的现象。     

大鼠局灶性脑缺血后少突胶质前体细胞激活及髓鞘再生的实验研究

目的探讨脑缺血再灌注大鼠少突胶质前体细胞(oligodendrocyte progenitor cells,OPCs)及髓鞘的表达变化。方法线栓法建立大脑中动脉闭塞(middle cerebral artery occlusion,MCAO)模型,免疫组化方法检测脑缺血再灌注后不同时间点1d、1w和2w不同脑区(梗死中心区、梗死周边区和梗死对侧区)OPCs特异性细胞标志物NG2的阳性细胞数及和髓鞘标志物碱性髓鞘蛋白(myelin basic protein,MBP)的表达变化。结果脑缺血后梗死中心区NG2阳性细胞数和MBP的表达随着再灌注时间延长而逐渐减少;梗死周边区NG2阳性细胞数在1w～2w增加,MBP的表达在24h～1w内降低,2w恢复到正常水平;梗死对侧区NG2阳性细胞数和MBP的表达无明显变化。梗死周边区OPCs细胞呈"单极"或"双极"分裂状,并从梗死灶的外带迁移到内带,提示OPCs细胞激活、增生并发生迁移。结论脑缺血再灌注后梗死周边区NG2细胞增多,使得一度缺失的成熟少突胶质细胞及髓鞘得到补充,提示NG2细胞可能参与缺血损伤的修复过程。     

Accumulation of corticosterone and interleukin-1β in the hippocampus after focal ischemic damage of the neocortex: Selective vulnerability of the ventral hippocampus

Most ischemic strokes are caused by the occlusion of the middle cerebral artery (MCAO), which results in focal brain lesions in different areas of the neocortex. Secondary damage develops in brain regions located out of the infarct area, including the hippocampus. Hippocampal lesion may lead to cognitive impairments and post-stroke depression. Here, we studied the time course of changes in the levels of corticosterone and proinflammatory cytokine interleukine-1β (IL-1β) in the blood and hippocampus of rats after transient focal brain ischemia. Activation of the hypothalamo–pituitary–adrenal axis, which causes a release of corticosterone into blood, was observed at the early stage after MCAO and was accompanied by the presence of the stress hormone in the hippocampi of both the ischemic and contralateral hemispheres. We show for the first time that this effect was observed only in the ventral hippocampus (VH) but not in the dorsal hippocampus (DH). MCAO induced accumulation of the proinflammatory cytokine IL-1β, which coexisted with the elevated level of corticosterone at the early and delayed stages after reperfusion and was also observed in the VH of both hemispheres. Our data show that the VH is more vulnerable to remote damage induced by MCAO compared to the DH and corticosteroid response and neuroinflammation may be detected in the VH of both ischemic and contralateral hemispheres.     

小鼠局灶性脑缺血模型中细胞间粘附分子-1表达升高

目的　白细胞可以导致缺血细胞损伤,内皮细胞上表达的细胞间粘附分子－１（ＩＣＡＭ－１）有利于白细胞迁移至组织。本研究目的是对小鼠大脑中动脉栓塞（ＭＣＡＯ）后脑内ＩＣＡＭ－１ 蛋白在组织中表达和含量进行检测。方法　通过对成年雄性ＣＤ－１ 小鼠使用血管腔内尼龙线栓塞术,造成０、３、６、１２、２４、４８ 和７２ ｈ 的持续性大脑中动脉栓塞。缺血程度由激光多普勒流量仪确定,缺血脑组织ＩＣＡＭ－１ 的阳性表达由免疫组化技术检测,并用免疫沉淀和Ｗｅｓｔｅｒｎ 印迹来定量。结果　在大脑中动脉栓塞后,小鼠缺血脑半球的表面脑血流量减少到基准值的９％ ～１５％ 。各组间大脑中动脉栓塞过程中的脑血流量无显著差异。免疫组化技术显示,缺血中心区和末影区都见ＩＣＡＭ－１ 阳性的微血管内皮细胞,从缺血中心到缺血边缘区微血管内皮细胞表达ＩＣＡＭ－１ 出现增高的趋势。免疫沉淀和Ｗｅｓｔｅｒｎ 印迹分析结果表明,缺血区ＩＣＡＭ－１的表达在大脑中动脉栓塞后３ ｈ 增高,６～１２ ｈ 达到高峰,并持续到７２ ｈ。结论　研究表明,在持续性大脑中动脉栓塞的小鼠中检测到ＩＣＡＭ－１ 表达明显升高,因为在持续局灶性大脑中动脉缺血后ＩＣＡＭ－１ 可介导白细胞和内皮细胞粘附,加速     

Endogenous neurogenesis and neovascularization in the neocortex of the rat after focal cerebral ischemia

The present study was designed to examine whether endogenous neurogenesis and neovascularization occur in the neocortex of the ischemic rat brain after unilateral middle cerebral artery occlusion (MCAO). Sprague-Dawley rats were divided into six groups (n = 29): one control group (n = 4) and five groups composed of animals sacrificed at increasing times post-MCAO (2 days and 1, 2, 4, and 8 weeks; n = 5 per group). To determine the presence of neurogenesis and neovascularization in the ischemic brain, nestin, Tuj1, NeuN, GFAP, Tie2, RECA, and 5-bromo-2'-deoxyuridine (BrdU) were analyzed immunohistochemically. In addition, nestin, GFAP, and Tie2 expression was determined by Western blotting. Triple-labeling of nestin, BrdU, and laminin was performed to visualize the interaction between endogenous neurogenesis and neovascularization. The number of BrdU- and nestin-colabeled cells increased markedly in the neocortex and border zone of the ischemic area up to 1 week after MCAO and decreased thereafter. Western blot analysis revealed that the expression of nestin, Tie-2, and GFAP was amplified in the ipsilateral hemisphere 2 days after MCAO and peaked 1 week after MCAO, compared with that in the normal brain. After ischemic injury, nestin- and BrdU-colabeled cells were observed in the vicinity of the endothelial cells lining cerebral vessels in the ipsilateral neocortex of the ischemic brain. Endogenous neurogenesis and neovascularization were substantially activated and occurred in close proximity to one other in the ipsilateral neocortex of the ischemic rat brain.     

Glucosylceramide synthase activity and ceramide levels are modulated during cerebral ischemia after ischemic preconditioning.

After 24-hour middle cerebral artery occlusion (MCAO) in spontaneously hypertensive rats, brain ceramide level increased from baseline reached 595% (ischemic core) and 460% (perifocal/penumbral areas); brain glucosylceramide synthase (GCS) activities in these areas simultaneously decreased by 70% and 50%, respectively. Ten-minute MCAO preconditioning significantly attenuated 24-hour MCAO-induced ceramide accumulation by 40% to 60% in ischemic core and perifocal areas, and GCS activities improved by 60% to 70% in both areas. Thus, potentially toxic levels of brain ceramide induced by MCAO were attenuated to intermediate levels in preconditioned animals; brain GCS activity was relatively preserved. In ischemic tolerance, GCS appears to modulate otherwise high levels of brain ceramide.