大鼠慢性脑灌注不足的病理与行为学观察

目的永久性结扎成年大鼠双侧颈总动脉导致慢性颈动脉系统灌注不足(CVI),分析其行为学及病理学改变。方法Wistar大鼠110只分为假手术组和单纯缺血组。单纯缺血组永久性结扎成年大鼠双侧颈总动脉建立大鼠CVI模型。于术后第3、9周行Morris水迷宫测试分析CVI大鼠术后视空间记忆损害的特点;采用HE、Bielschowsky银浸染法及免疫组织化学分析术后不同时间实验动物脑组织病理改变。结果各组大鼠均无明显运动功能障碍。单纯缺血组大鼠第3周平台定位时间、搜索策略均较假手术组明显延长(P<0.01),第9周尤为明显(P<0.001)。病理学结果显示,单纯缺血组呈轻度缺血性改变,神经元减少代之以胶质细胞增生;银染色法示部分顶叶、海马神经细胞嗜银样变,突起迂曲,类似神经元纤维缠结样改变。结论永久性结扎成年大鼠双侧颈总动脉引起的慢性CVI模型出现行为学障碍及脑组织轻度缺血性病理学改变,提示慢性CVI可能在神经变性疾病病理过程中起一定作用。     

氦氖激光对缺血缺氧性脑损伤新生大鼠认知功能的影响及机制研究

目的探讨氦氖激光对缺血缺氧性脑损伤(HIBD)新生大鼠脑认知功能的影响及可能机制。方法将Wistar新生大鼠随机分为假手术组、模型组和激光干预组。结扎新生大鼠左颈总动脉后,再吸入低浓度氧制备HIBD动物模型。Y-型迷宫检测大鼠学习记忆能力。免疫组织化学方法检测海马内Nestin和胆碱乙酰转移酶(choline acetyl transferase,ChAT)的表达。结果氦氖激光干预后HIBD大鼠学习记忆能力明显改善(P<0.05),与模型组相比,激光干预组海马区Nestin和ChAT的表达明显升高(P<0.05)。结论氦氖激光明显提高HIBD新生大鼠脑认知功能,机制可能与激光促进HIBD大鼠内源性神经干细胞增殖以及脑组织合成神经递质乙酰胆碱增多,进而提高缺血缺氧后神经细胞数量和功能有关。     

血管性痴呆大鼠认知功能及nNOS的表达

目的 探讨血管性痴呆(VD)大鼠认知功能、海马神经元结构及nNOS的表达.方法 采用双侧颈总动脉结扎法制备慢性前脑缺血动物模型,40只老龄大鼠随机分为假手术组(S)、模型组(M).应用水迷宫、透射电镜及免疫组化方法对2组大鼠学习记忆、神经元结构、nNOS表达进行观察.结果 与假手术组比较,大鼠水迷宫学习记忆能力在造模2个月后差异有统计学意义(P＜0.05),大鼠海马神经元在造模后变性水肿明显,大鼠海马及颞叶皮层nNOS在造模2个月后表达增加 (P＜0.05).结论 海马及颞叶皮层nNOS表达增加,神经元变性,可能导致血管性痴呆大鼠学习记忆障碍.     

脑缺血对大鼠皮层及海马铜蓝蛋白表达的影响

目的 探讨脑缺血对大鼠皮层及海马中铜蓝蛋白(Ceruloplasmin,Cp)表达的影响.方法 雄性Wistar大鼠60只,随机分为脑缺血1、3、7、28 d组和假手术对照组,每组各12只.实验组结扎双侧颈总动脉造成大鼠脑缺血,假手术对照组仅分离出双侧颈总动脉但不结扎.采用反转录聚合酶链反应(RT-PCR)检测皮层及海马组织中Cp mRNA的表达,免疫组织化学观察皮层及海马组织中Cp的表达.结果 大鼠皮层和海马均表达Cp mRNA.皮层和海马Cp mRNA的表达随缺血时间的延长逐渐降低,缺血1、3、7、28 d组表达均低于假手术组(P＜0.01).脑组织脉络丛细胞、室管膜细胞、皮层和海马的星形胶质细胞、血管内皮细胞均表达Cp;而皮层和海马的锥体细胞和颗粒细胞均不表达Cp.缺血1 d组皮层及海马Cp表达与对照组差异不显著(P＞0.05);缺血3 d组皮层和海马Cp表达低于假手术组(P＜0.05);缺血第7、28 d组Cp表达减少极为显著(P＜0.01).脑缺血大鼠皮层和海马中铁含量与Cp的表达呈负相关,相关系数分别为-0.831(P＜0.01)和-0.809(P＜0.01).结论 脑缺血可诱导大鼠皮层及海马中Cp表达降低.脑缺血后Cp表达减少可能参与了脑缺血引起的铁含量升高及神经元铁沉积的过程.     

依达拉奉对大鼠脑缺血后海马微血管密度NGF、BDNF表达的影响

目的探索依达拉奉对大鼠脑缺血后海马微血管密度、神经生长因子(NGF)、脑源性神经生长因子(BDNF)表达的影响。方法将Wistar大鼠分为假手术组、依达拉奉治疗组(以下简称治疗组)、缺血对照组。采用电凝右侧椎动脉和结扎双侧颈总动脉的方法制造大鼠脑缺血模型。分别给予治疗组和缺血对照组依达拉奉及等计量生理盐水腹腔注射。大鼠于相应时段灌注取材,每组标本分别采用单宁酸-氯化铁法染色微血管,免疫组织化学方法显示脑组织中的BDNF和NGF。光镜下观察脑组织中微血管密度、NGF和BDNF的变化,利用灰度值进行分析。结果微血管密度、NGF、BDNF灰度值治疗组均低于缺血对照组。结论 NGF、BDNF水平与微血管密度密切相关;依达拉奉可上调大鼠缺血脑组织中NGF、BDNF的表达,减轻脑组织损伤。     

肉苁蓉总苷对清醒小鼠脑缺血再灌注致海马CA1区脑组织损伤的保护作用

目的 探讨肉苁蓉总苷(GCs)对脑缺血再灌注所致清醒小鼠海马CA1区脑组织损伤的保护作用。方法 结扎小鼠右侧颈总动脉建立脑缺血及脑缺血再灌注模型，动态观察GCs对脑缺血3小时再灌注24及48小时两个时点脑梗死范围百分比、脑缺血3小时再灌注24小时海马CA1区脑组织病理变化及脑细胞凋亡情况的影响。结果 脑缺血及脑缺血再灌注后脑梗死范围百分比明显增加；海马CA1区脑细胞密度降低，细胞皱缩明显，胞浆染色较深，核染色质凝聚，凋亡神经细胞明显增多；与缺血组相比，缺血再灌注组损伤加重。GCs可促进上述各项指标的恢复，显著降低脑梗死范围百分比，减轻脑组织病理损伤，抑制脑细胞凋亡。结论 GCs对脑缺血再灌注小鼠脑组织具有保护作用，其机制可能与抗氧化及抗脑细胞凋亡作用有关。     

骨髓间充质干细胞移植对血管性痴呆大鼠海马胆碱能系统的影响

目的 观察同种异体骨髓间充质干细胞(BMSCs)对血管性痴呆(VaD)模型大鼠海马胆碱能系统的影响.方法 体外分离、扩增大鼠BMSCs,并用BrdU标记.采用双侧颈总动脉结扎法(2-VO)制备VaD模型.将大鼠随机分为3组:A组(BMSCs移植组):于双侧颈总动脉结扎后4周经尾静脉注射BMSCs;B组(对照组):注射同等剂量PBS;C组(假手术组):暴露双侧颈总动脉但不结扎,不进行尾静脉注射.BMSCs注射后4周,采用免疫荧光染色观察大鼠海马BrdU标记细胞;测定海马结构内乙酰胆碱酯酶(ACHE)及胆碱乙酰转移酶(ChAT)的活性.结果 BMSCs移植后4周A组大鼠海马结构可见荧光标记的BMSCs;A、B组AChE和ChAT活性均较C组降低(P＜0.05),且A组较B组显著增强(P＜0.05).结论 静脉移植BMSCs可增强VaD大鼠海马胆碱能系统活性.     

黄芪皂甙对大鼠脑缺血再灌流神经元一氧化氮合成酶的影响

选雄性Ｗｉｓｔａｒ鼠16只,分正常无缺血组(自身对照非缺血侧,8只);缺血再灌流组(缺血侧,8只);缺血再灌流黄芪皂甙治疗(ＡＳＳ)组(8只)。用插线法制作大鼠左侧ＭＣＡＯ模型。缺血2小时后,再灌流2小时,用ＮＡＤＰＨ-黄递酶(ｄｉａｐｈｅｒａｓｅ)(ＮＡＤＰＨｄ)组织化学染色法作ＮＯＳ染色。光镜观察细胞染色,高倍镜下对大脑皮质、尾壳核ＮＯＳ阳性神经元计数,并进行ｑ检验。结果显示:正常无缺血组可见ＮＯＳ阳性神经元呈蓝色,轴突清晰可见,神经纤维交叉成网状,大脑皮质ＮＯＳ阳性神经元数为(11.58±1.52)个/高倍镜,尾壳核为60.70±8.54。缺…     

神经元型一氧化氮合酶在血管性痴呆大鼠海马中的表达

目的 探讨神经元型一氧化氮合酶(nNOS)在血管性痴呆(VD)大鼠海马中的表达。方法 将60只大鼠随机分为：对照组、VD12h组、VD1d组、VD3d组、VD7d组。采用反复夹闭双侧颈总动脉方法建立VD大鼠模型，用HE染色观察各组大鼠海马CA1区神经元的数目；应用免疫组化染色和Western印迹方法检测nNOS在大鼠海马中的表达。结果 VD12h组、VD1d组、VD3d组、VD7d组大鼠海马CA1区神经元数均明显下降。nNOS在对照组大鼠海马CA1区中弱表达．在VD12h组表达增强．VD1d组进一步增强，VD3d和7d组表达逐渐减弱。结论 nNOS可能参与缺血早期海马神经元的损害，是VD的发病机制之一。     

PKA-CREB信号转导通路在大鼠慢性脑缺血所致认知功能障碍中的作用

目的:观察PKA-CREB信号转导通路在慢性脑缺血所致大鼠认知功能损害中的作用。方法:结扎大鼠双侧颈总动脉,制成慢性脑缺血模型,分缺血8周组和假手术对照组,术后第8周时用Morris水迷宫测定大鼠学习记忆能力。用Westernbloting检测大鼠海马胞核内PKAca及pCREB的表达。结果:缺血组与假手术组相比学习记忆能力明显下降(P<0.05),缺血组大鼠海马中PKAca及pCREB的表达与假手术组相比也下降(P<0.05),且两者之间的下降存在正相关关系。结论:PKA-CREB信号转导通路可能参与了慢性脑缺血所致大鼠认知功能的损害。     

脑缺血后脑内HSP70表达的实验研究

热休克蛋白(HSP)是细胞对缺血等应激反应的敏感标记.通过建立大鼠全脑缺血模型,采用HSP70单克隆抗体LSAB免疫组化技术对脑缺血再灌注后的神经元进行了检测.发现在海马CA_3区,齿状回,尾壳核及杏仁核等处的神经元中有HSP70过量表达,并于再灌注后48h达到高峰.初步研究了HSP70在不同神经元中的分布情况,基本肯定不同神经元中HSP70的表达与神经元对缺血的耐受性有关.     

血红素氧合酶-1及血红素氧合酶-2在大鼠局灶性脑缺血中的意义

目的　研究血红素氧合酶 1(HO 1)及血红素氧合酶 2 (HO 2 )在局灶性脑缺血中的作用。方法　采用大鼠大脑中动脉栓塞脑缺血模型 ,对 6 6只大鼠脑缺血后不同时间点进行HO 1、HO 2免疫组化染色及病理学研究 ,并用计算机图像分析技术计算两者表达水平。结果　栓塞后 30min大鼠皮质及海马即有HO 1阳性神经元及胶质细胞的表达 ,且随着时间推移HO 1的表达逐渐增强 ,到栓塞后 12h达峰值 (P <0 0 1) ,以后逐渐下降 ,栓塞后 1周仍有HO 1表达。HO 2在正常大鼠及梗死大鼠脑组织内均有表达。栓塞后不同时间段 ,HO 2阳性神经元的数量无明显变化 (P >0 0 5 ) ,但HO 2表达呈动态变化 ,2 4h时最高 (P <0 0 1) ,以后逐渐下降。结论　脑缺血时脑内HO 1、HO 2表达的不同变化 ,是脑组织对损伤恢复重要的机制之一。HO 1修复受损的神经元和胶质细胞 ,而HO 2在于维护正常细胞的稳定     

Inducible nitric oxide synthase appears and is co-expressed with the neuronal isoform in interneurons of the rat hippocampus after transient ischemia induced by middle cerebral artery occlusion

The hippocampus (dentate gyrus DG plus Cornu Ammonis, CA) is vulnerable to neuropathological events such as ischemia. The DG is a region where neurogenesis takes place and it has been demonstrated that ischemia stimulates neurogenesis. Nitric oxide (NO) plays a major role in ischemic damage evolution and increases in rat hippocampus after ischemia. No information is available on the presence of nNOS-immunoreactive(IR) neurons in the hippocampus of ischemic animals; whereas, the presence of the iNOS protein has been reported in the DG after focal ischemia.We evaluated, immunohistochemically, the cell types expressing nNOS and iNOS in the rat hippocampus by 24 up to 144 h after transient middle cerebral artery occlusion to ascertain whether ischemia induces changes in nNOS or iNOS expression and whether a relationship exists between these changes and the animal survival.nNOS-IR interneurons were detected in control and ischemic rats; in the latter, their number was significantly decreased at all time points. iNOS-IR interneurons appeared in the hippocampus of ischemic rats at 24 h; their number was significantly higher in the animals with longer survival and did not change at later time points. More than 50% of the nNOS-IR interneurons co-expressed iNOS-IR. All these changes were seen both in the ipsilateral and contralateral hippocampus.In conclusion, the focal ischemia affects the hippocampus which responds bilaterally to the injury. We hypothesize that the decrease in the nNOS-IR neurons is likely due to either a neuronal loss or a switching towards the iNOS production which, by inducing neurogenesis, might compensate the neuronal loss.     

The effect of MK-801 on cortical spreading depression in the penumbral zone following focal ischaemia in the rat.

Cortical spreading depression (CSD) is a transient depression of neuronal activity that spreads across the cortical surface. In the present studies, we have investigated CSD activity in the penumbral zone following permanent middle cerebral artery (MCA) occlusion in the rat (n = 16/group), using double-barreled Ca(2+)-sensitive microelectrodes. Measurements of CSD activity were made for 3 h in each animal. During this time, a varying number of spontaneous CSDs were seen in the control group (total was 30, with a range of 0-7/rat). These CSDs were of varying duration: "small" (approximately 1 min) and "big" (5-45 min) CSDs. During a CSD, the extracellular [Ca2+] decreased to 0.11 +/- 0.07 mM (mean +/- SD). After 3 h, the extracellular [Ca2+] in the cortex (penumbral zone) was either normal (10/16 rats) or lowered to 0.5 mM (2/16 rats) or to 0.1 mM (4/16 rats). In the caudate nucleus (ischaemic core area), all rats had an extracellular [Ca2+] of approximately 0.1 mM when measured after the 3 h recording period. Neuropathological evaluation of the brains of the animals, which had been allowed to survive for 24 h after MCA occlusion, revealed ischaemic damage in the dorsolateral cortex and caudate nucleus. Administration of the noncompetitive NMDA antagonist, MK-801 (3 mg/kg i.p.), 30 min after MCA occlusion resulted in 24 and 29% reductions in the volume of hemispheric and cortical damage, respectively, which was highly significant (p less than 0.0001); no protection was seen against caudate damage.(ABSTRACT TRUNCATED AT 250 WORDS)     

Different expression of glycogen synthase kinase-3beta between young and old rat brains after transient middle cerebral artery occlusion

Ischemia is a common stress to human brain and is difficult to cure in older individuals. To examine the differences of the response to cerebral ischemia between young and old rat brains, distributions of glycogen synthase kinase-3beta (GSK3beta) and tau proteins were analyzed after 90 min of transient middle cerebral artery occlusion (MCAO) in young (10-11 weeks) and old (15 months) rats by immunohistochemical analyses. At 4 h of reperfusion, strong cytoplasmic and nuclear immunoreactivity for GSK3beta was induced in neurons of lamina I, II, V and VI of the cerebral cortex and dorsal caudate in young brains, while the induction was not observed in lamina I and II of old cerebral cortex. The staining in lamina V and VI and dorsal caudate then gradually decreased until seven days of reperfusion in both animal groups. The staining of tau protein and terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) did not show any positive signals in the control brain, but showed positive signals after ischemia with a peak at 24 h and 3 days, respectively. No significant difference was observed in the temporal and spatial patterns of tau and TUNEL stainings between these two groups. These data suggest that GSK3beta may have a role in ischemic neuronal cell death, and that the different spatial expression of GSK3beta between young and old rat brains may partly explain the vulnerability of older neurons after ischemia.     

The effects of L-DOPA on glutamate dehydrogenase activity in the cerebral neurons of rats with different motor activities

We studied the brains of stress-resistant Wistar rats and stress-prone August rats under normal conditions and after long-term L-DOPA administration. We performed a histochemical study of glutamate dehydrogenase (GDH) activity in layers III and V of the sensorimotor cortex, caudate nucleus, nucleus accumbens, and the CA3 field of the hippocampus. We did not find any differences in the GDH activity in the brain structures of the control Wistar and August rats with high or low levels of locomotion in the “open field” test. The activity of GDH was higher in layer V of the sensorimotor cortex and the caudate nucleus and lower in the hippocampus of August rats with low levels of locomotion as compared to Wistar rats with high locomotor activity. Administration of L-DOPA resulted in an increase in GDH activity in the sensorimotor cortex, caudate nucleus, and nucleus accumbens in Wistar rats with high levels of locomotion in the “open field” test. In Wistar rats with low locomotor activity, L-DOPA activated GDH in the hippocampus and decreased its concentration in the caudate nucleus and nucleus accumbens. In August rats with low levels of locomotion, L-DOPA increased GDH activity in the caudate nucleus and nucleus accumbens and decreased it in layer V of the sensorimotor cortex. The local specificity of GDH activity in the rat brain under normal conditions and during dopaminergic system hyperfunction are discussed.     

丹参在缺血再灌注时的神经保护作用──成纤维细胞生长因子上调

丹参作为传统中药治疗缺血性脑血管病具有良好的疗效，本实验研究丹参是否通过影响成纤维细胞生长因子（ｂＦＧＦ）起修复作用。用大鼠线栓法缺血再灌注模型及免疫组化方法，发现大鼠缺血９０ｍｉｎ、再灌流４８ｈ后，缺血侧皮层、尾壳核及海马区ｂＦＧＦ样免疫反应增加及神经细胞变性；缺血后给予丹参（１５ｇ／　ｋｇ）大鼠，ｂＦＧＦ样免疫反应加强，并且缺血对应侧脑区也可见轻度的ｂＦＧＦ样免疫反应改变，且神经细胞变性程度较轻。提示丹参对脑缺血再灌流的保护作用可能与它加强ｂＦＧＦ的修复作用有关。     

脑缺血再灌注损伤后GAP-43蛋白的表达和意义

目的 探讨脑缺血再灌注损伤后生长相关蛋白-43（GAP-43）的表达对神经元轴突再生的可塑性变化.方法 成年健康雄性Wistar大鼠40只,随机分为正常对照组、假手术组和缺血1h再灌注2h、6h、12h、24h、48h、3d、7d、14d组,每组各4只（n=4）.应用线栓法制备大鼠脑中动脉闭塞再灌注模型（MCAO）,采用免疫组织化学方法检测GAP-43的表达并观察神经元轴突再生的变化,并进行计算机图像分析.结果 缺血再灌注2h,海马、皮质区及纹状体区GAP-43呈基础表达,6h、12h、24h、48h表达逐渐增高,7d达高峰,P＜0.05,14d达最低表达,P＜0.05.与假手术组比较有显著性差异,P＜0.05.正常对照组无表达.缺血再灌注48h～7d损伤区域神经元轴突呈出芽征,发出突触纤维.结论 脑缺血再灌注损伤后GAP-43呈非特异性表达,并促进神经元的修复和再生.     

Effects of deltamethrin on nitric oxide synthase and poly(ADP-ribose) polymerase in rat brain

The effects of deltamethrin on the activities of nitric oxide synthase (NOS) and poly(ADP-ribose) polymerase (PARP) and the protein expression of neuronal NOS (nNOS) and PARP in rat brain were investigated in the present study. The activity of NOS was significantly increased in cortex and hippocampus at 5 h after deltamethrin treatment, and maintained at an increased level at 24 h. The activity of PARP was also elevated at the same time points in the same brain regions of treated rats. By immunohistochemical analysis, it was demonstrated that the nNOS-immunoreactive cells were markedly increased at 24 h after treatment in the cortex and hippocampus, whereas few nNOS-immunoreactive cells were observed in the same brain regions of control and treated rats at 5 h after treatment. The immunoreactivity for PARP was also increased in the same brain regions, showing the similar time course of the induction of nNOS by deltamethrin. These results indicate that deltamethrin increases the activities of NOS and PARP and initiates the protein expression of nNOS and PARP, suggesting that NOS and PARP might play important roles in neurotoxicity of deltamethrin.