对微球囊栓塞大脑中动脉制作猕猴局灶性脑缺血再灌注模型的评价

目的 建立一种理想的猕猴局灶性脑缺血再灌注模型. 方法 成年健康猕猴12只(雌雄各半).经颈总动脉或股动脉介入手术,将标准微球囊导管插入大脑中动脉(MCA)的起始部,然后充盈微球囊阻断MCA血流,退出微球囊后实现MCA血流再灌注,建立大脑中动脉闭塞再灌注(MCAO/R)模型.通过脑血管造影、磁共振血管成像(MRA)、磁共振扫描成像(MRI)、氯化三苯基四氮唑(TIC)染色和神经行为功能评分对动物模型进行评价.结果 经颈总动脉或股动脉介入手术,可以在荧光屏直视下准确地将微球囊导管插入大MCA阻断其血流,MCA在MRA上不显像.MCA供血区磁共振T1、T2、DWI出现高信号区,TFC染色显示脑梗夕匕病灶,动物出现相应的神经功能障碍.该方法 成功率高、重复性好、操作简单. 结论 经股动脉微球囊导管介入手术建立猕猴MCAO/R模型是一种较为理想的方法 .     

大鼠大脑中动脉缺血后海马星形胶质细胞反应的研究

目的:观察大鼠大脑中动脉缺血后皮层损伤侧海马星形胶质细胞反应的变化。方法:采用大鼠大脑中动脉阻塞再灌流模型,应用免疫印迹和免疫组织化学方法测定脑缺血后3 d、7 d以及30 d皮层损伤侧海马胶质纤维酸性蛋白(GFAP)以及增殖细胞核抗原(PCNA)蛋白的表达,观察星形胶质细胞增殖的变化。结果: GFAP免疫组化结果显示,脑缺血后7d皮层损伤侧海马CA1、CA2区星形胶质细胞数量较假手术组增加且胞体增大;脑缺血后30 d皮层损伤侧海马CA1、CA2区呈胶质疤痕样改变。同时,免疫印迹法显示脑缺血后7 d皮层损伤侧海马GFAP表达增强;脑缺血后30 d皮层损伤侧海马GFAP表达增高更加明显。此外,免疫印迹法显示脑缺血后3 d皮层损伤侧海马PCNA蛋白表达水平升高;脑缺血后7 d PCNA蛋白表达水平达到峰值;脑缺血后30 d,PCNA蛋白表达水平降低,但仍高于假手术组。结论: 大鼠大脑中动脉缺血后可引起其皮层损伤侧海马星形胶质细胞过度反应和增殖。     

改良的短暂局灶性大鼠脑缺血模型

SD成年雄性大鼠34只，用多聚-L-赖氨酸处理的尼龙线从大鼠颈总动插入，送至大脑中动脉以阻断大脑中动脉（MCA）的血液，造成MCA供血区缺血，2小时后将尼龙线头端退出到颈内动脉的颈段，制成短暂局灶性脑缺血模型。再灌流0．5-48小时后，观察了缺血的神经症状、脑组织TTC染色以及HE染色所显示的缺血灶和缺血的组织学特征。所有实验组均出现程度相同的各种神经症状，正常对照组、假性手术对照组和缺血组对照侧TTC染色为红色，缺血区为白色．并且位于同侧视前区、纹状体及大脑皮质，随再灌流时间的延长缺血区逐渐扩大．到24小时组，缺血区扩散为整个MCA供血区。3小时内神经元主要为急性期改变，HE染色神经元肿胀或收缩，6小时出现不可逆的神经元改变，48小时内视前区和纹状体现出凝固性坏死。这一模型操作简单，重复性好、敏感性高、反应一致，且易再灌流，因此是比较理想的短暂性局灶性脑缺血模型，可为临床中风的药物研究提供基本条件。     

怎样产生氢核密度ρ和T1、T2加权图像

磁共振成像(magnetic resonance imaging, MRI)的主要成像参数是自旋核密度ρ、T1、T2,但ρ、T1、T2并不能在磁共振(magnetic resonance,MR)中直接测得,它们是隐含在弛豫过程(relaxation process)样品的磁化强度矢量M在感应线圈中感应出的电压信号中.成像参数ρ、T1、T2只能通过人为手段提高权重,以MR信号的形式表现出来,这种获得成像参数的方法与其它成像有很大不同.     

MCAO拟血管性痴呆大鼠模型的建立

目的:建立根据线栓法所致脑缺血再灌损伤模型制备方法改良的大脑中动脉梗塞(MCAO)拟血管性痴呆大鼠模型。方法:对ZeaLonga和Nagasawa法加以改进, 采用同侧颈总动脉永久结扎线栓法制备MCAO大鼠模型, 2h后实现大脑中动脉再灌。利用Morris水迷宫检测模型大鼠空间学习记忆能力, 利用组织学技术检测模型大鼠脑组织病理改变。结果:造模1个月后MCAO模型大鼠进行Morris水迷宫定位航行试验第4d的逃避潜伏期和第5d的逃避潜伏期分别显著长于正常组和假手术组, P值均小于0.05;第4d的游泳路径和第5d的游泳路径分别较正常组和假手术组显著延长, P值均小于0.05;病理组织观察结果显示, 模型大鼠大脑中动脉供血区存在明确显著的缺血坏死病灶, 而同时海马CA1区神经细胞结构排列紊乱、稀疏, 细胞数明显较少。结论:经改良后的大脑中动脉梗塞血管性痴呆大鼠模型是进行血管性痴呆病理机制及其药物疗效评价的理想动物模型。     

以桡动脉为移植体的颅内外动脉吻合术

对104侧桡动脉(第一段)、102侧甲状腺上动脉和101侧大脑中动脉皮质支的长度、直径进行了测量.以甲状腺上动脉为供血血管,桡动脉为移植血管与大脑中动脉(MCA)皮质支吻合.根据应用解剖学研究和临床应用,这种新术式有可行性。     

老年人内侧膝状体形态、血供和来源动脉的病理学改变

目的 :研究老年人内侧膝状体的形态、毗邻及供血动脉来源、分支、分布和病理改变。方法 :体视及手术显微镜下观察 60～ 80岁年龄的脑内侧膝状体的形态、毗邻和血供情况 ;取内侧膝状体来源动脉 (大脑后动脉 )光镜下观察动脉壁的病理改变情况。结果 :内侧膝状体呈半球形 ,动脉来源于大脑后动脉的分支 ,即丘脑膝状体动脉 ,脉络丛后内、外动脉和丘体动脉 ,每侧有小动脉 ( 6.8± 1 .5 )支 ,大脑后动脉粥样硬化改变者占 88.3 %。结论 :内侧膝状体动脉细小 ,仅由大脑后动脉供血 ,动脉硬化可致小动脉管腔狭窄 ,供血不足 ,可能是老年人听力下降的原因之一。     

缓激肽在大鼠局灶性脑缺血区的分布

目的　研究缓激肽 (BK)在大鼠局灶性脑缺血区的分布。方法　应用免疫细胞化学方法 ,结合光学显微镜观察缓激肽在大鼠局灶性脑缺血的分布。结果　脑缺血 3h后 ,大鼠损伤侧MCA分布区的神经细胞中 ,发现BK样免疫阳性反应物 ;而正常大鼠MCA供血区的神经细胞内未见有BK样免疫阳性反应物。结论　正常大鼠MCA分布区的神经细胞内不存在或存在非常少的BK ,但在缺血性损伤后 ,神经细胞内出现较多的Bk。     

脑底诸动脉及其分枝

使用材料是100具童尸(♂41,♀59),身长为50—120厘米。1.各脑动脉左右粗细的变化很大,左右等粗的约为半数,在左右不等粗的例数中,以左侧大于右侧的较多。2.大脑动脉环的类型:(1)闭锁型97±1.71%,开放型3±1.71%;(2)对称型23±4.20%,不对称型77±4.20。3.大脑前动脉与前交通动脉的类型:(1)有前交通动脉的88±3.24%,无前交通动脉的12±3.24%;(2)简单型44±4.96%,复杂型56±4.96%。4.大脑后动脉与后交通动脉的类型:(1)大脑后动脉内侧部大于同侧后交通动脉的有72.5±4.45%,(2)大脑后动脉内侧部小于同侧后交通动脉脉的有16.5±3.70%,(3)大脑后动脉内侧部与同侧后交通动脉等大的有11±3.12%。5.岛的出现率:基底动脉有9例,大脑前动脉有7例,小脑上动脉有1例。6.大脑前动脉发出分枝到对侧半球的旁中央小叶及楔前叶的有5例。7.前交通动脉发出胼胝体正中动脉的有8例。8.各脑动脉的核心枝:(1)大脑前动脉发出1条内侧前穿动脉及3—4条外侧前穿动脉;(2)颈内动脉发出2条纹状体内囊动脉;(3)大脑中动脉发出2—3条内侧穿动脉及4—5条外侧穿动脉;(4)脉络膜前动脉发出2—3条纹状体内囊动脉;(5)后交通动脉发出4—5条小枝到灰结节及乳头体等处;(6)大脑后动脉内侧部发出5—7条后穿动脉;(7)大脑后动脉外侧部发出2—3条外侧后穿动脉及3—4条膝状体丘脑动脉。     

血管介入法导入自体血栓建立猴局部脑缺血模型

目的：采用血管介入法导入自体血栓，建立猴局部脑缺血动物模型，为脑缺血的相关研究提供创伤小、应用前景大的基础研究平台。 方法： 以12只食蟹猴为实验对象，采用血管介入法从股动脉将微导管超选至大脑中动脉（MCA）M₁分枝，导入自体血栓堵塞MCA。 结果：栓塞后，数字影像血管造影系统下可见M1段以后的血管显影不良；1 h后，CT灌注成像均显示大脑局部血流量和血容量下降，血流平均通过时间延长；48 h后常规CT平扫可见典型的低密度陈旧性局部脑缺血病灶。栓塞后24 h内，取两只动物尸体解剖，大脑切片TTC染色，显示患侧MCA区脑梗病灶；其余动物清醒后，缺血对侧肢体均有不同程度的瘫痪，神经功能评分均＜60分。 结论： 用血管介入法导入自体血栓建立的猴局部脑缺血动物模型，插管和栓塞过程清晰、定位准确、创伤小、并发症少、结果与临床更相似，在脑缺血的相关研究中有着较好的应用前景。     

大鼠急性脑缺血再灌注模型的建立及CT灌注扫描的评价

目的在活体状态下应用CT灌注扫描技术,评价大鼠急性脑缺血再灌注模型的可靠性。方法利用线栓法建立大鼠急性脑缺血再灌注模型,并通过其CT灌注扫描图像与脑切片TTC染色图像相比较对模型进行评价。结果大脑中动脉栓塞后2 h,CT灌注扫描显示明确的缺血范围。持续栓塞组大鼠脑切片TTC染色均显示明显的脑梗死灶,与CT灌注扫描显示的缺血范围具有一致性;再通组大鼠回撤栓线后,栓塞侧脑血流能够恢复,TTC染色未发现明显梗死灶。结论线栓法制作可复性大鼠急性脑缺血模型稳定可靠,操作简单。如能用CT灌注扫描对梗死模型进行筛选则可进一步降低由模型变异引起的实验误差,从而为脑梗死的治疗研究提供可靠平台。     

Diffusion- and perfusion-weighted MR imaging of transient focal cerebral ischaemia in mice

Temporary focal ischaemia was induced in wild-type C57Black/6 mice by thread occlusion of the middle cerebral artery (MCA). Recirculation was started after 60 min and maintained for 24 h, after which the mouse brain was frozen in situ. Development of the cerebral infarct was monitored by diffusion-, perfusion- and T(2)-weighted magnetic resonance imaging (MRI) during ischaemia, during the early reperfusion period of 90 min, and at 24 h after reperfusion. Ischaemia caused a marked reduction of the perfusion signal intensity and of the apparent diffusion coefficient (ADC) of tissue water in the ipsilateral MCA territory. In sham-operated control animals ADC remained unchanged. Hemispheric lesion volume after 1 h MCA occlusion was 53 +/- 6% (n = 6), as defined by an ADC decrease of more than 20%. Recirculation reduced hemispheric lesion volume to only 27 +/- 13%, while there was a trend towards secondary lesion growth at 24 h. Post-ischaemic recovery of perfusion was slow, heterogeneous and incomplete. A region-of-interest analysis showed only partial and transient recovery of the ADC, particularly in the dorsolateral cortex and lateral caudate putamen, which may be explained by inadequate reperfusion in these regions. Detailed MRI studies of cerebral ischaemia and reperfusion may now also be performed in the transgenic mice.     

MR angiographic investigation of transient focal cerebral ischemia in rat

Contrast agent free time-of-flight magnetic resonance angiography (TOF-MRA) was applied to the intraluminal thread occlusion model of experimental stroke in rat. It was combined with perfusion- and diffusion-weighted imaging (PWI and DWI) sequences to correlate occlusion and reopening of the middle cerebral artery with alterations in these well-established magnetic resonance sequences. Since TOF-MRA can be repeated without limitations, the time course of vascular patency is demonstrated during an experimental period of up to 8 h (2 h control, 1 h ischemia, 3-6 h reperfusion). With an acquisition time of 10 min, TOF-MRA proved to be suitable to analyze the vascular state of occlusion and reperfusion repetitively in longitudinal studies. Spatial resolution was sufficient to observe neurovascular structural details. In eight out of 10 animals complete vessel occlusion by the intraluminal thread could be validated by an entirely extinguished signal of the ipsilateral middle cerebral artery (MCA) in the angiograms. This was in accordance with a perfusion deficit in the MCA vascular territory detected by PWI (reduction to 30.4 +/- 7.4% relative to contralateral side) and a disturbance of water ion homeostasis monitored by DWI in this area. One animal showed a delayed occlusion after 30 min of MCA occlusion, in another animal vessel occlusion failed. In seven out of the eight successful occlusion experiments there was immediate reperfusion after withdrawal of the thread. One animal showed a delayed reperfusion after suture retraction. Remarkable hemispheric differences in vascular branching of the MCA could be recognized in three out of 10 animals. In conclusion, TOF-MRA is considered a helpful method to survey even in small laboratory animals the correct time course of vascular occlusion and reopening in experimental ischemia, and provides complementary information to the tissue perfusion status monitored by PWI and the ischemic lesion territory detected by DWI.     

Structural MRI of carotid artery atherosclerotic lesion burden and characterization of hemispheric cerebral blood flow before and after carotid endarterectomy

Collateral circulation plays a major role in maintaining cerebral blood flow (CBF) in patients with internal carotid artery (ICA) stenosis. CBF can remain normal despite severe ICA stenosis, making the benefit of carotid endarterectomy (CEA) or stenting difficult to assess. Before and after surgery, we assessed CBF supplied through the ipsilateral (stenotic) or contralateral ICA individually with a novel hemisphere-selective arterial spin-labeling (ASL) perfusion MR technique. We further explored the relationship between CBF and ICA obstruction ratio (OR) acquired with a multislice black-blood imaging sequence. For patients with unilateral ICA stenosis (n = 19), conventional bilateral labeling did not reveal interhemispheric differences. With unilateral labeling, CBF in the middle cerebral artery (MCA) territory on the surgical side from the ipsilateral supply (53.7 +/- 3.3 ml/100 g/min) was lower than CBF in the contralateral MCA territory from the contralateral supply (58.5 +/- 2.7 ml/100 g/min), although not statistically significant (p = 0.09). The ipsilateral MCA territory received significant (p = 0.02) contralateral supply (7.0 +/- 2.7 ml/100 g/min), while ipsilateral supply to the contralateral side was not reciprocated. After surgery (n = 11), ipsilateral supply to the MCA territory increased from 57.3 +/- 5.7 to 67.3 +/- 5.4 ml/100 g/min (p = 0.03), and contralateral supply to the ipsilateral MCA territory decreased. The best predictor of increased CBF on the side of surgery was normalized presurgical ipsilateral supply (r(2) = 0.62, p = 0.004). OR was less predictive of change, although the change in normalized contralateral supply was negatively correlated with OR(excess) (=OR(ipsilateral) - OR(contralateral)) (r(2) = 0.58, p = 0.006). The results demonstrate the effect of carotid artery stenosis on blood supply to the cerebral hemispheres, as well as the relative role of collateral pathways before surgery and redistribution of blood flow through these pathways after surgery. Unilateral ASL may better predict hemodynamic surgical outcome (measured by improved perfusion) than ICA OR.     

MR imaging of postischemic neuronal death in the substantia nigra and thalamus following middle cerebral artery occlusion in rats

The goal of this study was to investigate apparent diffusion coefficient (ADC) and T(2) relaxation time (T(2)) in the substantia nigra and thalamus after middle cerebral artery occlusion in rats. In the substantia nigra ipsilateral to infarct, ADC was significantly lower and T(2) was significantly higher on the third and fourth days, but they did not change significantly on the first, second, eighth and 15th days. In the ipsilateral thalamus, ADC and T(2) did not change significantly between the first and fourth days, but were significantly lower on the eighth and 15th days. This combination of MR findings suggested that secondary degeneration in the thalamus was different from that in the substantia nigra.     

Induction of cyclooxygenase-2 mRNA and protein following transient focal ischemia in the rat brain

Expression of cyclooxygenase-2 (cox-2) mRNA and inducible heat-shock protein-70 (hsp-70) mRNA was studied with in situ hybridization techniques at 30 min and 4 h following 1 h transient middle cerebral artery (MCA) occlusion in the rat brain. In addition, immunoreactivity for cox-2 was studied after 8 h of reperfusion. Induction of hsp-70 and cox-2 mRNA was found in the brain side ipsilateral to MCA occlusion. Hsp-70 mRNA was induced in the parietal cortex and striatum within the territory of the occluded MCA. Induction of cox-2 mRNA was particularly seen in cortical layer II in the brain side ipsilateral to MCA occlusion. At 30 min of reperfusion, areas showing cox-2 mRNA induction included the cingulate and frontal cortices located perifocally to the areas showing hsp-70 mRNA induction, and the piriform cortex. At 4 h of reperfusion, induction of cox-2 mRNA was seen within the parietal cortex. At 8 h of reperfusion, immunoreactivity for cox-2 was mainly seen in the ipsilateral cortex. These results demonstrate that transient focal ischemia induces the expression of cox-2 mRNA and protein in discrete areas of the rat brain during reperfusion, which might lead to local increases of arachidonic acid metabolism     

Effect of tris-(hydroxymethyl)-aminomethane on experimental focal cerebral ischemia

Systemic and focal cerebral acidosis is considered deleterious to cell metabolism and neuronal recovery. We investigated the immediate effect of tris-(hyroxymethyl)-aminomethane (THAM), an alkalizing agent, on focal cerebral ischemia produced by occlusion of the left middle cerebral artery (MCA) in cats with systemic acidosis. Occlusion of MCA resulted in prompt decreases in local cerebral blood flow of the ipsilateral marginal and ectosylvian gyri from 47.7 ml/100 g per minute in control to 32.3 ml/100 g per minute and 8.3 ml/100 g per minute, respectively. In the control group, physiological saline was infused continuously and the treated group received 0.3 M THAM to normalize systemic and focal cerebral acidosis. There were no significant changes in the systemic arterial pressure, arterial PO₂ and PCO2 throughout the experiments in the two groups. Arterial pH decreased from 7.42 to 7.30 in the control, while it remained normal during THAM treatment. Extracellular pH of the marginal gyrus (peri-infarct zone) decreased from 7.39 to 6.87 with 6 h ischemia in the control group. In THAM infusion, extracellular pH was kept between 7.26 and 7.29, which was significantly higher than the control group. THAM significantly decreased infarct volume and lactate and water contents of the gray matter in the marginal gyrus at 6 h after occlusion. It is concluded that THAM infusion immediately after ischemia onset is considered effective in improving acidosis at the site of ischemic penumbra and consequently reduces lactate production, brain edema, and infarct volume.     

Expression of Fos-like immunoreactivity in the brain and spinal cord of rats following middle cerebral artery occlusion

 This study examined c-fos protein expression in the brain and spinal cord of rats following permanent occlusion of the middle cerebral artery (MCA) above the rhinal fissure. At 1 h after right-sided MCA occlusion, Fos-like immunoreactivity (Fos-LI) was detected in neurons not only in the ipsilateral cerebral cortex but also in the spinal cord. In the latter, Fos-LI was localized in the nucleus and perikarya of neurons in the grey matter, notably the large motor neurons in the ventral horn. Fos-LI was most intense at 2–4 h, but became undetectable after 48 h in the cerebral cortex and 72 h in the spinal cord. In sham-operated animals, Fos-LI was almost undetectable or virtually absent. It was also not detected in the core territory supplied by the MCA at any time points after arterial occlusion. When the ischaemia-induced neuronal damage in both the cerebral cortex and spinal cord was evaluated by Nissl staining, some neurons appeared atrophic. We conclude that the induction of Fos-LI in neurons of the cerebral cortex and spinal cord is linked respectively to early onset–short stimulation and persistent excitatory or disinhibition phenomenon as a result of focal ischaemic brain injury. Received: 16 September 1996 / Accepted: 29 November 1996     

Protective effect of estrogen in endothelin-induced middle cerebral artery occlusion in female rats

Estrogen is a powerful endogenous and exogenous neuroprotective agent in animal models of brain injury, including focal cerebral ischemia. Although this protection has been demonstrated in several different treatment and injury paradigms, it has not been demonstrated in focal cerebral ischemia induced by intraparenchymal endothelin-1 injection, a model with many advantages over other models of experimental focal ischemia. Reproductively mature female Sprague–Dawley rats were ovariectomized and divided into placebo and estradiol-treated groups. Two weeks later, halothane-anesthetized rats underwent middle cerebral artery (MCA) occlusion by interparenchymal stereotactic injection of the potent vasoconstrictor endothelin 1 (180 pmoles/2 μl) near the middle cerebral artery. Laser-Doppler flowmetry (LDF) revealed similar reductions in cerebral blood flow in both groups. Animals were behaviorally evaluated before, and 2 days after, stroke induction, and infarct size was evaluated. In agreement with other models, estrogen treatment significantly reduced infarct size evaluated by both TTC and Fluoro-Jade staining and behavioral deficits associated with stroke. Stroke size was significantly correlated with LDF in both groups, suggesting that cranial perfusion measures can enhance success in this model.     

脑缺血新模型:大鼠胡须体觉皮层局灶性缺血模型的建立

目的:建立一个简单、可靠的、可以直接研究单一功能变化和组织形态变化之间联系的大鼠胡须体觉皮层局灶性脑缺血模型。方法:大鼠经10%水合氯醛麻醉后,经右侧顶叶皮层处开颅,在显微镜下结扎大脑中动脉的2～3个分支。应用激光多普勒血流仪检测结扎前、后局部脑血流情况,细胞色素氧化酶染色确定胡须体觉皮层和梗死部位的关系,2,3,5-氧化三苯基四氮唑(TTC)染色检测梗死面积大小。胡须依赖实验检测胡须功能。结果:大脑中动脉主要侧支结扎后,梗死中心及周围局部脑血流明显下降。细胞色素氧化酶染色及TTC染色均示梗死区域位于胡须体觉皮层。局灶性缺血3d,测定梗死面积约占全脑面积的15%。梗死形成后大鼠胡须分辨物体纹理的能力下降。结论:选择性的将大鼠具有单一功能的胡须体觉皮层制作成局灶性脑缺血模型,提供了一个较好的研究功能变化和组织形态变化之间联系的脑缺血动物模型。