Increased expression of receptor for advanced glycation end-products worsens focal brain ischemia in diabetic rats

A rat model of diabetes mellitus was induced by a high fat diet, followed by focal brain ischemia induced using the thread method after 0.5 month. Immunohistochemistry showed that expression of receptor for advanced glycation end-products was higher in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Western blot assay revealed increased phosphorylated c-Jun N-terminal kinase expression, and unchanged phosphorylated extracellular signal-regulated protein kinase protein expression in the ischemic cortex of diabetic rats compared with non-diabetic rats with brain ischemia. Additionally, phosphorylated p38 mitogen-activated protein kinase protein was not detected in any rats in the two groups. Severity of limb hemiplegia was worse in diabetic rats with brain ischemia compared with ischemia alone rats. The results suggest that increased expression of receptor for advanced glycation end-products can further activate the c-Jun N-terminal kinase pathway in mitogen-activated protein kinase, thereby worsening brain injury associated with focal brain ischemia in diabetic rats.

Protection of 3'-methoxy-puerarin against focal brain ischemia and its association with c-fos expression

The present study established a rat model of focal brain ischemia by occlusion of the middle cerebral artery covered with FeCl3, and investigated the protective effect of 3＇-methoxy-puerarin. Hippocampal and cortical c-fos gene expression was determined using in situ hybridization. Results showed that 3＇-methoxy-puerarin reduced neurological deficit scores, cerebral infarcted zone and water content of brain tissues, dramatically increased the activity of catalase and glutathione peroxidase in the ischemia zone of the hippocampus, increased the activity of catalase in the cortex, decreased lipid peroxide and lactic acid contents in the hippocampus and cerebral cortex, and down-regulated c-fos gene expression in brain ischemic rats. Results demonstrated that 3＇-methoxy-puerarin exhibited cerebroprotective effects against focal brain ischemia, which involved c-fos gene expression.

Neuroprotective effects of meloxicam on transient brain ischemia in rats:the two faces of anti-inflammatory treatments

The inflammato ry response plays an important role in neuroprotection and regeneration after ischemic insult.The use of non-ste roidal anti-inflammatory drugs has been a matter of debate as to whether they have beneficial or detrimental effects.In this context,the effects of the anti-inflammatory agent meloxicam have been scarcely documented after stro ke,but its ability to inhibit both cyclooxygenase isoforms(1 and 2) could be a promising strategy to modulate postischemic inflammation.This study analyzed the effect of meloxicam in a transient focal cerebral ischemia model in rats,measuring its neuroprotective effect after 48 hours and 7 days of reperfusion and the effects of the treatment on the glial scar and regenerative events such as the generation of new progenitors in the subventricular zone and axonal sprouting at the edge of the damaged area.We show that meloxicam’s neuroprotective effects remained after 7 days of reperfusion even if its administration was restricted to the two first days after ischemia.Moreover,meloxicam treatment modulated glial scar reactivity,which matched with an increase in axonal sprouting.However,this treatment decreased the formation of neuronal progenitor cells.This study discusses the dual role of anti-inflammatory treatments after stro ke and encourages the careful analysis of both the neuroprotective and the regenerative effects in preclinical studies.

Electroacupuncture-attenuated ischemic brain injury increases insulin-like growth factor-1 expression in a rat model of focal cerebral ischemia

Acupuncture has recently gained popularity in many countries as an alternative and complementary therapeutic intervention. Previous studies have shown that changes in genes, proteins, and their metabolites were measureable during acupuncture for treatment of cerebral ischemia. Through the use of in situ hybridization and immunohistochemistry, the present study confirmed that electroacupuncture increased insulin-like growth factor-1 mRNA and protein expression in the corpus stfiatum following cerebral ischemia, reduced brain edema following middle cerebral artery occlusion reperfusion, and decreased infarct volume. Results suggested that electroacupuncture is effective in the relief of cerebral ischemia by increasing endogenous insulin-like growth factor-1 expression.

A feasible strategy for focal cerebral ischemiareperfusion injury: remote ischemic postconditioning

It is difficult to control the degree of ischemic postconditioning in the brain and other isch- emia-sensitive organs. Remote ischemic postconditioning could protect some ischemia-sensitive organs through measures on terminal organs. In this study, a focal cerebral ischemia-reperftlsion injury model was established using three cycles of remote ischernic postconditioning, each cycle consisted of 10-minute occlusion of the femoral artery and 10-minute opening. The results showed that, remote ischemic postconditioning significantly decreased the percentage of the in- farct area and attenuated brain edema. In addition, inflammatory nuclear factor-KB expression was significantly lower, while anti-apoptotic Bcl-2 expression was significantly elevated in the ce- rebral cortex on the ischemic side. Our findings indicate that remote ischemic postconditioning attenuates focal cerebral ischemia/reperfusion injury, and that the neuroprotective mechanism is mediated by an anti-apoptotic effect and reduction of the inflammatory response.

Changes of Nitric Oxide Synthase Activity in Penumbral and Core Area during Focal Cerebral Ischemia and Reperfusion in Rats

Objective:To study the changes of nitric oxide synthase(NOS)activity in penumbral and core area during focal cerebral ischemia and reperfusion,and to explore the therapeutic window of focal cerebral ischemia. Methods:The middle cerebral artery of rats was occluded for 15,30,60,90 and 120 min by an intraluminal filament respectively,and recirculation was instituted for 24 h.The changes of NOS activity in ischemic core area(parietal cortex and caudoputamen)and penumbral area (frontal cortex)were examined after focal cerebral ischemia and reperfusion using NADPH-d histochemistry technique.Results:The NOS activity of the ischemic penumbral area peaked at 60 min while the ischemic core area peaked at 30 min then declined at 90-120 min sharply.Conclusion:NOS takes part in cerebral ischemic damage during focal cerebral ischemia and reperfusion.The NOS activity of the ischemic penumbral area is different from the ischemic core area.The peak time of the penumbral area is delayed comparing with the core area.The data suggest that the best time to apply NOS inhibitor is within 30 min in ischemic core area, and 60 min in penumbral area.

Optimal electroacupuncture frequency for maintaining astrocyte structural integrity in cerebral ischemia

The astrocyte is a critical regulator of neuronal survival after ischemic brain injury. Electroacupuncture may be an effective therapy for cerebral ischemia, as electroacupuncture frequency can affect the structural integdty of astrocytes. In this study, a rat model of middle cerebral artery occlusion established using the modified thread embolism method was treated with electroacupuncture of the bilateral Quchi （Llll） and Zusanfi （ST36） at 15, 30, and 100 Hz frequencies. Behavioral testing, immunohistochemistry and electron microscopy were used to explore the effect of these electroacupuncture frequencies used on maintaining the structural integrity of ischemic brain tissue. Compared with the model and 100 Hz electroacupuncture groups the 15 and 30 Hz electroacupuncture groups displayed decreased neurological deficit scores, as evaluated by the ＂Longa＂ method, significantly increased glial fibrillary acidic protein expression, and alleviated ultrastructural damage of astrocytes at the edge of the infarct. Our experimental findings indicate that 15 and 30 Hz electroacupuncture intervention can favorably maintain the structural integrity of astrocytes and play a protective role in cerebral ischemic injury. Astrocyte structural integrity may be the mechanism underlying acupuncture production of ischemic tolerance

Acupuncture effects on serum myelin basic protein and remyelination following 30 minutes and 2 hours of ischemia in a rat model of cerebral ischemia-reperfusion injury

BACKGROUND： Acupuncture treatment on injured cerebral axons has shown to provide efficacy in clinical practice. It is unknown whether acupuncture produces therapeutic effects by protecting injured cerebral myelin in ischemic stroke. OBJECTIVE： To test whether acupuncture provides protection for injured cerebral myelin, based on quantitative data from cerebral ischemia-reperfusion rats, and to compare the effects of early and late acupuncture on serum myelin basic protein （MBP） content and remyelination of the ischemic internal capsule.DESIGN, TIME AND SETTING： A randomized, controlled experiment was performed at the Neurobiological Laboratory, Sichuan University from March 2005 to March 2006. MATERIALS： ＂Hua Tuo＂ Brand filiform needles were produced by the Medical Instrument Factory of Suzhou, China.METHODS： A total of 52 adult, healthy, male, Sprague Dawley rats were randomly assigned to four groups： control （n = 4）, model （n = 16）, early acupuncture （n = 16）, and late acupuncture （n = 16）. The focal cerebral ischemia-reperfusion model was established by middle cerebral artery occlusion in the right hemisphere using the modified thread embolism method in the latter three groups. Early and late acupuncture groups underwent acupuncture after ischemia for 30 minutes and 2 hours using the Xingnaokaiqiao needling method, respectively. Acupoints were ＂Neiguarf＇ （PC 6） and ＂Sanyinjiao＂ （SP 6） on the bilateral sides, as well as ＂Shuigou＇ （DU 26） and ＂Baihui＂ （DU 20） with stimulation for 1 minute at each acupoint. Acupuncture at all acupoints was performed two or three times while the needle was retained, once per day. No special handling was administered to the control clroup.MAIN OUTCOME MEASURES： For each group, remyelination of the internal capsule was observed by Pal-Weigert＇s myelin staining and serum MBP content was detected using enzyme-linked immunosorbent assay method on days 1,3, 5, and 7 following ischemia-reperfusion injury.RESULTS： Compared with the control group, massive demyelination of the internal capsule occurred, and serum MBP content increased in the model group （P 〈 0.05）. Compared with the model group, the extent of demyelination in the internal capsule was less distinct and serum MBP content was significantly less in the early and late acupuncture group （P 〈 0.01 ）. Compared with the late acupuncture group, serum MBP content reached a peak later and the peak value was less in the early acupuncture group. CONCLUSION： Results suggest that acupuncture exerts a protective effect on injured cerebral myelin in ischemia-reperfusion rats by reducing serum MBP content and promoting remyelination. The study also suggests that the effect of early acupuncture is superior to late acupuncture.

Neuroprotective effect of ischemic preconditioning in focal cerebral infarction: relationship with upregulation of vascular endothelial growth factor

Neuroprotection by ischemic preconditioning has been confirmed by many studies, but the precise mechanism remains unclear. In the present study, we performed cerebral ischemic pre- conditioning in rats by simulating a transient ischemic attack twice （each a 20-minute occlusion of the middle cerebral artery） before inducing focal cerebral infarction （2 hour occlusion-reper- fusion in the same artery）. We also explored the mechanism underlying the neuroprotective effect of ischemic preconditioning. Seven days after ocdusion-reperfusion, tetrazolium chloride staining and immunohistochemistry revealed that the infarct volume was significantly smaller in the group that underwent preconditioning than in the model group. Furthermore, vascular endothelial growth factor immunoreactivity was considerably greater in the hippocampal CA3 region of preconditioned rats than model rats. Our results suggest that the protective effects of ischemic preconditioning on focal cerebral infarction are associated with upregulation of vascu- lar endothelial growth factor.

银杏内酯对大鼠局灶性脑缺血的保护作用

目的 研究银杏内酯对大鼠局灶性脑缺血的作用。方法 选用中动脉阻塞 再灌模型观测对比脑缺血大鼠给药组和模型组的各项指标。结果 银杏内酯口服能使脑缺血大鼠的神经行为明显改善 ,脑梗塞面积和脑含水量显著降低 ;高、中、低三个剂量组与缺血模型组相比均有显著性差异。该药还能降低缺血后脑组织匀浆中的MDA、LD含量 ,提高SOD和GSH活性。脑组织病理切片也证实了该药对神经细胞的保护作用。结论 银杏内酯对大鼠局灶性脑缺血有保护作用。

大鼠局灶性脑缺血模型的定量分析

目的 :采用大脑中动脉阻塞 (MCAO)诱导大鼠局灶性脑缺血模型的方法 ,用计算机辅助技术定量分析脑损伤变化及药物保护作用。方法 :以不同 MCAO时间诱导脑缺血并再灌注 2 4 h后 ,观察神经功能缺失症状 ,并以计算机图像分析技术测定脑梗死体积、脑半球面积、皮层及纹状体神经元密度及白蛋白渗出 ;在缺血前后腹腔注射地塞米松 0 .1mg/ kg或尼莫地平 0 .4 mg/ kg,观察药物的保护作用。结果 :缺血 30 min和再灌注 2 4 h可发生神经功能缺失症状、梗死灶形成、缺血侧脑半球面积增加 11.4 %、神经元密度减少 36 .2 %、白蛋白渗出明显增加。地塞米松和尼莫地平可改善神经功能缺失症状 ,显著减小梗死体积 ,抑制缺血侧脑半球面积增加、神经元死亡和白蛋白渗出。结论 :缺血 30 min和再灌注 2 4 h是诱导局灶性脑缺血的合适条件 ,计算机辅助技术客观定量综合评价脑缺血损伤及药物作用是可行的方法。

脑缺血动物模型及其实验治疗学应用

脑缺血是指由于大脑特定部位的血流供应受阻所导致的血氧不足或脑缺氧,以致不能满足供能的需要,造成脑组织死亡或脑梗塞/缺血性中风。脑缺血的病理生理机制以及缺血性脑损伤后的神经修复是当今神经科学研究的热点之一。动物模型的成功复制为脑缺血的实验治疗学研究起了巨大的推动作用。本文就国内外已经建立的弥漫性脑缺血、局灶性脑缺血动物模型的方法学文献作系统综述,同时列举这些模型的优缺点及其在实验治疗学中的应用,为实验性神经保护药物的药效学筛选提供科学指导。

血管内尼龙线栓塞大鼠大脑中动脉局灶性脑缺血模型的改进

目的确立更规范统一的制作大鼠局灶性脑缺血模型方法,使脑梗死体积更加稳定。方法对24只大鼠使用液态硅胶涂层尼龙线栓塞大脑中动脉,分别缺血1,2,6和24h后再灌注24h,监测缺血侧局部脑血流,测定脑梗死体积及脑水肿程度。结果缺血后所有大鼠局部脑血流均降到缺血前基值的25%以下,TTC染色显示所有动物在缺血侧皮质和尾状核均有明显的梗死灶和缺血,缺血1 h组梗死体积与缺血2h以上组有显著性差异,缺血2h以上各组之间梗死体积无显著性差异;各组脑水肿程度无显著性差异。结论应用硅胶涂层尼龙线结合局部脑血流监测,缺血2h以上同时予以血流监测,可制作梗死体积稳定的大鼠局灶性脑缺血模型。

磁共振弥散/灌注加权成像确认局灶脑缺血半暗带的实验研究

目的 探讨超急性期确认局灶脑缺血半暗带的范围和演变规律。方法 用易卒中型肾血管性高血压大鼠(RHRSP)行左侧腔内线栓MCAO术 ,分别在闭塞 12h内的不同时间点及再灌注 48h后行T2 加权成像 (T2 WI)、磁共振弥散加权成像 (DWI)和磁共振灌注加权成像 (PWI)。将大鼠处死后行TTC染色 ,比较在闭塞不同的时间点上在两次T2 WI和DWI上病灶的演变和TTC染色上梗死灶的改变。结果 DWI在闭塞 30min时显示出确切的病灶 ,而T2 WI要在 3h以后才能显示出病灶 ;自 30min至 6h ,DWI所显示的病灶持续扩大 ,可逆性部分占首次DWI上病灶的百分比 (%RP)逐渐缩小 ,最终为负数 ;PWI在MCAO闭塞的即刻即在时间 信号强度曲线上表现为最大下降幅度的减小 ,复通后上升 5 0 %以上 ;半暗带部分水的表面弥散系数值 (ADC)为 (0 5 6± 0 0 2 )× 10 -5cm2 /s。结论 DWI能在超急性期 (3h以内 )显示出缺血病灶 ,根据梗死中心和梗死周边的ADC值的不同可以分辨出可逆性和不可逆性损伤的缺血组织 ;本模型的缺血半暗带存在的时间为6h。

局灶性脑缺血耐受和星形胶质细胞反应

目的 研究短暂性局灶性脑缺血预处理对永久性局灶性脑缺血的保护作用 ,及最佳预处理时间剂量 ,并探讨星形胶质细胞在脑缺血耐受中的反应。方法 采用开颅方法阻断大鼠大脑中动脉 ,通过观察大鼠脑梗死后神经功能损伤状况、脑梗死体积分析及病理形态学变化 ,评价不同的缺血预处理时间剂量 (10分钟、2 0分钟、30分钟 )对永久性局灶性脑缺血的保护作用。采用胶质纤维酸性蛋白 (GFAP)免疫组化法观察星形胶质细胞在脑缺血耐受中的反应。结果 与对照组相比 ,缺血预处理 2 0分钟未引起明显的神经元损伤 ,但使永久性局灶性脑缺血后神经功能损伤减轻 ,梗死体积明显减小 (P <0 .0 1)。免疫组化显示 ,2 0分钟缺血预处理组及重复缺血组星形胶质细胞在损伤预处理侧广泛激活。结论 2 0分钟局灶性脑缺血预处理能够有效诱导脑缺血耐受。星形胶质细胞的激活可能与脑缺血耐受中神经元的存活相关。

针药联合对局灶性脑缺血大鼠神经细胞功能的影响

目的探讨针药联合治疗脑梗死的疗效与机理。方法以热凝法阻断大鼠一侧大脑中动脉(McAo)造成局灶性脑缺血为实验模型。将动物随机分为4组:模型组、中药组、针刺组、针药结合组。观测各组缺血区脑组织c-fos蛋白表达48h之内的动态变化。结果3个治疗组均能明显增强c-fos蛋白的表达,其中针药结合组明显优于其它组。结论针药联合能明显提高缺血区c-fos蛋白的含量,改善神经细胞的应激能力。比单独应用中药或针刺更有效。

高压氧预处理减少局灶性脑缺血后泛素化蛋白聚集

目的探讨泛素-蛋白酶体系统在重复高压氧(HBO)预处理导致的脑缺血耐受中所起的作用。方法采用大脑中动脉阻闭(MCAO)制备大鼠局灶性脑缺血模型,将33只SD大鼠随机分为假手术组(Sham)组、MCAO组和HBO组,分别观察各组大鼠脑梗死灶的大小和神经功能学评分,并用免疫组织化学染色检测再灌注2h、24h时相点大鼠脑组织CA1区异常泛素化蛋白聚集的变化。结果 HBO组脑梗死容积小于MCAO组,差异有统计学意义(P<0.05),其神经功能学评分也明显优于MCAO组(P<0.05)。再灌注各时相点,HBO组泛素化蛋白聚集明显少于MCAO组(P<0.05)。结论高压氧预处理所诱导的脑缺血耐受的机制可能与泛素化蛋白聚集降低有关。

小鼠局灶性脑缺血模型的比较分析

小鼠局灶性脑缺血模型是研究缺血性脑血管病的重要工具,可以帮助我们更好地了解局灶性脑缺血的发病机制。本课题组对小鼠局灶性脑缺血模型中最常用的线栓插入法、开颅手术电凝闭塞法、光化学诱导法、栓子栓塞法分别进行综述介绍。

补阳还五汤对大鼠局灶性脑缺血损伤血脑屏障的影响

目的观察补阳还五汤对大鼠局灶性脑缺血损伤血脑屏障的保护作用,阐明该方抗脑缺血的机理。方法采用线栓法复制大鼠局灶性脑缺血模型。将SD大鼠随机分为假手术组、模型组和补阳还五汤组,造模后24 h给药,补阳还五汤组给予补阳还五汤灌胃,假手术组、模型组给予等量生理盐水灌胃。造模后7 d,评价各组大鼠神经功能并处死取材,四氮唑红染色观察大鼠脑组织梗死体积,HE染色观察大鼠脑微血管的一般形态,ELISA检测大鼠脑组织内基质金属蛋白酶(MMP)-9、MMP-2、血管内皮生长因子(VEGF)蛋白水平及血清中血管性血友病因子(vWF)的表达。结果与模型组比较,补阳还五汤组能显著改善神经功能行为评分,减少脑梗死体积,降低MMP-9、MMP-2、VEGF、vWF水平。病理观察结果显示,补阳还五汤组脑组织病理变化较模型组减轻。结论补阳还五汤对大鼠局灶性脑缺血具有保护作用,其作用可能与保护血脑屏障,抑制MMP-9、MMP-2、VEGF、vWF的表达有关。