芸香苷对慢性脑低灌注大鼠认知功能障碍和脑损伤的神经保护作用

目的:研究芸香苷对慢性脑低灌注导致大鼠认知功能障碍和脑损伤的影响。方法:采用双侧颈总动脉结扎法(bilateral common carotid artery occlusion,BCCAO)建立慢性脑低灌注大鼠模型,随机分为4组(n=10):生理盐水治疗模型组、芸香苷治疗模型组、生理盐水治疗假手术组、芸香苷治疗假手术组;连续腹腔注射芸香苷和生理盐水共12周。采用Morris水迷宫评定大鼠学习和记忆能力。采用分光光度法检测脑组织中枢胆碱能相关指标和氧化应激指标。应用免疫组织化学和El ISA方法检测脑组织炎症反应。采用Nissl染色法检测脑组织神经元缺失。结果:芸香苷治疗模型组大鼠的逃脱潜伏期较生理盐水治疗模型组明显减少(P0.01)。与生理盐水治疗模型组相比,芸香苷治疗后显著提高了BCCAO大鼠脑组织中ACh水平(P0.01)和Ch AT活性(P0.01),并降低了ACh E活性(P0.01)。与生理盐水治疗模型组相比,芸香苷治疗模型组显著增加了大鼠脑组织中SOD活性(P0.01)和GPX活性(P0.01),降低了MDA水平(P0.01)和蛋白质羰基化合物水平(P0.01)。芸香苷治疗模型组大鼠海马区GFAP-免疫阳性星型胶质细胞(P0.01)和Iba1-免疫阳性小胶质细胞(P0.01)面积百分比较生理盐水治疗模型组显著减少。芸香苷治疗模型组大鼠海马区正常神经元的数量较生理盐水治疗模型组大鼠显著增加(P0.01)。结论:芸香苷可改善慢性脑低灌注引起的大鼠认知功能障碍和脑损伤。     

Improvement of Cognitive Deficit and Neuronal Damage in Rats with Chronic Cerebral Ischemia via Relative Long-term Inhibition of Rho-kinase

(1) The role of activation of Rho-kinase in the pathogenesis of cognitive deficit and neuronal damage caused by chronic global ischemia is not clear. In this study, hydroxyfasudil, a Rho-kinase inhibitor, was found to improve the learning and memory performance significantly in rats with ischemia induced by chronic cerebral hypoperfusion after permanent bilateral carotid artery ligation (BCAL). This was observed by the administration of hydroxyfasudil (1 mg/kg or 10 mg/kg, once per day for 30 days) to ischemic rats and the measurements of escape latency and time spent in the target quadrant among the ischemic, sham, and ischemic plus hydroxyfasudil rats by the method of Morris water maze. (2) In electrophysiological study, hydroxyfasudil abolished the inhibition of long-term potentiation (LTP) in rats with ischemia. Morphologically, it also markedly reduced pathological changes such as neuronal cells loss and nuclei shrinkage in cortex and hippocampus of ischemic rats. Biochemical analysis showed that the inhibition of Rho-kinase by hydroxyfasudil reduced the amount of MDA and increased the activities of SOD and GPx in ischemic rats that had increased MDA and decreased SOD and GPx activities. (3) To explore mechanism (s) of the beneficial effects of hydroxyfasudil in ischemia, we performed immunohistochemistry and RT-PCR analyses of NMDA NR2B subunit and for the first time found that hydroxyfasudil increased the expression of NR2B in cortex and hippocampus at both protein and mRNA levels. (4) Taken together, our data further support the notion that the inhibition of Rho-kinase provides neuroprotective effects in cerebral ischemia.     

Chronic Cerebral Hypoperfusion Induces Transient Reversible Monoaminergic Changes in the Rat Brain

Chronic restriction of cerebral blood flow in hypoperfused Wistar rats has been proposed as a new model of cerebrovascular-type dementia. Using this model, we have investigated central monoaminergic neuronal systems that are closely related to higher brain function. Monoamine and monoamine-metabolite levels were determined, as relative monoaminergic markers, at 1 day and 1,3,6 and 12 weeks after the bilateral occlusion of common carotid arteries. Dopaminergic changes in the frontal cortex and striatum were observed in hypoperfused rats at 1–3 weeks following occlusion. Serotonergic changes were recognized at four brain regions examined (frontal cortex, hippocampus, striatum and thalamus+midbrain). In particular, the immediate enhancement of serotonin turnover in the striatum appeared to influence the reaction to the acute ischemic attack such as vasoconstriction produced by hypoperfusion. Our findings suggest that chronic cerebral hypoperfusion induces transient reversible changes in central monoaminergic neuronal function within three weeks of ligation of carotid arteries. This time interval seems to represent a turning point in the process of chronic cerebral hypoperfusion-induced progressive brain injury.     

AT1 Receptor Blocker Candesartan-induced Attenuation of Brain Injury of Rats Subjected to Chronic Cerebral Hypoperfusion

One of common pathophysiological states associated with central nervous system is chronic cerebral hypoperfusion (CH) that frequently occurs in conditions such as vascular dementia and Alzheimer’s disease. Long term blockage of angiotensin II type 1 (AT₁) receptor provides protection from ischemia induced injury of brain as well as reduction of cerebrovascular inflammation. Examining effect of the blockage on reduced glutathione (GSH), ascorbic acid (AA), and lipid peroxidation were of purpose in the present study. Modeling CH, rats were subjected to permanent occlusion of common carotid arteries bilaterally. AT₁ receptor antagonist, candesartan, was given daily for 14 days after surgery. CH caused a significant increase in lipid peroxidation and decrease in GSH content of cerebral hippocampal tissue with no change in AA level. Candesartan (0.5 mg/kg, oral) not only reduced lipid peroxidation but also restored GSH significantly besides elevating AA and improving histopathological alterations. In conclusion, long term AT₁ receptor blockage may be considered as novel therapeutic approach for protection from damage associated with CH. Underlying mechanism(s) may in part be related to suppressing oxidative stress and preserving brain antioxidant capacity.     

小檗碱对慢性低灌注脑损伤小鼠神经保护作用的机制研究

摘要 目的：探究小檗碱对慢性低灌注脑损伤小鼠神经保护作用的机制。方法：采用单侧颈总动脉永久性结扎（Unilateral Common Carotid Artery Occlusion UCCAO）方法建立慢性脑低灌注小鼠模型,随机分为 5组（n=10）,分别为假手术组、模型组、按小檗碱剂量不同分为低剂量组、中剂量组和高剂量组,连续灌胃给药21天。采用走平横木实验和Morris水迷宫评定小鼠精细运动能力和学习记忆能力。采用ElISA 方法检测小鼠海马和皮质的炎症指标IL-1β、NLRP3和 TNF-α。结果：与模型组比较,小檗碱中剂量和小檗碱高剂量组精细运动能力明显提高（P<0.01）,小檗碱低剂量无显著性变化（P>0.05）。与模型组比较,小檗碱中剂量和小檗碱高剂量组认知能力明显提高（P<0.01）,小檗碱低剂量无显著性变化（P>0.05）。与模型组比较,小檗碱中剂量和小檗碱高剂量组小鼠海马区和皮质区TNF-a、IL-1β、NLRP3的表达显著减少,小檗碱低剂量组IL-1β无显著性变化（P>0.05）。结论：小檗碱可提高慢性低灌注脑损伤小鼠的精细运动能力并对其认知功能障碍具有改善作用,同时减少神经炎症反应,具有神经保护作用。     

PI3K/Akt Signal Pathway Involved in the Cognitive Impairment Caused by Chronic Cerebral Hypoperfusion in Rats

Chronic cerebral hypoperfusion (CCH) is a common pathophysiological state that usually occurs in conditions such as vascular dementia and Alzheimer''s disease, both of which are characterized by cognitive impairment. In previous studies we found that learning capacity and memory were gradually impaired with CCH, which altered the expression of synaptophysin, microtubule associated protein-2, growth associated protein-43, brain-derived neurotrophic factor, nerve growth factor, N-methyl-D-aspartate receptor subunit 1, cAMP response element-binding protein and tau hyperphosphorylation in the hippocampus. However, the molecular basis of cognitive impairment in CCH remains obscure. Here we explore the hypothesis that the phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) signal pathway is involved in this type of cognitive impairment. In order to determine if the expression of PI3K, Akt and phosphorylated Akt (p-Akt) proteins are altered at different stages of CCH with differing levels of cognitive impairment. we performed permanent, bilateral occlusion of the common carotid arteries (2-VO) to induce CCH. Adult male SD rats were randomly divided into sham-operated group, 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group. Behavior tests were utilized to assess cognitive abilities, while western blots were utilized to evaluate protein expression. Rats in the 2-VO groups spent less time exploring novel objects than those in the sham-operated group, and the discrimination ratio of the 2-VO 8 weeks group and the sham-operated group were higher than chance (0.50). Escape latencies in the Morris water maze task in the 2-VO 1 week group were longer than those in the sham-operated group on day 4 and day 5, while escape latencies in the 2-VO 4 weeks group were longer than those in the sham-operated group from day 3 to day 5. Escape latencies in 2-VO 8 weeks group were longer than those in the sham-operated group from day 2 to day 5. NE (northeast) square swimming times in the 2-VO 1 week group, 2-VO 4 weeks group and 2-VO 8 weeks group were shorter than that in the sham-operated group. Western blotting showed that the PI3K expression in the 2-VO 1 week group was lower than that in sham-operated group, while p-Akt expression in the 2-VO 8 weeks group was higher than that in the sham-operated group. There was a linear relationship between the PI3K expression and the discrimination ratio, as well as a linear relationship between the PI3K and NE square swimming time. Thus, we propose that the PI3K/Akt signal pathway is an important cell pathway that is associated with the cognitive impairment following CCH.     

吡拉西坦联合胞磷胆碱对急性脑梗死认知功能和神经功能的影响

目的:研究吡拉西坦联合胞磷胆碱对急性脑梗死认知功能和神经功能的影响。方法:选择2014年1月～2018年1月我院的150例急性脑梗死患者,随机分为两组。对照组采用吡拉西坦治疗,观察组采用吡拉西坦联合胞磷胆碱治疗。采用神经功能缺损程度(National Institutes of Health Stroke Scale,NIHSS)、析蒙特利尔认知评估量表(Montreal cognitive assessment scale,Mo CA)和日常生活能力(Activities of daily living,ADL)评分量表,比较两组治疗前后神经功能、认识功能和日常生活能力变化。结果:观察组基本治愈15例,显效30例,有效26例,无效4例,恶化1例,总有效率为94.67%,明显高于对照组(P0.05);治疗后,两组的ADL和Mo CA评分明显升高,神经功能缺损量表(National Institutes of Health Stroke Scale,NHISS)评分明显降低,且观察组的ADL、Mo CA和NHISS评分明显优于对照组(均P0.05);治疗后,两组的血清细胞凋亡蛋白酶-3(cysteinyl aspartate specific proteinase-3,Caspase-3)和低氧诱导因子-1α(Hypoxia-inducible factor 1α,HIF-1α)水平均明显降低,且观察组明显低于对照组(均P0.05);对照组发生干呕1例(1.33%),恶心2例(2.67%),头痛1例(1.33%),头晕1例(1.33%);观察组发生干呕1例(1.33%),恶心1例(1.33%),头痛1例(1.33%),出血1例(1.33%);两组无明显差异(P0.05)。结论:吡拉西坦联合胞磷胆碱能改善急性脑梗死的认知功能和神经功能,其机制可能与调节细胞诱导因子Caspase-3和HIF-1α的表达水平相关。     

东莨菪碱慢性给药大鼠作为老龄相关记忆损害模型的探索

目的对东莨菪碱慢性给药大鼠能否作为老龄相关记忆损害模型进行探索。方法14只1月龄SD大鼠随机分为对照组和东莨菪碱模型组。东莨菪碱模型组大鼠皮下注射东莨菪碱2mg kg,2次日,正常对照组予等量生理盐水,连续21d。然后利用Morris水迷宫(MWM)参照记忆试验进行行为学测试;神经元的特殊染色及电子显微镜技术,观察大鼠海马CA1、CA3区锥体细胞数、超微结构的改变以及突触可塑性变化。结果东莨菪碱组大鼠隐匿平台搜索实验成绩有一定损害;两组大鼠空间探索次数差异无显著性(P>0.05)。两组间海马CA1、CA3区锥体细胞数差异无显著性(P>0.05)。两组大鼠锥体细胞胞体超微结构无差异,但两组大鼠CA1区神经元突触超微结构有轻微变化。结论东莨菪碱慢性给药对大鼠学习记忆能力有一定损害,但对长时记忆无明显影响;对海马神经元结构无明显损害,对神经元突触可塑性有轻微影响。此种动物模型可能不是理想的老年性痴呆或老年相关记忆损害模型。     

Hypermethioninemia Increases Cerebral Acetylcholinesterase Activity and Impairs Memory in Rats

In the present study we investigated the effect of chronic hypermethioninemia on rat performance in the Morris water maze task, as well as on acetylcholinesterase (AChE) activity in rat cerebral cortex. For chronic treatment, rats received subcutaneous injections of methionine (1.34–2.68 μmol/g of body weight), twice a day, from the 6th to the 28th day of age; control rats received the same volume of saline solution. Groups of rats were killed 3 h, 12 h or 30 days after the last injection of methionine to AChE assay and another group was left to recover until the 60th day of life to assess the effect of early methionine administration on reference and working spatial memory of rats. AChE activity was also determined after behavioral task. Results showed that chronic treatment with methionine did not alter reference memory when compared to saline-treated animals. In the working memory task, we observed a significant days effect with significant differences between control and methionine-treated animals. Chronic hypermethioninemia significantly increased AChE activity at 3 h, 12 h or 30 days after the last injection of methionine, as well as before or after behavioral test. The effect of acute hypermethioninemia on AChE was also evaluated. For acute treatment, 29-day-old rats received one single injection of methionine (2.68 μmol/g of body weight) or saline and were killed 1, 3 or 12 h later. Results showed that acute administration of methionine did not alter cerebral cortex AChE activity. Our findings suggest that chronic experimental hypermethioninemia caused cognitive dysfunction and an increase of AChE activity that might be related, at least in part, to the neurological problems presented by hypermethioninemic patients.     

大鼠血管性痴呆模型海马组织中线粒体的变化

目的:观察血管性痴呆模型(Vascular dementia,VD)大鼠海马组织内线粒体超微结构、线粒体膜电位与空间学习记忆能力的变化。方法:健康成年雄性Wistar大鼠30只,随机分为假手术组(SHAM)和血管性痴呆(VD)组,每组15只。VD组行双侧颈总动脉结扎手术制备血管性痴呆动物模型,SHAM组手术步骤同VD组,但不结扎颈总动脉。于术后第29天起行Morris水迷宫测试大鼠空间学习记忆功能,第1-5天为定位航行试验,评估大鼠空间学习能力,第6天进行空间探索试验,评估大鼠空间记忆功能。采用透射电镜技术、流式细胞学技术分别检测大鼠海马组织线粒体形态和功能变化。结果:与SHAM组相比,血管性痴呆模型组大鼠Morris水迷宫试验中逃避潜伏期明显延长(P0.01),在目标象限中停留时间显著缩短(P0.01),空间学习记忆能力受损,血管性痴呆模型组大鼠海马组织线粒体超微结构有明显损伤,线粒体膜电位明显下降(P0.01)。结论:线粒体损伤是血管性痴呆空间学习记忆功能障碍的重要机制之一。     

慢性脑低灌注大鼠焦虑样行为与海马区域炎性细胞因子水平的相关性分析

目的:分析慢性脑低灌注(CCH)大鼠模型焦虑样行为和海马和血清炎性细胞因子水平的相关性。方法:将成年雄性Sprague-Dawley(SD)大鼠(200-220 g)分为两组(假手术(sham)和双侧颈总动脉结扎(BCCAO)组,每组N=40),分别给予BCCAO或者假手术。造模4周后,通过旷场实验和高架十字迷宫测试大鼠焦虑样行为;间接免疫荧光(Iba1和GFAP染色)和酶联免疫吸附实验(ELISA)分别测定海马CA1区胶质细胞激活和血清及海马区域白细胞介素-6(IL-6)、肿瘤坏死因子-α(TNF-α)、细胞粘附分子-1(ICAM-1)和血管细胞粘附分子-1(VCAM-1))水平。结果:旷场实验结果表明相比sham组,BCCAO组总穿行距离、中央区穿行距离和停留时间明显增多(P<0.05),高架十字迷宫实验中BCCAO组开臂停留时间和访问次数明显增加(P<0.05),闭臂停留时间显著缩短(P<0.05)。另外,相比sham组,BCCAO组大鼠海马CA1区胶质细胞明显激活,海马以及血清中炎性因子的表达水平均显著上调。Pearson相关性分析显示海马区域而非血清ICAM-1和VCAM-1水平与CCH大鼠焦虑样行为(中央区和开臂的停留时间)呈显著正相关(P<0.05)。结论:海马区域ICAM-1和VCAM-1升高与CCH大鼠焦虑样行为显著相关,可能参与CCH慢性期焦虑样行为的发生。     

Quantifying Cognitive Decrements Caused by Cranial Radiotherapy

With the exception of survival, cognitive impairment stemming from the clinical management of cancer is a major factor dictating therapeutic outcome. For many patients afflicted with CNS and non-CNS malignancies, radiotherapy and chemotherapy offer the best options for disease control. These treatments however come at a cost, and nearly all cancer survivors (~11 million in the US alone as of 2006) incur some risk for developing cognitive dysfunction, with the most severe cases found in patients subjected to cranial radiotherapy (~200,000/yr) for the control of primary and metastatic brain tumors¹. Particularly problematic are pediatric cases, whose long-term survival plagued with marked cognitive decrements results in significant socioeconomic burdens². To date, there are still no satisfactory solutions to this significant clinical problem.We have addressed this serious health concern using transplanted stem cells to combat radiation-induced cognitive decline in athymic rats subjected to cranial irradiation³. Details of the stereotaxic irradiation and the in vitro culturing and transplantation of human neural stem cells (hNSCs) can be found in our companion paper (Acharya et al., JoVE reference). Following irradiation and transplantation surgery, rats are then assessed for changes in cognition, grafted cell survival and expression of differentiation-specific markers 1 and 4-months after irradiation. To critically evaluate the success or failure of any potential intervention designed to ameliorate radiation-induced cognitive sequelae, a rigorous series of quantitative cognitive tasks must be performed. To accomplish this, we subject our animals to a suite of cognitive testing paradigms including novel place recognition, water maze, elevated plus maze and fear conditioning, in order to quantify hippocampal and non-hippocampal learning and memory. We have demonstrated the utility of these tests for quantifying specific types of cognitive decrements in irradiated animals, and used them to show that animals engrafted with hNSCs exhibit significant improvements in cognitive function³.The cognitive benefits derived from engrafted human stem cells suggest that similar strategies may one day provide much needed clinical recourse to cancer survivors suffering from impaired cognition. Accordingly, we have provided written and visual documentation of the critical steps used in our cognitive testing paradigms to facilitate the translation of our promising results into the clinic.     

High-Frequency rTMS Improves Cognitive Function by Regulating Synaptic Plasticity in Cerebral Ischemic Rats

Neurochemical Research - Poststroke cognitive impairment (PSCI) is one of the most severe sequelae of stroke and lacks effective treatment. Previous studies have shown that high-frequency...     

Melatonin Improves Memory Deficits in Rats with Cerebral Hypoperfusion,Possibly, Through Decreasing the Expression of Small-Conductance Ca2+-Activated K+ Channels

Neurochemical Research - This study investigated the expression pattern, regulation of expression, and the role of hippocampal small-conductance Ca2+-activated K+ (SK) channels in memory deficits...     

血管性痴呆动物模型制作方法的改良

目的对大鼠血管性痴呆双侧颈总动脉永久性结扎模型（permanent bilateral common carotid arteryocclusion,2VO）进行改良,以提高模型动物存活率。方法采取改良造模方法（间隔7d分2次结扎双侧颈总动脉）和传统的2VO方法（同时结扎双侧颈总动脉）建立血管性痴呆模型,观察并比较2种方法大鼠的存活率、学习记忆能力改变及病理形态学变化。结果术后7 d,改良模型组动物存活率（86.7%）明显高于传统模型组（40.0%）（P〈0.05）。术后8 w与12 w,与假手术组比较,两种方法模型组逃避潜伏期均明显延长（P〈0.05）,而改良法与传统法造模组之间相比较无显著性差异。HE染色显示：改良法与传统法造模组的大鼠海马区神经元有相似程度的明显变性、坏死和凋亡。结论 2VO改良造模法是降低大鼠血管性痴呆模型动物死亡率的成功方法,值得进一步研究、推广。     

芪丹通脉片对大鼠慢性脑缺血损伤大鼠学习记忆的影响

目的:研究芪丹通脉片对慢性脑缺血所致学习记忆障碍的治疗作用及其可能机制。方法:采用双侧颈动脉结扎方法复制慢性脑缺血模型。将健康雄性SD大鼠随机分为空白对照组、模型组、假手术组、芪丹通脉片低剂量组、芪丹通脉片中剂量组、芪丹通脉片高剂量组、阳性对照尼莫地平组,应用Morris水迷宫检测大鼠学习记忆能力,HE染色观察海马神经元形态学改变。结果:与对照组比较,模型组大鼠可见显著学习记忆障碍,并可见海马神经元呈现出典型的神经病理性改变,海马区神经细胞数量减少、固缩等改变。芪丹通脉片可显著减轻慢性脑缺血所致学习记忆能力,并减其轻海马神经元损伤,且有显著剂量依赖性。结论:本实验证实芪丹通脉片可显著减轻慢性脑缺血所致学习记忆障碍,其可能机制是通过减轻海马损伤来改善学习记忆能力。     

褪黑素对慢性脑低灌注大鼠海马齿状回区神经再生的影响

目的:研究褪黑素在慢性脑低灌注(Chronic Cerebral Hypoperfusion,CCH)大鼠模型中对神经再生的作用及机制。方法:使用双侧颈总动脉结扎法(bilateral common carotid artery occlusion,BCCAO)制备大鼠CCH模型,80只雄性的SD大鼠随机分为4组,每组20只:生理盐水治疗假手术组(Sham组)、生理盐水治疗模型组(BCCAO组)、褪黑素(5 mg/kg)治疗模型组(MT1组)、褪黑素(10 mg/kg)治疗模型组(MT2组)。连续腹腔注射褪黑素或生理盐水共4周。利用挖掘实验评估大鼠行为学;使用HE染色观察神经细胞变性及坏死;采取尼氏染色法观察大鼠海马齿状回区神经元损伤情况;利用免疫荧光法测定神经元特异核蛋白(NeuN)、胶质纤维酸性蛋白(Ki67)、双皮质素(DCX)的表达;利用Western Blot法测定大鼠海马区脑源性神经营养因子(BDNF)、酪氨酸激酶B受体(TrkB)含量的表达。结果:和Sham组相比,BCCAO组大鼠挖掘能力明显下降(P0.01),HE和尼氏染色出现神经细胞大量坏死、数量减少,NeuN阳性细胞数增加(P0.01)、Ki67/DCX阳性细胞数无明显增加(P0.05),BDNF、TrkB蛋白含量明显低于假手术组(P0.01)。与BCCAO组相比,MT1组和MT2组大鼠挖掘能力均明显改善(P0.01),HE和尼氏染色显示神经元存活数量增加,MT1组NeuN阳性细胞数增加(P0.05)、Ki67/DCX阳性细胞数增加(P0.05),MT2组NeuN、Ki67/DCX阳性细胞数明显增加(P0.01),MT1组及MT2组BDNF、TrkB蛋白含量明显增加(P0.01)。结论:褪黑素促进了CCH大鼠海马齿状回区神经再生和行为学的改变,其机制可能与激活BDNF-TrkB信号转导通路有关。