Hippocampal expression of synaptic structural proteins and phosphorylated cAMP response element-binding protein in a rat model of vascular dementia induced by chronic cerebral hypoperfusion

The present study established a rat model of vascular dementia induced by chronic cerebral hypoperfusion through permanent ligation of bilateral common carotid arteries.At 60 days after modeling,escape latency and swimming path length during hidden-platform acquisition training in Morris water maze significantly increased in the model group.In addition,the number of accurate crossings over the original platform significantly decreased,hippocampal CA1 synaptophysin and growth-associated protein 43 expression significantly decreased,cAMP response element-binding protein expression remained unchanged,and phosphorylated cAMP response element-binding protein expression significantly decreased.Results suggested that abnormal expression of hippocampal synaptic structural protein and cAMP response element-binding protein phosphorylation played a role in cognitive impairment following chronic cerebral hypoperfusion.     

Estrogen intervention in microvascular morphology and choline acetyltransferase expression in rat hippocampal neurons in chronic cerebral ischemia

We observed dynamic changes in microvessels and a protective effect of estrogen on chronic cerebral ischemia ovariectomized rat models established through permanent occlusion of bilateral carotid arteries at 7,14 and 21 days.The results revealed that estrogen improved microvasculature in the hippocampus of chronic cerebral ischemic rats,upregulated Bcl-2 protein expression,downregulated Bax protein expression,increased choline acetyltransferase expression in hippocampal cholinergic neurons,and suppressed hippocampal neuronal apoptosis.These findings indicate that estrogen can protect hippocampal neurons in rats with chronic cerebral ischemia.     

Telomerase expression in the glial scar of rats with spinal cord injury

A rat model of spinal cord injury was established using the weight drop method. A cavity formed 14 days following spinal cord injury, and compact scar tissue formed by 56 days. Enzyme-linked immunosorbent assay and polymerase chain reaction enzyme-linked immunosorbent assay results demonstrated that glial fibrillary acidic protein and telomerase expression increased gradually after injury, peaked at 28 days, and then gradually decreased. Spearman rank correlation showed a positive correlation between glial fibrillary acidic protein expression and telomerase expression in the glial scar. These results suggest that telomerase promotes glial scar formation.     

Scorpion ethanol extract and valproic acid effects on hippocampal glial fibrillary acidic protein expression in a rat model of chronic-kindling epilepsy induced by lithium chloride-pilocarpine

The present study analyzed the effects of ethanol extracts of scorpion on epilepsy prevention and hippocampal expression of glial fibrillary acidic protein in a lithium chloride-pilocarpine epileptic rat model. Results were subsequently compared with valproic acid. Results showed gradually- increased hippocampal glial fibrillary acidic protein expression following model establishment; glial fibrillary acidic protein mRNA expression was significantly increased at 3 days, reached a peak at 7 days, and then gradually decreased thereafter. Ethanol extracts of scorpion doses of 580 and 1 160 mg/kg, as well as 120 mg/kg valproic acid, led to a decreased number of glial fibrillary acidic protein-positive cells and glial fibrillary acidic protein mRNA expression, as well as decreased seizure grades and frequency of spontaneously recurrent seizures. The effects of 1 160 mg/kg ethanol extracts of scorpion were equal to those of 120 mg/kg valproic acid. These results suggested that the anti-epileptic effect of ethanol extracts of scorpion were associated with decreased hippocampal glial fibrillary acidic protein expression in a rat model of lithium chloride-pilocarpine induced epilepsy.     

Puerarin decreases hypoxia inducible factor-1 alpha in the hippocampus of vascular dementia rats

In this study, a rat vascular dementia model was established by permanent bilateral common carotid arterial occlusion. Rats were intraperitoneally injected with puerarin 3 days before modeling, for 45 successive days. Results demonstrated that in treated animals hippocampal structures were clear, nerve cells arranged neatly, and cytoplasm was rich in Nissl bodies. The number of cells positive for hypoxia inducible factor-1 alpha, erythropoietin and endothelial nitric oxide synthase was reduced; and the learning and memory abilities of rats were significantly improved. Our experimental findings indicate that puerarin can significantly improve learning and memory in a vascular dementia model, and that the underlying mechanism may be associated with the regulation of the expression of hypoxia inducible factor-1 alpha.     

戊四氮点燃慢性癫痫大鼠海马及颞叶皮质γ-氨基丁酸转运体1及胶质纤维酸性蛋白的表达

BACKGROUND： Gamma-aminobutyric acid transporter plays an important role in gamma-aminobutyric acid metabolism, and is highly associated with epilepsy seizures. Pathologically, astrocytes release active substances that alter neuronal excitability, and it has been demonstrated that astrocytes play a role in epileptic seizures. OBJECTIVE： To observe changes in gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression in the hippocampus and cortex of the temporal lobe in rats with pentylenetetrazol-induced chronic epilepsy. DESIGN, TIME AND SETTING： Randomized, controlled, animal experiment was performed at the Department of Neurobiology, Third Military University of Chinese PLA between January 2006 and December 2007. MATERIALS： Pentylenetetrazol was purchased from Sigma, USA; rabbit anti-rat gammaaminobutyric acid transporter 1 and glial fibrillary acidic protein were from Chemicon, USA. METHODS： A total of 40 Sprague Dawley rats were divided into model and control groups. Rat models of chronic epilepsy were created by pentylenetetrazol kindling, and were subdivided into 3-, 7-, and 14-day kindling subgroups. MAIN OUTCOME MEASURES： Gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression, as well as the number of positive cells in the hippocampus and cortex of temporal lobe of rats, were determined by immunohistochemistry and Western blot analyses. RESULTS： Compared with the control group, the number of gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein -positive cells in the hippocampus and cortex of rats with pentylenetetrazol-induced epilepsy significantly increased, gamma-aminobutyric acid transporter 1 and glial fibrillary acidic protein expression increased after 3 days of kindling, reached a peak on day 7, and remained at elevated levels at day 14 （P〈 0.05）. CONCLUSION： Astrocytic activation and gamma-aminobutyric acid transporter 1 overexpression may contribute to pentylenetetrazol-induced epilepsy.     

Effects of electroacupuncture on the expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in the hippocampus of rats with vascular dementia

This study investigated the mechanism underlying electroacupuncture therapy for vascular dementia through electroacupuncture at the acupoints of Baihui (DU20), Dazhui (DU14), and bilateral Shenshu (BL23) in a rat model of vascular dementia produced by bilateral middle cerebral artery occlusion. Morris water maze test showed that electroacupuncture improved the learning ability of vascular dementia rats. Western blot assay revealed that the expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in vascular dementia rats was significantly increased after electroacupuncture, compared with the model group that was not treated with acupuncture. The average escape latency was also shortened after electroacupuncture, and escape strategies in the spatial probe test improved from edge and random searches, to linear and trending swim pathways. The experimental findings indicate that electroacupuncture improves learning and memory ability by up-regulating expression of p70 ribosomal protein S6 kinase and ribosomal protein S6 in the hippocampus of vascular dementia rats.     

Mechanism underlying the protective effect of Kaixin Jieyu Fang on vascular depression following cerebral white matter damage简

The Chinese compound Kaixin fieyu Fang can be used to treat vascular depression; however, the underlying mechanism remains unclear. This study established a rat model of chronic cerebral ischemia-caused white matter damage by ligation of the bilateral common carotid arteries. Rats received daily intragastric administration of a suspension of Kaixin ]ieyu Fang powder. After 3, 7 and 21 days of treatment, the degree of white matter damage in the cerebral ischemia rat model was alleviated, Bcl-2 protein and mRNA expression in brain tissue increased, and Bax protein and mRNA expression decreased. These results indicate that Kaixin Jieyu Fang can alleviate cere- bral white matter damage, and the underlying mechanism is associated with regulation of Bcl-2/ Bax protein and mRNA expression, which is one of possible mechanism behind the protective effect of Kaixin Jieyu Fang against vascular depression.     

Cortical neurogenesis in adult rats after ischemic brain injury: most new neurons fail to mature

The present study examines the hypothesis that endogenous neural progenitor cells isolated from the neocortex of ischemic brain can differentiate into neurons or glial cells and contribute to neural regeneration. We performed middle cerebral artery occlusion to establish a model of cerebral ischemia/reperfusion injury in adult rats. Immunohistochemical staining of the cortex 1, 3, 7, 14 or 28 days after injury revealed that neural progenitor cells double-positive for nestin and sox-2 appeared in the injured cortex 1 and 3 days post-injury, and were also positive for glial fibrillary acidic protein. New neurons were labeled using bromodeoxyuridine and different stages of maturity were identified using doublecortin, microtubule-associated protein 2 and neuronal nuclei antigen immunohistochemistry. Immature new neurons coexpressing doublecortin and bromodeoxyuridine were observed in the cortex at 3 and 7 days post-injury, and semi-mature and mature new neurons double-positive for microtubule-associated protein 2 and bromodeoxyuridine were found at 14 days post-injury. A few mature new neurons coexpressing neuronal nuclei antigen and bromodeoxyuridine were observed in the injured cortex 28 days post-injury. Glial fibrillary acidic protein/bromodeoxyuridine double-positive astrocytes were also found in the injured cortex. Our findings suggest that neural progenitor cells are present in the damaged cortex of adult rats with cerebral ischemic brain injury, and that they differentiate into astrocytes and immature neurons, but most neurons fail to reach the mature stage.     

Resveratrol improves cognition and reduces oxidative stress in rats with vascular dementia

Resveratrol possesses beneficial biological effects,which include anti-oxidant,anti-inflammatory and anti-carcinogenic properties.Recently,resveratrol has been shown to exhibit neuroprotective effects in models of Parkinson’s disease,cerebral ischemia and Alzheimer’s disease.However,its effects on vascular dementia remain unclear.The present study established a rat model of vascular dementia using permanent bilateral common carotid artery occlusion.At 8-12 weeks after model induction,rats were intragastrically administered 25 mg/kg resveratrol daily.Our results found that resveratrol shortened the escape latency and escape distances in the Morris water maze,and prolonged the time spent percentage and swimming distance percentage in the target quadrant during the probe test,indicating that resveratrol improved learning and memory ability in vascular dementia rats.Further experiments found that resveratrol decreased malonyldialdehyde levels,and increased superoxide dismutase activity and glutathione levels in the hippocampus and cerebral cortex of vascular dementia rats.These results confirmed that the neuroprotective effects of resveratrol on vascular dementia were associated with its anti-oxidant properties.     

甘露醇对骨髓间充质干细胞治疗血管性痴呆大鼠行为学及海马胆碱能系统的影响

目的 探讨甘露醇对骨髓间充质干细胞(BMSCs)移植治疗血管性痴呆(VD)大鼠行为学及海马胆碱能系统活性的影响.方法 体外全骨髓培养结合细胞贴壁法培养大鼠BMSCs.采用双侧颈总动脉结扎法制备VD模型.将大鼠随机分为4组:(1)甘露醇预处理BMSCs组:造模4w后,先进行尾静脉注射20%甘露醇,10～30min后,再尾静脉注射BMSCs;(2)BMSCs组:造模4w后,经尾静脉注射等量BMSCs;(3)培养基组:造模4w后,经尾静脉注射等量BMSCs基础培养基;(4)假手术组:不进行任何干预.BMSCs移植4w后进行Morris水迷宫试验和大鼠海马内胆碱乙酰转移酶(ChAT)和乙酰胆碱酯酶(AChE)活性检测.结果 甘露醇预处理BMSCs组的ChAT和AChE活性均比BMSCs组、培养基组有明显提高(P<0.05),同时其行为学亦较BMSCs组、培养基组有明显改善(P<0.05).结论 甘露醇预处理后进行静脉注射移植BMSCs,使VD大鼠模型海马胆碱能系统的活性明显增强,并进一步改善VD大鼠的学习与记忆能力.     

Panax ginseng extract attenuates neuronal injury and cognitive deficits in rats with vascular dementia induced by chronic cerebral hypoperfusion

Panax ginseng is a slow-growing perennial plant.Panax ginseng extract has numerous biological activities,including antitumor,anti-inflammatory and antistress activities.Panax ginseng extract also has a cognition-enhancing effect in rats with alcohol-induced memory impairment.In this study,we partially occluded the bilateral carotid arteries in the rat to induce chronic cerebral hypoperfusion,a wellknown model of vascular dementia.The rats were then intragastrically administered 50 or 100 mg/kg Panax ginseng extract.Morris water maze and balance beam tests were used to evaluate memory deficits and motor function,respectively.Protein quantity was used to evaluate cholinergic neurons.Immunofluorescence staining was used to assess the number of glial fibrillary acidic protein-positive cells.Western blot assay was used to evaluate protein levels of vascular endothelial growth factor,basic fibroblast growth factor,Bcl-2 and Bax.Treatment with Panax ginseng extract for 8 weeks significantly improved behavioral function and increased neuronal density and VEGF and b FGF protein expression in the hippocampal CA3 area.Furthermore,Panax ginseng extract reduced the number of glial fibrillary acidic protein-immunoreactive cells,and it decreased apoptosis by upregulating Bcl-2 and downregulating Bax protein expression.The effect of Panax ginseng extract was dose-dependent and similar to that of nimodipine,a commonly used drug for the treatment of vascular dementia.These findings suggest that Panax ginseng extract is neuroprotective against vascular dementia induced by chronic cerebral hypoperfusion,and therefore might have therapeutic potential for preventing and treating the disease.     

Glial activation and white matter changes in the rat brain induced by chronic cerebral hypoperfusion: an immunohistochemical study

Activation of glial cells and white matter changes (rarefaction of the white matter) induced in the rat brain by permanent bilateral occlusion of the commom carotid arteries were immunohistochemically investigated up to 90 days. One day after ligation of the arteries, expression of the major histocompatibility complex (MHC) class I antigen in microglia increased in the white matter including the optic nerve, optic tract, corpus callosum, internal capsule, anterior commissure and traversing fiber bundles of the caudoputamen. After 3 days of occlusion, MHC class I antigen was still elevated and in addition MHC class II antigen and leukocyte common antigen were up-regulated in the microglia in these same regions. Astroglia, labeled with glial fibrillary acidic protein, increased in number in these regions after 7 days of occlusion. A few lymphocytes, labeled with CD4 or CD8 antibodies, were scattered in the neural parenchyma 1 h after occlusion. Activation of glial cells and infiltration of lymphocytes persisted after 90 days of occlusion in the white matter and the retinofugal pathway. However, cellular activation and infiltration in microinfarcts of the gray matter was less extensive and was substantially diminished 30 days after occlusion. The white matter changes were most intense in the optic nerve and optic tract, moderate in the medial part of the corpus callosum, internal capsule and anterior commissure, and slight in the fiber bundles of the caudoputamen. These results indicated that chronic cerebral hypoperfusion induced glial activation preferentially in the white matter. This activation seemed to be an early indicator of the subsequent changes in the white matter.     

Possible mechanisms of lycopene amelioration of learning and memory impairment in rats with vascular dementia

Oxidative stress is involved in the pathogenesis of vascular dementia. Studies have shown that lycopene can significantly inhibit oxidative stress; therefore, we hypothesized that lycopene can reduce the level of oxidative stress in vascular dementia. A vascular dementia model was established by permanent bilateral ligation of common carotid arteries. The dosage groups were treated with lycopene(50, 100 and 200 mg/kg) every other day for 2 months. Rats without bilateral carotid artery ligation were prepared as a sham group. To test the ability of learning and memory, the Morris water maze was used to detect the average escape latency and the change of search strategy. Hematoxylin-eosin staining was used to observe changes of hippocampal neurons. The levels of oxidative stress factors, superoxide dismutase and malondialdehyde, were measured in the hippocampus by biochemical detection. The levels of reactive oxygen species in the hippocampus were observed by dihydroethidium staining. The distribution and expression of oxidative stress related protein, neuron-restrictive silencer factor, in hippocampal neurons were detected by immunofluorescence histochemistry and western blot assays. After 2 months of drug administration,(1) in the model group, the average escape latency was longer than that of the sham group, and the proportion of straight and tend tactics was lower than that of the sham group, and the hippocampal neurons were irregularly arranged and the cytoplasm was hyperchromatic.(2) The levels of reactive oxygen species and malondialdehyde in the hippocampus of the model group rats were increased, and the activity of superoxide dismutase was decreased.(3) Lycopene(50, 100 and 200 mg/kg) intervention improved the above changes, and the lycopene 100 mg/kg group showed the most significant improvement effect.(4) Neuron-restrictive silencer factor expression in the hippocampus was lower in the sham group and the lycopene 100 mg/kg group than in the model group.(5) The above data indicate that lycopene 100 mg/kg could protect against the learning-memory ability impairment of vascular dementia rats. The protective mechanism was achieved by inhibiting oxidative stress in the hippocampus. The experiment was approved by the Animal Ethics Committee of Fujian Medical University, China(approval No. 2014-025) in June 2014.     

Nestin expression persists in astrocytes of organotypic slice cultures from rat cortex

Nestin is an intermediate filament protein typical for neural precursor cells that is down-regulated in the post-natal rodent brain. Re-expression of nestin has been observed in reactive astrocytes after injury. In this study, organotypic slice cultures from rat cortex were examined for expression of nestin and glial fibrillary acidic protein between 2 and 8 weeks in culture. Immunoreactivity for nestin and glial fibrillary acidic protein was seen in astrocytes which persisted throughout the observation period. Immunofluorescence double labeling showed widespread co-localization of nestin and glial fibrillary acidic protein. Image analysis revealed that levels of nestin-immunoreactivity plateaued after 5 weeks in culture. By comparison nestin immunoreactivity was absent from glial cells of the cortex in mature rats. These immunohistochemical findings of a persistent expression of nestin in glial cells of organotypic slice culture of the rat cortex indicate a different time course of glial maturation in vitro. This difference could be related to the altered trophic stimulation in vitro; differences in neuronal maturation, activity or survival; slow degeneration of the vasculature; or intrinsic properties of astrocytes.     

盐酸多奈哌齐对血管性痴呆小鼠海马神经细胞神经元蛋白激酶C表达变化的影响

目的探讨盐酸多奈哌齐对血管性痴呆（Vascular dementia,VD）小鼠海马神经元蛋白激酶C（protein kinase C,PKC）变化的影响。方法将3月龄雄性昆明小鼠随机分为假手术组、模型组、多奈哌齐治疗组。采用双侧颈总动脉结扎,反复缺血-再灌注制备VD模型,药物治疗30d。术后第29、30天,分别进行跳台试验和水迷宫试验观察各组小鼠行为学改变。采用免疫组织化学法观察各组海马CA1区神经元PKC表达的变化。结果药物治疗组小鼠学习、记忆成绩较模型组明显改善（P〈0.05）。模型组PKC免疫反应阳性神经元平均光密度值为（0.2730±0.0709）,与假手术组（0.3206±0.0642）和药物组（0.3036±0.0688）相比均显著降低（P〈0.05）,而药物组与假手术组间无明显差别（P〉0.05）。结论反复缺血-再灌注导致VD小鼠海马神经元PKC表达减少;多奈哌齐通过抑制中枢神经系统中乙酰胆碱的降解,可增加VD小鼠海马神经元PKC表达,从而改善VD小鼠学习、记忆能力,推测此也是该药物改善VD小鼠学习、记忆障碍的一个重要环节。     

慢性前脑缺血致血管性痴呆大鼠不同脑区MAP-2的经时变化研究

目的研究微管结合蛋白-2(MAP-2)在慢性前脑缺血致血管性痴呆大鼠额、颞叶皮质和海马区的经时变化。方法采用双侧颈总动脉永久结扎方法制备慢性前脑缺血致VD大鼠动物模型;采用免疫组织化学方法检测痴呆鼠不同脑区MAP-2的经时变化情况;采用同济大学研制的HPIAS-1000高清晰彩色病理图文分析系统对不同脑区MAP-2阳性信号的面积密度进行分析。结果实验发现痴呆大鼠不同脑区MAP-2的表达随时间变化。缺血1个月、2个月、4个月后MAP-2的表达阳性面积逐渐减少,与对照组相比有统计学意义。从形态学变化角度来说,1个月时MAP-2轻度变化,提示为可逆性损伤。随着缺血时间的延长,MAP-2免疫组化染色越来越淡。至4个月时,MAP-2免疫组化染色基本消失,提示为不可逆损伤。结论慢性持续性脑血流量下降致MAP-2的改变在VD的病理生理过程中起重要作用。     

Differential expression of Musashi1 and nestin in the adult rat hippocampus after ischemia

Both nestin and the neural RNA-binding protein Musashi1 (Msi1) are expressed in neural stem cells in the subventricular zone. Neurogenesis in the hippocampus has received much attention, so we evaluated the expression of Msi1 and nestin in the adult rat hippocampus after transient forebrain ischemia. Both Msi1 and nestin were induced in the reactive astrocytes after ischemia, especially in the CA1 region, until 35 days after ischemia. Induction of both molecules suggested that reactive astrocytes might have immature characteristics. In the subgranular zone (SGZ) of the hippocampal dentate gyrus, Msi1-positive cells formed clusters after ischemia. These cells were labeled by bromodeoxyuridine (BrdU) but did not express glial fibrillary acidic protein. In contrast, very few nestin-positive cells were labeled by BrdU. Our results suggest that neuronal progenitor cells in the SGZ expressed Msi1 but not nestin.