水通道蛋白4在小鼠脑老化中的作用

水通道蛋白4(AQP4)主要分布在星形胶质细胞足突膜上,是脑内最重要的水通道亚型。已经发现,AQP4除参与调节脑内水平衡外,还参加学习记忆、脑外伤、脑缺血、脑肿瘤等一系列生理、病理过程。脑老化伴随着学习记忆下降,以及易发生脑缺血、脑肿瘤等老年相关性疾病,但AQP4在脑老化中的作用尚未见报道。目的观察AQP4在小鼠脑老化中的作用。方法对年轻(2～3个月)和老年(17～19个月)AQP4基因敲除小鼠(AQP4-/-)与野生型相应年龄的小鼠(AQP4+/+),观察AQP4基因敲除对老年小鼠自发活动、学习记忆、大体脑形态以及神经元、星形胶质细胞、小胶质细胞密度等的影响。结果老年小鼠自发活动减少,在穿梭箱被动避暗实验中,测试时进入暗箱的潜伏期明显短于年轻鼠,但AQP4+/+和AQP4-/-小鼠间无明显差异。甲苯胺蓝染色显示,老年小鼠皮层神经元密度(Ⅲ～Ⅳ层)显著低于年轻小鼠(P<0.05),海马CA1区厚度无明显差异,AQP4+/+和AQP4-/-小鼠间无明显差异。免疫组化显示,老年小鼠海马CA1的星形胶质细胞(GFAP阳性)数量明显高于年轻小鼠(P<0.01),而小胶质细胞数量在老年和年轻小鼠间无明显差异。免疫荧光显示,老年小鼠星形教胶质细胞的面积变小,而AQP4-/-小鼠的星形胶质细胞突起少而短、细胞面积明显小于AQP+/+小鼠(P<0.05),神经元和小胶质细胞形态无明显变化。结论 AQP4参与脑老化过程中的星形胶质细胞变化,而与运动、学习记忆相关的脑功能及神经元、小胶质细胞等脑结构变化无明显关系。     

星形胶质细胞-神经元的相关关系研究进展

星形胶质细胞在神经系统中的作用类似于调控者,信息传递者和区域划分者,更多时候它是感受神经元活动并作出相应反应,比如监控并摄入多余神经递质并把信息传递给小胶质细胞和少突胶质细胞,对这部分神经元进行选择,是否突触修剪、是否完成髓鞘化、使电传递稳定和筛选出优势传导通路。它类似于外周的纤维细胞,支持与营养作用是被动的。星形胶质细胞和神经元的关系已成为神经生物学中的热点。目前对星形胶质细胞和神经元相互作用主要包括能量代谢、突触可塑性和谷氨酸循环等。星形胶质细胞在一定应激条件下,由静息性星形胶质细胞向反应性星形胶质细胞转变;还可以通过特定的转录因子(例如Neuro D1,Sox2等)在体外以及体内转变为神经细胞。神经元分泌的Sonic hedgehog(Shh)、星形胶质细胞分泌的TGF-β1和Chrdl1等均相互影响彼此。神经连接蛋白(Neuroligin)如蛋白NL1,NL2和NL3的水平与星形胶质细胞的大小和形状成正向调节。因此,本文主要从星形胶质细胞和神经元之间的关系,包括相互作用、转化作用、分泌物和其蛋白相互影响等进行综述。     

星形胶质细胞与神经退行性疾病的相关性

星形胶质细胞是脑内数量最多的胶质细胞,其总体积占脑总体积20%-50%,星形胶质细胞与神经元之间存在广泛而复杂的信息传递,以直接、相互作用的方式与神经元发生联系,在神经系统的发育、突触传递、调控信息处理与信号传递、离子平衡、调节神经和突触的可塑性等方面都发挥重要作用。星形胶质细胞在损伤状态下可以快速反应,转变为反应性星形胶质细胞,此时其保护功能己经丧失,反而会加剧损伤。反应性星形胶质细胞并非为"全或无"概念,而是经历了从可逆的基因表达改变、正常结构区域内的细胞肥大,到永久性胶质瘢痕形成、组织结构改变这一系列变化的星形胶质细胞的总称。胶质瘢痕的增殖多伴随着胶质纤维酸性蛋白(GFAP)的表达增加,因此组织中GFAP升高是中枢神经系统对损伤作出反应的一个标志性信号。星形胶质细胞功能异常或退变严重破坏了星形胶质细胞-神经元之间的信息传递,导致神经元功能紊乱,诱发神经退行性疾病的产生,包括帕金森病、阿尔茨海默病、亨廷顿病及肌萎缩脊髓侧索硬化症。因此,星形胶质细胞绝不仅仅是神经退行性疾病中的配角,而是极其重要的参与者。阐明星形胶质细胞与神经退行性疾病的相关性可以为其有效药物的研发提供新的思路。     

星形胶质细胞与缺血性脑损伤

星形胶质细胞是脑中存在最多的细胞类型,能够为神经元提供代谢、营养支持及调节突触活性.脑缺血等病理状态下,反应性星形胶质细胞通过一系列生化过程的改变,诸如调节能量代谢、清除兴奋性氨基酸、抗氧化作用、分泌神经保护物质等发挥神经保护作用.缺血时星形胶质细胞内相关信号通路被激活,对细胞凋亡起调控作用.星形胶质细胞中相关酶、离子通道以及信号分子都可成为潜在的治疗靶点,通过药物干预,间接发挥神经保护作用.进一步阐明星形胶质细胞在缺血性脑损伤中的作用,可以为基于星形胶质细胞的新药研发提供思路.     

脑舒胶囊对阿尔茨海默病大鼠神经炎症损伤的保护

目的：研究脑舒胶囊对阿尔茨海默病（AD）大鼠神经炎症损伤的保护。方法：双侧脑室注射Aβ25～35复制AD大鼠模型;放射免疫分析法检测血清及海马组织IL-1β和IL-6的含量;RT-PCR法测定海马IL-6和IL-1β mRNA表达;免疫组织化学(SABC)法检测大鼠海马星形胶质细胞原纤维酸性蛋白(GFAP)的阳性细胞表达。结果：与假手术组比较,模型组大鼠血清及海马组织中IL-1β和IL-6含量明显增加（P＜0.05）;海马星形胶质细胞GFAP和海马IL-6,IL-1β mRNA表达显著上调（P＜0.01）。与模型组比较,0.72 g?kg-1脑舒胶囊可降低血清、海马组织IL-1β和IL-6含量（P＜0.05）和海马星形胶质细胞GFAP阳性和海马IL-6,IL-1β mRNA的表达（P＜0.05）。结论：脑舒胶囊可通过抑制星形胶质细胞的过度激活,从而抑制中枢慢性炎症级联反应对海马神经元的损伤。     

脑舒胶囊对阿尔茨海默病大鼠神经炎症损伤的保护

目的：研究脑舒胶囊对阿尔茨海默病（AD）大鼠神经炎症损伤的保护。方法：双侧脑室注射Aβ25～35复制AD大鼠模型;放射免疫分析法检测血清及海马组织IL-1β和IL-6的含量;RT-PCR法测定海马IL-6和IL-1β mRNA表达;免疫组织化学(SABC)法检测大鼠海马星形胶质细胞原纤维酸性蛋白(GFAP)的阳性细胞表达。结果：与假手术组比较,模型组大鼠血清及海马组织中IL-1β和IL-6含量明显增加（P＜0.05）;海马星形胶质细胞GFAP和海马IL-6,IL-1β mRNA表达显著上调（P＜0.01）。与模型组比较,0.72 g?kg-1脑舒胶囊可降低血清、海马组织IL-1β和IL-6含量（P＜0.05）和海马星形胶质细胞GFAP阳性和海马IL-6,IL-1β mRNA的表达（P＜0.05）。结论：脑舒胶囊可通过抑制星形胶质细胞的过度激活,从而抑制中枢慢性炎症级联反应对海马神经元的损伤。     

脑舒胶囊对阿尔茨海默病大鼠神经炎症损伤的保护

目的：研究脑舒胶囊对阿尔茨海默病（AD）大鼠神经炎症损伤的保护。方法：双侧脑室注射Aβ25～35复制AD大鼠模型；放射免疫分析法检测血清及海马组织IL-1β和IL-6的含量；RT-PCR法测定海马IL-6和IL-1β mRNA表达；免疫组织化学(SABC)法检测大鼠海马星形胶质细胞原纤维酸性蛋白(GFAP)的阳性细胞表达。结果：与假手术组比较，模型组大鼠血清及海马组织中IL-1β和IL-6含量明显增加（P＜0.05）；海马星形胶质细胞GFAP和海马IL-6，IL-1β mRNA表达显著上调（P＜0.01）。与模型组比较，0.72 g?kg-1脑舒胶囊可降低血清、海马组织IL-1β和IL-6含量（P＜0.05）和海马星形胶质细胞GFAP阳性和海马IL-6，IL-1β mRNA的表达（P＜0.05）。结论：脑舒胶囊可通过抑制星形胶质细胞的过度激活，从而抑制中枢慢性炎症级联反应对海马神经元的损伤。     

脑舒胶囊对阿尔茨海默病大鼠神经炎症损伤的保护

目的：研究脑舒胶囊对阿尔茨海默病（AD）大鼠神经炎症损伤的保护。方法：双侧脑室注射Aβ25～35复制AD大鼠模型；放射免疫分析法检测血清及海马组织IL-1β和IL-6的含量；RT-PCR法测定海马IL-6和IL-1β mRNA表达；免疫组织化学(SABC)法检测大鼠海马星形胶质细胞原纤维酸性蛋白(GFAP)的阳性细胞表达。结果：与假手术组比较，模型组大鼠血清及海马组织中IL-1β和IL-6含量明显增加（P＜0.05）；海马星形胶质细胞GFAP和海马IL-6，IL-1β mRNA表达显著上调（P＜0.01）。与模型组比较，0.72 g?kg-1脑舒胶囊可降低血清、海马组织IL-1β和IL-6含量（P＜0.05）和海马星形胶质细胞GFAP阳性和海马IL-6，IL-1β mRNA的表达（P＜0.05）。结论：脑舒胶囊可通过抑制星形胶质细胞的过度激活，从而抑制中枢慢性炎症级联反应对海马神经元的损伤。     

脑舒胶囊对阿尔茨海默病大鼠神经炎症损伤的保护

目的：研究脑舒胶囊对阿尔茨海默病（AD）大鼠神经炎症损伤的保护。方法：双侧脑室注射Aβ25～35复制AD大鼠模型；放射免疫分析法检测血清及海马组织IL-1β和IL-6的含量；RT-PCR法测定海马IL-6和IL-1β mRNA表达；免疫组织化学(SABC)法检测大鼠海马星形胶质细胞原纤维酸性蛋白(GFAP)的阳性细胞表达。结果：与假手术组比较，模型组大鼠血清及海马组织中IL-1β和IL-6含量明显增加（P＜0.05）；海马星形胶质细胞GFAP和海马IL-6，IL-1β mRNA表达显著上调（P＜0.01）。与模型组比较，0.72 g?kg-1脑舒胶囊可降低血清、海马组织IL-1β和IL-6含量（P＜0.05）和海马星形胶质细胞GFAP阳性和海马IL-6，IL-1β mRNA的表达（P＜0.05）。结论：脑舒胶囊可通过抑制星形胶质细胞的过度激活，从而抑制中枢慢性炎症级联反应对海马神经元的损伤。     

参乌胶囊对β-淀粉样肽大鼠模型脑内炎症反应的影响

目的:观察中药新复方参乌胶囊对Aβ25-35肽段海马注射大鼠模型脑内炎症反应的影响.方法:大鼠单侧(左侧)海马内注射Aβ25-35,用免疫组化方法观察海马内小胶质细胞和星形胶质细胞数量,放免法检测海马内炎性因子IL-1β和TNFα含量,用尼氏染色法检测海马神经元数量.结果:参乌胶囊灌胃给药2周,能够明显抑制Aβ模型大鼠海马内胶质细胞的活化状态,减少小胶质细胞和星形胶质细胞的数量和面积,并且减少炎性因子IL.1β和TNFα的产生,减轻神经元损伤.结论:参乌胶囊能够抑制Aβ引起的神经炎性反应,起到保护神经元的作用.     

Cerebral glucose metabolism in diabetes mellitus

The brain uses glucose as its primary fuel. Cerebral metabolism of glucose requires transport through the blood–brain barrier, glycolytic conversion to pyruvate, metabolism via the tricarboxylic acid cycle and ultimately oxidation to carbon dioxide and water for full provision of adenosine triphosphate (ATP) and its high-energy equivalents. When deprived of glucose, the brain becomes dysfunctional or can be even permanently damaged. Glucose is stored as glycogen within astrocytes with potential importance for tolerance of hypoglycemia. Glycogen may also be important for the metabolic response to somatosensory stimulation and coupling of blood flow and cellular metabolism. Uncontrolled diabetes has a variety of adverse effects upon brain metabolism and function. Many aspects of function that affect the brain may be indirectly linked to cerebral glucose metabolism. Neurotransmitter metabolism, cerebral blood flow, blood–brain barrier and microvascular function may all be affected to varying degrees by either hypoglycemia or uncontrolled diabetes mellitus.     

Cerebral glycogenolysis and glycolysis in malathion-treated hyperglycaemic animals

Treatment with malathion resulted in an increase in the level of blood glucose and lactate and reduced cerebral glycogen, 2 hr after its administration. The blood pyruvate level was not changed. The activities of glycogenolytic enzymes (glycogen phosphorylase and phosphoglucomutase) were increased significantly in the brain, whereas that of glucose-6-phosphatase remained unchanged. The activity of the glycolytic enzyme-hexokinase was increased significantly in malathion-treated animals, whereas those of the glucose-6-phosphate and lactate dehydrogenases were not significantly changed. The changes in enzyme activities may be a compensatory mechanism to provide energy in the form of glucose to cerebral tissue on account of stimulatory effects in malathion-treated animals.     

Changes in cerebral glycogenolysis and related enzymes in diazinon treated hyperglycaemic animals

Effect of diazinon (10,20 and 40 mg/kg, i.p.) on the level of blood glucose in rats was investigated. Hyperglycaemia peaked 2 h after i.p. treatment with 40 mg/kg diazinon. The cerebral acetylcholinesterase activity was significantly reduced. The blood level of pyruvic acid was unchanged while that of lactic acid was significantly increased. Convulsions and biochemical changes caused by diazinon (40 mg/kg) were prevented by diazepam injected immediately after diazinon. In diazinon-treated hyperglycaemic animals, the glycogen content of the brain was depleted, the activities of glycogen phosphorylase, phosphoglucomutase and hexokinase were significantly increased and the activity of glucose-6-phosphatase remained unchanged. Lactate dehydrogenase activity was also increased by treatment with diazinon. The induced changes may compensate for the energy requirement of stimulatory effects caused by diazinon.     

The model of stroke induced by microsphere embolism in rats

Cerebral infarction is induced by injecting 700-900 microspheres with a diameter of 50 microm into the right internal carotid artery of the rat. Approximately 82% of the rats with typical symptoms of stroke survived at fifteen hours after the injection of microspheres. Microsphere-induced cerebral embolism elicits the widespread formation of small emboli in the ipsilateral hemisphere and subsequent neuronal loss and/or the development of multiple infarct areas in the brain, particularly in the cortex, striatum, and hippocampus. Thus, this model is considered to mimic focal ischemia-induced human stroke or multi-infarct dementia. We have found that this model showed sustained decreases in cerebral blood flow and cerebral high-energy phosphates; accumulation of tissue lactate, glucose, and glycogen; changes in the activity of several enzymes in the tricarboxylic acid cycle; loss of mitochondrial phosphorylation activity; and decreases in neurotransmitters, acetylcholine, monoamines, and amino acids in the ipsilateral hemisphere. Accordingly, microsphere embolism is capable of inducing severe and sustained cerebral ischemia resulting in disturbances of the energy and neurotransmitter metabolism in the brain. Such ischemic damage leads to learning and memory dysfunction. This model provides useful information about the pathogenesis, prophylaxis, and therapeutics of cerebral ischemic diseases.     

Implications of astrocytes in neurovascular coupling

Normal brain function requires continuous supply of oxygen and glucose in a strict manner. The close spatial and temporal relationship between neural activity and cerebral blood flow (CBF) is termed as neurovascular coupling, which is dependent or not dependent on astrocytes. The increase in flow evoked by brain activity is mediated by the concerted action of multiple mediators that originate from different cells and act at different levels of the cerebral vasculature. More studies are needed for further understanding the precise mechanisms underlying neurovascular coupling, especially the implications of astrocytes.     

Effect of KC-404 on experimental cerebral infarction in rats

Experimental cerebral infarction accompanying altered cerebral energy metabolism and cerebral edema was produced in rats by injecting arachidonate into the left carotid artery. In the present study, the effects of 3-isobutyryl-2-isopropylpyrazolo [1,5-alpha]pyridine (KC-404) on these ischemic insults as well as on the regional cerebral blood flow (r-CBF) were studied. 1) Cerebral metabolism: On the 7th day of infarction, a significant decrease in ATP content and an increase in glucose content were observed, especially in the left hemisphere. There were no significant changes in lactate and pyruvate contents as compared with normal rat brain. Treatment with KC-404 (10 mg/kg, p.o.) once on the 7th day or twice on the 6th and 7th days of infarction caused a significant increase in ATP content and a decrease in lactate content. Increased content of glucose tended to be suppressed by KC-404. In normal rats, KC-404 (10 mg/kg, p.o.) caused slight but significant increases in cerebral ATP, glucose and pyruvate contents. 2) Cerebral edema: On the 4th day of infarction, significant increases in water content and Na+/K+ ratio and a decrease in K+ content were observed in the left hemisphere. Treatment with KC-404 (10 mg/kg, p.o.) for three preceding days showed a significant suppression of increased water content with a tendency to improve altered electrolyte levels. 3) r-CBF: KC-404 (0.05 mg/kg/min) infused i.v. for 15 min increased more markedly the r-CBF in the affected left hemisphere as compared with that in normal brain.(ABSTRACT TRUNCATED AT 250 WORDS)     

地高辛抗血清拮抗内洋地黄素介导的脑缺血再灌注损伤的实验研究

目的　观察脑缺血再灌注损伤时血清和脑组织内洋地黄素水平变化和内洋地黄素拮抗剂地高辛抗血清对脑缺血再灌注损伤的干预作用。方法　采用Kameyama’s的三动脉夹闭法制作双侧大脑半球缺血模型。SD大鼠 5 6只 ,随机分成 7组 ,每组 8只。假手术组 ,缺血再灌注模型组 ,阴性对照组 ,尼莫地平组 ,小剂量、中剂量、大剂量地高辛抗血清组。各组于再灌注 6 0min后取血分离血清 ,同时断头取脑制作脑匀浆和光镜标本。结果　脑缺血再灌注时 ,血清CK活性增高 ;脑组织SOD活性下降 ,MDA水平升高 ;脑组织和血清内洋地黄素水平明显升高 ;脑组织ATP酶活性下降 ;脑线粒体内总Ca2 + 水平升高 ,Mg2 + 水平下降 ;脑组织存在炎症性改变和片状坏死区 ,细胞层次不清 ,锥体细胞形态异常。地高辛抗血清能降低血清CK活性 ;拮抗缺血再灌注所致的脑组织SOD活性下降和MDA水平的升高 ;能降低脑组织内洋地黄素水平 ;大、中剂量地高辛抗血清组能明显提高脑组织ATP酶活性 ,拮抗缺血再灌注所致的脑组织线粒体内离子水平的异常 ;能减轻神经元细胞变性。结论　脑缺血再灌注时脑组织内洋地黄素水平升高 ,增高的内洋地黄素是介导脑缺血再灌注损伤的重要因子。地高辛抗血清通过拮抗内洋地黄素的作用而减轻脑损伤 ,对脑缺血再灌注损伤有防治作用     

Energy metabolism of the isolated perfused rat brain as influenced by anesthetics.

The isolated perfused rat brain was used for a comparative study of the effects of thiopental (0.2 mM), hexobarbital (0.2 mM), γ-hydroxybutyric acid (4 mM) and ketamine (0.05 mM) on cerebral energy metabolism. After a perfusion period of 30 min the brain levels of high-energy phosphates, as well as those of substrates and metabolites of the glycolytic pathway were measured spectrophotometrically. All drugs tested caused an increase in cerebral P-creatine. Furthermore, after perfusion with the barbiturates, or γ-hydroxybutyric acid, increased levels of glycogen and glucose, and decreased levels of pyruvate and lactate were measured. After ketamine perfusion, however, the glycogen and glucose levels tended to be diminished. Doubling the glucose concentration in the perfusion medium led to a marked increase in brain glucose, which after anesthesia with thiopental increased even further.     

Glucose metabolism disorder is a risk factor in ethanol exposure induced malformation in embryonic brain

Prenatal exposure to ethanol has been reported to cause developmental defects in the brain. During brain development, a sufficient energy source is deemed essential and glucose is regarded as the primary energy source for neurons. In this study, the impact of ethanol on embryonic malformation and cerebral glucose metabolism in developing embryo was investigated. Different doses of ethanol (0, 10, 20, 40 mg/egg) were administrated to chicken embryos after 36 h incubation. Embryonic brain weight was found significantly decreased. Moreover, we observed an obvious reduction of neurofilament expression in the central nervous system (CNS) by immunostaining assay. All the above indicated that ethanol exposure caused obvious CNS damages and resulted malformations in the developing brain. Mechanism research showed that cerebral glucose and lactic acid contents, activities of hexokinase, pyruvate kinase and lactic dehydrogenase were decreased dose dependently. Meanwhile, mRNA levels of glucose transporter 1, glucose transporter 3 and insulin-like growth factor I in the brain demonstrated a significant decrease in gene expression after ethanol exposure. These results suggested that glucose metabolism disorder is an important risk factor in ethanol exposure induced malformation in embryonic brain.     

参芎葡萄糖注射液对急性不完全性脑缺血的保护作用

目的研究参芎葡萄糖注射液对脑缺血的保护及治疗作用,为其临床应用提供科学依据。方法雄性SD大鼠随机分成6组:假手术组(等容量生理盐水),脑缺血模型组(等容量生理盐水),参芎葡萄糖注射液低、中、高剂量组(12、24、36 mg·kg-1),香丹注射液阳性对照组(3 mL·kg-1)。每日腹腔注射给药1次,连续给药3 d。检测脑指数及脑含水量、脑组织丙二醛(MDA)含量、乳酸脱氢酶(LDH)活力、观察脑组织形态学变化。结果参芎葡萄糖注射液能减轻缺血引起的脑细胞损伤,降低脑含水量及脑指数,降低缺血脑组织丙二醛含量及提高乳酸脱氢酶活力。结论参芎葡萄糖注射液对脑缺血有保护作用。