不同年龄脑出血大鼠海马齿状回神经干细胞增殖与分化差异的比较

BACKGROUND:Cerebral hemorrhage can activate the proliferation and differentiation of neural stem cells in the dentate gyrus of the hippocampus. Through continuous differentiation and proliferation, endogenous neural stem cells can gradually replace aging and damaged neurons, thus protecting the brain structure. OBJECTIVE:To compare the difference of the proliferation and differentiation of neural stem cells in the dentate gyrus of the hippocampus of rats with different ages. METHODS:Ninety-six adult rats and 96 aged rats were randomly divided into normal group (n=18 per group), sham operation group (n=12 per group) and cerebral hemorrhage group (model group, n=66 per group), respectively. Cerebral hemorrhage models were made in the two model groups in which, the rats were subjected to cerebral hemorrhage for 6, 24, 48, 72 hours and 7 days, respectively. Then, brain tissues were collected to measure brain water content. BrdU/NeuN and BrdU/GFAP double staining were performed at 3, 7, 14, 21, 28 days after surgery to calculate the number of positive cells. RESULTS AND CONCLUSION:For both adult and aged rats, the brain water content was significantly higher than that in the normal group and sham operation group (P < 0.05), while in the normal and sham operation groups, the brain water content was significantly lower in the aged rats than the adult rats (P  < 0.05). The number of bilateral BrdU-positive cells in the adult and aged model groups was significantly higher than that in the corresponding normal and sham operation groups (P  < 0.05), and moreover, the positive cell number at the hemorrhage side was significantly higher than that at the opposite side (P < 0.05). In addition, the number of BrdU-positive cells at the hemorrhage side in the adult rats was significantly higher than that in the aged rats at different time after cerebral hemorrhage (P  < 0.05). Results from immunohistochemical double staining showed that the BrdU/NeuN and BrdU/GFAP expression in the hippocampal dentate gyrus of adult rats with cerebral hemorrhage was significantly higher than that of normal adult rats. All these experimental results show that there are a few neural stem cells proliferating in the hippocampal dentate gyrus of normal rats, and the proliferation ability is stronger in the adult rats than the aged rats. Cerebral hemorrhage can significantly strengthen the proliferation of neural stem cells in the dentate gyrus in the adult rats compared with the aged rats.     

Intracerebroventricular infusion of insulin-like growth factor-I ameliorates the age-related decline in hippocampal neurogenesis.

The dentate gyrus of the hippocampus is one of few regions in the adult mammalian brain characterized by ongoing neurogenesis. Significantly, recent studies indicate that the rate of neurogenesis in the hippocampus declines with age, perhaps contributing to age-related cognitive changes. Although a variety of factors may influence the addition of new neurons in the adult dentate gyrus, the mechanisms responsible for the age-related reduction remain to be established. Insulin-like growth factor-I (IGF-I) is one promising candidate to regulate neurogenesis in the adult and aging brain since it influences neuronal production during development and since, like the rate of neurogenesis, it decreases with age. In the current study, we used bromodeoxyuridine labeling and multilabel immunofluorescence to assess age-related changes in neuronal production in the dentate gyrus of adult Brown Norway x Fischer 344 rats. In addition, we investigated the relationship between changes in neurogenesis and the age-dependent reduction in IGF-I by evaluating the effect of i.c.v. infusion of IGF-I on neurogenesis in the senescent dentate gyrus. The analyses revealed an age-dependent reduction in the number of newly generated cells in the adult dentate subgranular proliferative zone and, in addition, a 60% reduction in the differentiation of newborn cells into neurons. Restoration of IGF-I levels in senescent rats significantly restored neurogenesis through an approximately three-fold increase in neuronal production.The results of this study suggest that IGF-I may be an important regulator of neurogenesis in the adult and aging hippocampus and that an age-related decline in IGF-I-dependent neurogenesis could contribute to age-related cognitive changes.     

神经干细胞与BDNF联合治疗对Alzheimer病鼠海马突触素表达的影响

本研究目的在于探讨神经干细胞(NSCs)与脑源性神经营养因子(BDNF)联合应用对老年性痴呆鼠海马突触素(SYH)表达的影响。切断成年老年性痴呆模型鼠左侧穹窿海马伞,基底前脑行神经干细胞移植(移植组),或同时持续侧脑室内注射BDNF(联合组),4周后用免疫组织化学染色结合图像分析技术对各组大鼠海马突触素进行校正光密度(COD)测定。结果显示:损伤组损伤侧海马CA1区辐射层和分子层SYH的COD分别下降到正常组的54.6%和59.0%(P<0.01);移植组COD恢复到正常组的68.9%和67.9%,与损伤组相比差异显著(P<0.05);联合组COD恢复到正常组的82.9%和81.0%,与移植组相比差异显著(P<0.05)。以上结果提示:神经干细胞移植与BDNF注射联合治疗,对老年性痴呆模型鼠海马CA1辐射层和齿状回分子层突触素的表达有明显促进作用,且联合治疗效果比单纯神经干细胞移植效果好。     

切割穹窿海马伞大鼠海马内BLBP的表达变化

为了观察切割大鼠右侧穹窿海马伞后,切割侧与正常侧海马齿状回内脑脂结合蛋白(BLBP)的表达变化,本研究应用Western blot和免疫组织化学方法检测双侧海马内BLBP蛋白表达水平的变化,以及海马齿状回门区和颗粒下层中BLBP免疫阳性细胞数和灰度值。结果显示:正常大鼠双侧海马各区和颗粒下层细胞BLBP仅有微量表达,切割穹窿海马伞后第1 d双侧差异不明显;3 d时切割侧颗粒下层阳性细胞及染色深度较正常侧加深;5 d时切割侧颗粒下层阳性细胞数量明显增多,染色较深,并达到最高水平;7 d后BLBP免疫阳性细胞的数量和染色深度开始降低,14 d时接近正常侧水平。而切割后3、5 d时双侧门区BLBP免疫阳性细胞的数量差异不大,但切割侧染色较深,7 d后也逐渐降低,14 d时降至正常侧水平。上述结果提示,切割穹窿海马伞阻断了隔区与海马齿状回的纤维联系后,可引起海马齿状回门区和颗粒下层BLBP表达增强,可能引发了放射状胶质细胞的增殖和激活,构成的支架有助于神经干细胞的迁移和向神经元的分化。     

Hippocampal neuron and synaptophysin-positive bouton number in aging C57BL/6 mice

A loss of hippocampal neurons and synapses had been considered a hallmark of normal aging and, furthermore, to be a substrate of age-related learning and memory deficits. Recent stereological studies in humans have shown that only a relatively minor neuron loss occurs with aging and that this loss is restricted to specific brain regions, including hippocampal subregions. Here, we investigate these age-related changes in C57BL/6J mice, one of the most commonly used laboratory mouse strains. Twenty-five mice (groups at 2, 14, and 28–31 months of age) were assessed for Morris water-maze performance, and modern stereological techniques were used to estimate total neuron and synaptophysin-positive bouton number in hippocampal subregions at the light microscopic level. Results revealed that performance in the water maze was largely maintained with aging. No age-related decline was observed in number of dentate gyrus granule cells or CA1 pyramidal cells. In addition, no age-related change in number of synaptophysin-positive boutons was observed in the molecular layer of the dentate gyrus or CA1 region of hippocampus. We observed a significant correlation between dentate gyrus synaptophysin-positive bouton number and water-maze performance. These results demonstrate that C57BL/6J mice do not exhibit major age-related deficits in spatial learning or hippocampal structure, providing a baseline for further study of mouse brain aging.     

Increased dentate neurogenesis after grafting of glial restricted progenitors or neural stem cells in the aging hippocampus

Neurogenesis in the dentate gyrus (DG) declines severely by middle age, potentially because of age-related changes in the DG microenvironment. We hypothesize that providing fresh glial restricted progenitors (GRPs) or neural stem cells (NSCs) to the aging hippocampus via grafting enriches the DG microenvironment and thereby stimulates the production of new granule cells from endogenous NSCs. The GRPs isolated from the spinal cords of embryonic day 13.5 transgenic F344 rats expressing human alkaline phosphatase gene and NSCs isolated from embryonic day 9 caudal neural tubes of Sox-2:EGFP transgenic mice were expanded in vitro and grafted into the hippocampi of middle-aged (12 months old) F344 rats. Both types of grafts survived well, and grafted NSCs in addition migrated to all layers of the hippocampus. Phenotypic characterization revealed that both GRPs and NSCs differentiated predominantly into astrocytes and oligodendrocytic progenitors. Neuronal differentiation of graft-derived cells was mostly absent except in the dentate subgranular zone (SGZ), where some of the migrated NSCs but not GRPs differentiated into neurons. Analyses of the numbers of newly born neurons in the DG using 5'-bromodeoxyuridine and/or doublecortin assays, however, demonstrated considerably increased dentate neurogenesis in animals receiving grafts of GRPs or NSCs in comparison with both na?ve controls and animals receiving sham-grafting surgery. Thus, both GRPs and NSCs survive well, differentiate predominantly into glia, and stimulate the endogenous NSCs in the SGZ to produce more new dentate granule cells following grafting into the aging hippocampus. Grafting of GRPs or NSCs therefore provides an attractive approach for improving neurogenesis in the aging hippocampus. Disclosure of potential conflicts of interest is found at the end of this article.     

异氟醚麻醉抑制海马齿状回神经干细胞的增殖及分化

背景：异氟醚由于起效快、苏醒迅速、无积蓄等优点在儿科手术也逐渐被推广使用,然而其安全性还需要进一步观察。 目的：观察异氟醚麻醉对新生大鼠海马齿状回神经干细胞增殖及神经元分化的影响。 方法：将大鼠随机分为异氟醚组和对照组,分别予以异氟醚吸入麻醉和仅吸入空气。分别在给药前及停止给约后对动物予以5-溴脱氧球苷(BrdU)腹腔注射,第2次注射后24 h处死大鼠,获得脑组织,检测BrdU+和脑内神经源性分化因子表达情况。 结果与结论：停止麻醉处理之后进行血糖以及动脉血气检测,发现异氟醚组大鼠PaCO₂出现轻度上升,pH值出现轻微下降,而PaO₂、BE、SaO₂以及血糖水平则均未出现改变。与对照组相比,异氟醚组经异氟醚麻醉之后,未出现明显的缺氧表现,包括紫绀和呼吸抑制等。大鼠海马齿状回神经干细胞大多分布在门区,异氟醚组的BrdU阳性细胞数少于对照组(P < 0.05)。两组大鼠海马齿状回存在大量新生细胞表达NeuroD,门区NeuroD+/BrdU+阳性细胞数明显高于颗粒细胞下区,且异氟醚组显著高于对照组(P < 0.05)。结果证实,异氟醚麻醉会对新生大鼠海马齿状回神经干细胞增殖及神经元分化产生一定的影响,抑制其增殖,并促进其神经元分化。     

Cell Cycle Regulation During Neurogenesis in the Embryonic and Adult Brain

Throughout the development of the central nervous system, neural crest cells and the primary neural stem cells originate several non-neuronal and neuronal cell types. Undifferentiated stem cells exist in the adult brain, mainly in the dentate gyrus of the hippocampus and in the subventricular zone of the lateral ventricles, and can produce new neurons, participating in brain plasticity and tissue regeneration. Neurogenesis in the embryonic and adult brain occurs under the control of intrinsic and extrinsic factors. However, the mechanisms, by which cell cycle components control neural stem cell proliferation and consequently neurogenesis, still lack further investigation. We discuss here recent knowledge obtained on cell cycle components as key regulators of neural stem and progenitor cell proliferation and differentiation in the embryonic and adult brain.     

Age-related effects on hippocampal precursor cell subpopulations and neurogenesis

Hippocampal neurogenesis continuously declines in the aging brain but only little is known about age-related alterations in the subgranular zone (SGZ) of the dentate gyrus which accommodates different subpopulations of precursor cells. Here, we examined the age-related effects on total number and proliferation rate of distinct precursor cell populations in the dentate gyrus of 3 and 16 months old transgenic pNestin-GFP mice. Following a single injection of bromodeoxyuridine (BrdU) we observed a significant reduction of all proliferating precursor subtypes in aged mice compared to young controls. Stereological analysis further revealed that this decreased proliferation was not only caused by a general reduction in total number of precursor subtypes but also by a subtype-specific alteration of the proliferation rate. Whereas radial glia-like and early neuronal precursor cells demonstrate decreased proliferation rates, no difference was found for doublecortin-positive precursors. Additional long-term experiments further revealed that these age-related alterations in the proliferative zone were accompanied by a strongly decreased neurogenesis while hippocampal function was not impaired.     

大鼠室管膜下区和齿状回神经前体细胞增殖的衰老性变化

为了观察大鼠脑内神经前体细胞增殖的增龄性变化、探讨其在脑老化机制中的作用 ,本研究取不同年龄的大鼠经腹腔注射 Brd U标记处于增殖状态的神经前体细胞 ,用抗 Brd U抗体进行免疫组化反应 ,镜下观察脑内神经前体细胞的分布 ,并计数作定量分析。结果发现 ,各年龄组的室管膜下区及齿状回颗粒下层有 Brd U阳性细胞分布 ;上述各部位 Brd U阳性细胞数和标记率均呈明显的增龄性下降 ,幼年组和青年组之间 ,以及青年组和老年组之间的差异均有非常显著性意义 (P<0 .0 1)。结果表明 ,神经前体细胞的增殖能力随衰老而明显下降。这可能与衰老脑的神经元补偿能力及神经可塑性降低有关     

Antisense Noggin oligodeoxynucleotide administration decreases cell proliferation in the dentate gyrus of adult rats

The dentate gyrus of the hippocampus is one of few regions in the adult mammalian brain characterized by ongoing neurogenesis. It has been demonstrated that Noggin antagonizes bone morphogenetic protein-4 (BMP4) to create a niche for subventricular zone neurogenesis. We previously demonstrated that Noggin and BMP4 showed strong expression in the proliferative subgranular layer of the dentate gyrus in adult rats. To examine the action of Noggin on cell proliferation in the dentate gyrus of adult rats, we administered antisense oligodeoxynucleotide (ASODN) to Noggin by continuous infusion into the lateral ventricle of rats. Antisense-infused rats displayed significant reduction in number of bromodeoxyuridine (BrdU) labeled cells in the dentate gyrus. This indicated that endogenous Noggin activity is important for naturally occurring cell proliferation in the dentate gyrus, and perhaps neurogenesis, and is one of the many factors involved in its regulation.     

Insulin-like growth factor 1 reduces age-related disorders induced by prenatal stress in female rats

Stress during the prenatal period can induce permanent abnormalities in adult life such as increased anxiety-like behavior and hyperactivity of hypothalamo-pituitary-adrenal (HPA) axis system. The present study was designed to investigate whether prenatal stress could induce spatial learning impairment in aged female rats. Furthermore, since it has been recently reported that insulin-like growth factor 1 (IGF-1) attenuates spatial learning deficits in aged rats and promotes neurogenesis in the hippocampus, we assessed the impact of a chronic infusion of IGF-1 on age-related disorders. Our results show that females stressed during prenatal life exhibit learning impairments in the water maze task. Chronic IGF-1 treatment restores their spatial abilities, reduces their HPA axis dysfunction and increases plasma estradiol levels. Parallel to these effects, chronic IGF-1 up-regulates neural proliferation in the dentate gyrus of the hippocampus. These findings support the hypothesis of an early programming of the vulnerability to some neurological diseases during senescence and reinforce the potential therapeutic interest of IGF-1 during brain aging.     

Primate-specific alterations in neural stem/progenitor cells in the aged hippocampus

In the dentate gyrus of the hippocampus, new neurons are generated from neural stem/progenitor cells (NPCs) throughout life. As aging progresses, the rate of neurogenesis decreases exponentially, which might be responsible, in part, for age-dependent cognitive decline in animals and humans. However, few studies have analyzed the alterations in NPCs during aging, especially in primates. Here, we labeled NPCs by triple immunostaining for FABP7, Sox2, and GFAP and found that their numbers decreased in aged macaque monkeys (>20 years old), but not in aged mice. Importantly, we observed marked morphological alterations of the NPCs in only the aged monkeys. In the aged monkey hippocampus, the processes of the NPCs were short and ran horizontally rather than vertically. Despite these alterations, the proliferation rate of the NPCs in aged monkeys was similar to that in young monkeys. Thus, morphological alterations do not affect the proliferation rate of NPCs, but may be involved in the maintenance of NPCs in aged primates, including elderly humans.     

孕鼠铝暴露对仔鼠齿状回神经干细胞的影响

目的:探讨孕鼠铝暴露对其仔鼠海马齿状回神经干细胞的影响.方法:雌性SD大鼠在围产期经灌胃染铝(对照组以蒸馏水、染铝组以AlCl3 100mg·kg-1·d-1灌胃),分别取胚胎18d、1月、3月龄仔代鼠脑组织,常规石蜡包埋,冠状连续切片,对海马齿状回经巢蛋白免疫组织化学显色,对阳性反应细胞进行计数,测量阳性反应产物的平均光密度.结果:染铝组子代巢蛋白免疫组织化学显色阳性细胞数均明显少于对照组,阳性反应产物平均光密度值低于对照组.结论:大鼠孕期染铝可抑制子代鼠齿状回颗粒层神经干细胞增殖,铝可能抑制海马神经发生.     

复方丹参对脑缺血再灌注后大鼠海马和齿状回神经细胞凋亡及Bcl-2 mRNA表达的影响

目的:探讨中药复方丹参对大鼠脑缺血再灌注后海马和齿状回神经细胞凋亡及Bcl-2 mRNA表达的影响。方法:采用大脑中动脉内栓线法建立大鼠大脑中动脉缺血再灌注模型,应用原位细胞凋亡检测和原位杂交技术检测大鼠海马和齿状回神经细胞凋亡和Bcl-2 mRNA的表达并做图像分析。结果:与假手术对照组比较,缺血再灌注组凋亡神经细胞主要位于缺血侧海马CA1、CA3区,齿状回凋亡细胞较少。3个区神经细胞Bcl-2mRNA的表达在缺血再灌注2 h后升高,随时间的延长逐渐增强。复方丹参组神经细胞Bcl-2 mRNA的表达明显强于缺血再灌组,而凋亡神经细胞数明显较低。结论:复方丹参可通过上调神经细胞Bcl-2 mRNA的表达,抑制神经细胞凋亡,从而减轻缺血再灌注对大鼠海马和齿状回的损伤。     

模拟失重后大鼠海马齿状回神经发生的实验研究

观察模拟失重对大鼠海马齿状回神经发生的影响,为进一步阐明模拟失重对成年大鼠海马齿状回神经发生影响的规律及其相关生物学机制提供基本的实验依据。采用尾部悬吊法建立大鼠模拟失重模型,通过5-溴-2’-脱氧尿苷(5-bromo-2’-de-oxyuridine,BrdU)标记分裂细胞、微管相关蛋白(doublecortin,DCX)标记神经干细胞、神经元核蛋白(NeuN)标记神经元及胶质原纤维酸性蛋白(GFAP)标记神经胶质细胞的单、双重免疫组织化学染色方法比较尾部悬吊后7、14、28d模拟失重组大鼠与相应时间对照组大鼠之间海马齿状回神经前体细胞增殖、迁移和分化的情况。结果显示:模拟失重后7、14d尾部悬吊法模拟失重大鼠齿状回的BrdU免疫阳性细胞数目较相应对照组明显减少(P<0.01),而模拟失重后28d时两组大鼠齿状回BrdU免疫阳性细胞数目无显著差异(P>0.05)。本研究结果提示,模拟失重可抑制海马齿状回神经发生的水平。     

切割穹窿海马伞大鼠海马内Lhx8 mRNA表达的变化

目的:探讨切割穹窿海马伞大鼠切割侧与正常侧海马内Lhx8 mRNA表达的差异。方法:切割SD大鼠右侧穹窿海马伞。切割后7d制备海马冰冻切片,用体外转录法制备地高辛标记的Lhx8 RNA探针进行原位杂交,分析切割侧和正常侧海马锥体细胞层和齿状回颗粒层中及齿状回门区和颗粒下层中的Lhx8 mRNA阳性细胞的数量和平均光密度值。结果:切割侧和正常侧海马锥体细胞层和齿状回颗粒层Lhx8 mRNA阳性细胞数量无明显差异,但切割侧平均光密度值较正常侧明显增加;在齿状回的门区和颗粒下层,切割侧Lhx8 mRNA阳性细胞数和平均光密度值均较正常侧升高。结论:切割穹窿海马伞后海马中Lhx8 mRNA表达上调,可能与其中的神经干细胞向胆碱能神经元分化的神经再生机制有关。     

颅脑损伤后内源性神经干细胞增殖与迁移中的基质细胞衍生因子1*☆

背景：神经干细胞的迁移在颅脑损伤中起着极其重要的作用,但是其具体迁移机制尚不明确。 目的：观察大鼠颅脑损伤后基质细胞衍生因子1在内源性神经干细胞的增殖与迁移中的作用。 方法：采用Feeney’s等的方法用自制自由落体撞击器撞击大鼠左侧皮质运动感觉区以制备大鼠中度重型颅脑损伤模型,于伤后6 h,3 d,5 d,7 d灌注取脑,通过冰冻切片免疫组织化学检测Nestin及基质细胞衍生因子1表达,比较分析大鼠颅脑损伤后基质细胞衍生因子1和内源性神经干细胞的增殖与迁移之间的关系。并设正常对照组和假手术组做对照。 结果与结论：颅脑损伤大鼠的神经行为学评分与对照组比较差异显著。冰冻切片免疫组织化学显示：伤后3 d,基质细胞衍生因子1表达较对照组明显,海马区可见大量Nestin阳性细胞,未见向损伤区迁移;伤后5 d和7 d,基质细胞衍生因子1表达更明显,范围扩大,损伤区可见少量Nestin阳性细胞。对照组及假手术组未有上述改变。结果表明大鼠颅脑损伤后基质细胞衍生因子1表达时间推移越加明显,提示基质细胞衍生因子1参与内源性神经干细胞的增殖及向损伤区迁移的过程。 关键词：基质细胞衍生因子1;颅脑损伤;内源性神经干细胞;细胞迁移;Nestin doi:10.3969/j.issn.1673-8225.2012.06.011     

Effects of aging on the electrophysiological properties of layer 5 pyramidal cells in the monkey prefrontal cortex

A significant decline in executive system function mediated by the prefrontal cortex (PFC) often occurs with normal aging. In vitro slice studies have shown that layer 2/3 pyramidal cells in the monkey PFC exhibit increased action potential (AP) firing rates which may, in part, contribute to this decline. Given that layer 5 cells also play a role in executive system function, it is important to determine if similar age-related changes occur in these cells. Whole-cell patch-clamp recordings in in vitro slices prepared from the PFC of young and aged behaviorally characterized rhesus monkeys were employed to answer this question. Basic membrane and repetitive AP firing properties were unaltered with age. Aged cells exhibited significantly decreased single AP amplitude, duration and fall time and increased slow afterhyperpolarization (sAHP) amplitude, but these changes were not associated with cognitive performance. This study demonstrates that layer 5 pyramidal cells, unlike layer 2/3 pyramidal cells, undergo only modest electrophysiological changes with aging, and that these changes are unlikely to contribute to age-related cognitive decline.     

1型糖尿病脑病大鼠空间学习记忆与海马齿状回神经干细胞增殖的观察

目的揭示1型糖尿病继发性脑病变(糖尿病脑病)的发生与海马齿状回颗粒下区(SGZ)神经干细胞增殖之间的关系。方法应用链脲佐菌素(溶解于柠檬酸缓冲液中)腹腔注射,将成年雄性Wistar大鼠建立成1型糖尿病脑病模型;将用柠檬酸缓冲液腹腔注射的大鼠或正常大鼠分别作为载体模型组或正常对照组。在建立模型成功后的60d,用Morris水迷宫和5-溴脱氧尿嘧啶(BrdU,一种神经干细胞合成DNA的标记物)免疫组化方法,观察各组大鼠空间学习记忆能力以及SGZ神经干细胞(BrdU阳性细胞)的变化。结果1型糖尿病脑病模型大鼠的逃避潜伏期和游泳距离均较载体模型组或正常对照组大鼠明显延长(P<0.01);而且该脑病组大鼠SGZ的BrdU阳性细胞数也明显低于载体模型组或正常对照组大鼠(P<0.01)。结论个体内长期缺乏胰岛素可导致SGZ神经干细胞增殖出现障碍,从而引发空间学习记忆能力下降,这可能是诱发1型糖尿病脑病的一个因素。