氯化钴和跑台运动对大鼠海马神经发生及低氧诱导因子-1水平的影响

目的:比较氯化钴(CoCl2)所致机体低氧和跑台运动对大鼠海马齿状回新生细胞数量和低氧诱导因子-1(HIF-1)水平的影响.方法:腹腔注射CoCl2和BrdU于动物,运动方式为跑台运动,大鼠海马齿状回新生细胞和HIF-1采用免疫荧光显色显示.结果:小强度跑台运动组大鼠海马齿状回内BrdU免疫阳性(BrdU+)细胞数量显...     

大鼠精神分裂症后自发性运动量及海马神经发生的改变

目的:探讨成年大鼠精神分裂症后自发性运动量和海马神经发生的改变。方法:通过连续2周腹腔注射环苯已哌啶(phencyclidine,PCP)建立大鼠精神分裂症模型,利用动物运动分析系统监测大鼠自发性运动量,5-溴-2-脱氧尿苷嘧啶(BrdU)标记新生的神经细胞,用免疫荧光标记法监测海马齿状回BrdU、NeuN、S-100β的表达,利用激光共聚焦显微镜观察海马神经细胞的增殖与分化情况。结果:精神分裂症模型大鼠比对照组大鼠自发性运动量高出2～3倍(P0.05);BrdU阳性细胞数约下降了24%(P0.05);两组BrdU阳性细胞的分化无明显差异性(P0.05),大多分化为神经元。结论:精神分裂症可导致成年大鼠自发性运动量增加,并引起海马神经发生的改变,降低神经细胞的增殖。     

氯化锂对成年小鼠海马神经发生的影响

目的：观察氯化锂(LiCl)对成年小鼠海马细胞增殖与神经发生的影响。方法：用5-溴-2-脱氧尿核苷(BrdU)标记新生细胞,免疫组化染色后统计新生细胞数量;应用BrdU与抗微管蛋白单克隆抗体(JuJI)／抗胶质纤维酸性蛋白多克隆抗体(GFAP)双标记,鉴别出BrdU阳性细胞的细胞类型。结果：LiCl组小鼠海马齿状回细胞增殖与神经发生明显强于对照组;新增殖的细胞约有70％为神经元,5％左右为神经胶质细胞。结论：LiCl增强了成年小鼠海马齿状回的细胞增殖与神经发生,这一功能对于中枢神经系统退行性疾病的预防与治疗可能有重要的意义。     

雌二醇对大鼠海马神经干细胞增殖的影响

目的观察雌二醇对大鼠海马神经干细胞增殖的影响及其作用机制。方法取20只孕17d的SD大鼠海马组织,进行神经干细胞的培养和增殖,添加不同浓度的雌二醇(E2)。通过5-溴脱氧尿嘧啶核苷(BrdU)免疫荧光、MTT方法检测神经干细胞的增殖;通过免疫荧光技术和巢蛋白(Nestin)双标观察神经干细胞球中雌激素受体ERα和ERβ的表达情况。结果 BrdU与MTT检测结果显示,随着雌二醇浓度从10-10mol/L增加至10-8mol/L,神经干细胞数量逐渐增加。雌二醇在10-8mol/L时,细胞增殖数目最多而且细胞活力最好。随着雌二醇浓度进一步增加至10-6mol/L,神经干细胞增殖能力逐渐下降。免疫荧光技术检测显示神经干细胞均表达ERα和ERβ两种受体。结论在一定浓度范围内,雌二醇能促进海马神经干细胞的增殖,并可能是通过ERα和ERβ介导促进神经干细胞增殖。     

慢性复合应激对成年大鼠海马NeuroD表达的影响

本实验通过观察慢性复合应激对成年大鼠海马NeuroD表达的影响,探讨慢性复合应激与海马神经发生的关系。将成年雄性大鼠32只随机分为慢性复合应激组(简称应激组)和正常对照组(简称对照组)。应激组动物每天不规律交替暴露于四种复合应激原中,共持续6周。然后运用免疫组织化学染色、Western-blot和RT-PCR技术分别观察海马内NeuroD阳性神经元数量、NeuroD蛋白水平和核酸水平的变化。结果显示:慢性复合应激组动物海马齿状回NeuroD阳性神经元数量明显增多(P<0.05);海马NeuroD蛋白的表达明显增强(P<0.05);海马NeuroD mRNA水平明显上调(P<0.05)。表明慢性复合应激可引起海马NeuroD阳性神经元数量增多和NeuroD表达水平升高,提示慢性复合应激可能促进大鼠海马的神经发生。     

海马神经发生障碍与阿尔兹海默病发病机制

<正>早在1907年,德国神经病理学家Alois Alzheimer首次将阿尔兹海默病(Alzheimer’s disease,AD)定义为Dementia Praecox,并将其描述为一种以进行性记忆能力受损和认知功能障碍为特征的神经退行性疾病。患者主要表现为渐进性记忆障碍、认知功能障碍、人格改变及语言障碍等神经精神症状[1],严重影响社交、职业与生活功能。AD的主要病理改变包括神经元内逐渐出现的神经纤维缠结导致细胞骨架蛋白Tau蛋白的过度磷酸化,胞外沉积的淀粉样前体蛋白β(β-Amyloid,Aβ)寡聚化,老年斑形成以及大面积的神经元死[2]     

缺氧对新生大鼠海马神经干细胞增殖和分化的影响

目的探讨单纯性缺氧对新生大鼠海马神经干细胞(NSCs)增殖和分化的影响。方法将36只新生1d大鼠随机均分为N组(正常对照组)、Q2组(缺氧2h组)、Q5组(缺氧5h组)。将海马组织在无血清培养液(均含有碱性成纤维生长因子bFGF、表皮生长因子EGF和白细胞抗原B27)中,分别进行原代培养、单克隆培养和传代培养,单克隆培养细胞进行巢蛋白(Nestin)和Hoechst33342免疫荧光双标染色;传代培养的细胞传三代诱导分化,诱导分化3d的细胞分别行神经元特异性烯醇化酶(NSE)、胶质纤维酸性蛋白(GFAP)和Hoechst3342免疫荧光双标染色,计数NSE阳性细胞比例,进行统计学分析。结果单克隆培养的细胞均呈Nestin阳性表达,诱导分化的细胞部分呈NSE或GFAP阳性表达。Q2组、N组、Q5组细胞原代培养克隆球直径达2μm的时间分别为7d、10d、13d。传3代后,对各组细胞进行诱导分化,Q2组细胞诱导分化为神经元的比例明显高于N组,Q5组的细胞诱导分化为神经元的比例明显低于N组。结论短时间缺氧可促进在体海马神经干细胞增殖和诱导其向神经元分化,长时间缺氧则抑制在体神经干细胞增殖和向神经元分化。     

环孢素A对新生小鼠的海马神经发生和认知能力的影响

目的检测免疫抑制剂环孢素A对小鼠行为和神经发生的影响,为进一步研究免疫对小鼠中枢神经系统神经发生的分子机制研究做理论依据。方法实验随机分为环孢素A组和对照组。新生C57BL/6小鼠于出生24 h内背部皮下接种环孢素A,对照组皮下注射等量的生理盐水。14 d时用免疫荧光的方法检测海马Brd U+、DCX+/Brd U+、Neu N+/Brd U+细胞数量的变化,28 d时用矿场和水迷宫的方法检测其行为学的变化。结果与其对照组相比,环孢素A组小鼠的探索,自发性活动和学习记忆能力明显降低;Brd U+、DCXA/Brd U+、Neu N+/Brd U+细胞数量的明显下降表明海马神经发生受抑制。结论新生期给予环孢素A可以抑制新生小鼠的认知能力和海马神经发生。     

短暂性脑缺血对C57BL/6小鼠海马区神经发生的影响

目的:利用小鼠急性全脑缺血模型观察急性脑缺血对海马神经发生的影响。方法:将C57BL/6雄性小鼠(6~8周)随机分为脑缺血组和假手术组。采用双侧颈动脉结扎法建立短暂性全脑缺血模型;利用HE染色观察脑缺血后不同时间(1周,2周)海马区形态学变化;采用免疫组织荧光染色观察缺血后海马区caspase-3表达变化;利用Ed U染色观察缺血3 d、7 d、14 d和28 d后,海马区神经干细胞增殖变化;利用免疫组织荧光染色观察缺血3 d、7 d、14 d和28 d后,海马区nestin、胶质纤维酸性蛋白(GFAP)及少突胶质细胞特异蛋白(OSP)等蛋白表达变化,判断脑缺血对海马区神经干细胞分化的影响。结果:脑缺血7 d后,小鼠海马CA1区神经元数目减少,caspase-3阳性细胞增加(P0.05)。海马DG区Ed U阳性细胞数量在第3 d开始增加(P0.05),第1周达到峰值(P0.05);海马CA1区Ed U阳性细胞数量在缺血后1周开始增加(P0.05),缺血2周后逐渐降低。海马DG区nestin、GFAP及OSP阳性细胞数量均在缺血3 d后开始增加(P0.05),缺血1周后达到峰值(P0.05),2周后逐渐降低。海马CA1区GFAP及OSP阳性细胞数量在缺血3 d后开始增加(P0.05),缺血1周后达到峰值(P0.05),2周后逐渐降低。结论:脑缺血激活了海马DG区神经干细胞,使干细胞增殖,并向神经元、星形胶质细胞、少突胶质细胞分化,同时逐渐向CA1区迁移。     

大鼠穹隆海马伞切割对海马伞内神经干细胞再生的影响

目的 检测损伤的穹隆海马伞内自体神经干细胞的再生情况.方法 SD大鼠7只,切割左侧穹隆海马伞,术后腹腔注射5-溴脱氧尿嘧啶核苷(BrdU).术后7d取脑组织制备冷冻切片,行Nestin、BrdU免疫荧光检测;取穹隆海马伞组织进行神经干细胞的体外分离培养,对获得的细胞球进行增殖性、胚胎性以及多分化潜能的检测.结果 切割...     

Effects of neonatal flutamide treatment on hippocampal neurogenesis and synaptogenesis correlate with depression-like behaviors in preadolescent male rats

The prevalence of major depressive disorder (MDD) in adult men is roughly half that of women. Clinical evidence supports a protective effect of androgens against depressive disorders in men. The developing brain is subject to androgen exposure but a potential role for this in depression during adulthood has not been considered. In order to explore this question we treated newborn male rat pups with the androgen receptor antagonist flutamide to block endogenous androgen action and then conducted behavioral tests prior to puberty. Depression-like behaviors were assessed with the Forced Swim Test (FST) and the Sucrose Preference Test (SPT), and anxiety-like behaviors were assessed with the Open Field Test (OFT) and the Novelty-Suppressed Feeding Test (NSFT). Compared to the vehicle-treated controls, neonatal-flutamide treatment caused a significant increase in depression-like behaviors in preadolescent male rats but did not cause any significant difference in anxiety-like behaviors. In separate experiments, male pups with and without flutamide treatment were injected with 5-bromo-2′-deoxyuridine-5′-monophosphate (BrdU) from postnatal day (PND) 1 to 4 to label newly produced cells or the hippocampi were Golgi-Cox imbedded and pyramidal neurons visualized. Three lines of evidence indicate neonatal flutamide treatment inhibits hippocampal neurogenesis and neuronal dendritic spine formation in preadolescent male rats. Compared to vehicle controls, flutamide treatment significantly decreased (1) the number of microtubal associated protein-2+ (MAP-2) neurons in the CA1 region, (2) the number of MAP-2+ neurons in the dentate gyrus (DG) region of the hippocampus, and (3) the density of dendritic spines of pyramidal neurons in the CA1 region. However, there was no effect of flutamide treatment on the number of glial fibrillary acidic protein (GFAP)+ or GFAP+/BrdU+ cells in the hippocampus. This study suggests that the organizational effect of androgen-induced hippocampal neurogenesis is antidepressant.     

慢性应激抑郁状态对大鼠海马神经元再生的影响

目的:探讨慢性应激性刺激引起的抑郁状态对大鼠海马神经元再生的影响。方法:建立大鼠慢性应激性抑郁症模型,通过开场实验和蔗糖饮水实验观察大鼠行为学变化;取大鼠脑冰冻切片行Doublecortin(DCX)免疫荧光检测海马新生神经元。结果:慢性应激抑郁模型大鼠开场实验水平运动得分和垂直运动得分降低,蔗糖偏嗜度降低,且体重明显减轻;免疫荧光结果显示慢性应激抑郁模型大鼠海马齿状回颗粒下层(subgranularzone SGZ)DCX阳性细胞减少。结论:慢性应激性刺激引起的抑郁状态下大鼠海马神经元再生能力减弱,提示海马神经元再生的损害可能参与了抑郁症的病理过程。     

Microenvironmental elements supporting adult hippocampal neurogenesis

Neurogenesis continues into adulthood in two distinct regions, the subventricular zone of the forebrain and the subgranular zone of the dentate gyrus. Transplantation experiments have suggested that the two neurogenic regions have a special microenvironment to support the proliferation and differentiation of stem or progenitor cells. As the candidates of the microenvironment, three elements have so far been proposed: (i) astrocytes; (ii) polysialyl neural cell adhesion molecule (PSA-NCAM)-expressing immature neurons; and (iii) blood vessels. In the early developmental process of neurogenesis, newly born cells make clusters within the neurogenic regions and the clusters are found to interact structurally with astrocytes, polysialic acidexpressing immature cells, endothelium and extravascular basal laminae of blood vessels. Furthermore, recent reports have shown that astrocytes support the proliferation and differentiation of stem cells in vitro. These results suggest that these microenvironmental elements contribute to the cell proliferation and differentiation of stem or progenitor cells. However, it remains to be determined how the microenvironmental elements support adult neurogenesis functionally and coordinate with each other.     

Rapid eye movement sleep deprivation contributes to reduction of neurogenesis in the hippocampal dentate gyrus of the adult rat

Study Objectives:

The dentate gyrus (DG) of the adult hippocampus contains progenitor cells, which have potential to differentiate into neurons. Previously we reported that 96 hours of total sleep deprivation reduces neurogenesis in the DG of adult rats. Loss of either non-rapid eye movement (NREM) or rapid eye movement (REM) sleep could have contributed to the effect of total sleep deprivation. The present study assessed the effect of 4 days of REM sleep deprivation (REMD) on neurogenesis.

Design:

REMD was achieved by brief treadmill movement initiated by automatic online detection of REM sleep. A yoked-control (YC) rat was placed in the same treadmill and experienced the identical movement regardless the stage of the sleep-wake cycle. The thymidine analog 5- bromo- 2′- deoxy-uridine and the intrinsic proliferation marker, Ki-67, were both used to label proliferating cells.

Setting:

Basic neurophysiology laboratory.

Participants:

Male Sprague-Dawley male rats (300 – 320 g)

Results:

REM sleep was reduced by 85% in REMD rats and by 43% in YC, compared with cage control animals and by 79% in REMD rats compared with YC. NREM sleep and slow wave activity within NREM did not differ in REMD and YC groups. Cell proliferation was reduced by 63 % in REMD compared with YC rats, and by 82% and 51%, respectively, in REMD and YC rats compared with cage controls. Across all animals, cell proliferation exhibited a positive correlation with the percentage of REM sleep (r = 0.84, P < 0.001). Reduced cell proliferation in REMD rats was confirmed with the intrinsic proliferation marker, Ki-67. REMD also reduced the percentage of proliferating cells that later expressed a mature neuronal marker.

Conclusions:

The present findings support a hypothesis that REM sleep-associated processes facilitate proliferation of granule cells in the adult hippocampal DG.

Citation:

Guzman-Marin R; Suntsova N; Bashir T; Nienhuis R; Szymusiak R; McGinty D. Rapid eye movement sleep deprivation contributes to reduction of neurogenesis in the hippocampal dentate gyrus of the adult rat. SLEEP 2008;31(2):167–175.     

Reproductive experience alters hippocampal neurogenesis during the postpartum period in the dam

Pregnancy and the postpartum period are a time of maximal neural and behavioral plasticity. Recent work has shown that hippocampus-dependent learning and memory performance and hippocampus morphology are affected by motherhood and reproductive experience (number of times pregnant and given birth). Adult neurogenesis in the dentate gyrus of the hippocampus is influenced by steroid hormones such as estradiol and corticosterone, which fluctuate during pregnancy and the postpartum period. Thus, it is possible that hippocampal neurogenesis may be affected by motherhood and reproductive experience. The present study aimed to investigate the role of reproductive experience on hippocampal neurogenesis via cell proliferation and cell survival and to determine whether differences were due to the effect of pregnancy and/or pup-exposure alone. Four groups of female Sprague-Dawley rats were used; multiparous, primiparous, nulliparous, and nulliparous rats exposed to pups. All rats were injected with 5-bromo-2-deoxyuridine (BrdU) (200 mg/kg) approximately 24 h after birth/pup-exposure with age-matched controls. Rats were perfused either 24 h (Expt. 1: Cell proliferation) or 21 days (Expt. 2: Cell survival) after BrdU injection. Results show there is a significant decrease in cell proliferation in the dentate gyrus of primiparous and multiparous rats during the early postpartum period, and a decrease in cell survival in the dentate gyrus during the postpartum in primiparous rats, regardless of pup-exposure, compared with all other groups. In addition, brief pup exposure to nulliparous rats significantly increased cell proliferation and cell death in the dentate gyrus, while 22 days of pup exposure to nulliparous rats (sensitized rats) resulted in increased cell survival and cell death in the dentate gyrus. Collectively these results indicate that reproductive experience significantly affects hippocampal neurogenesis and that these effects are not due to the effect of pregnancy or pup-exposure alone.     

Intact neurogenesis is required for benefits of exercise on spatial memory but not motor performance or contextual fear conditioning in C57BL/6J mice

The mammalian hippocampus continues to generate new neurons throughout life. Experiences such as exercise, anti-depressants, and stress regulate levels of neurogenesis. Exercise increases adult hippocampal neurogenesis and enhances behavioral performance on rotarod, contextual fear and water maze in rodents. To directly test whether intact neurogenesis is required for gains in behavioral performance from exercise in C57BL/6J mice, neurogenesis was reduced using focal gamma irradiation (3 sessions of 5 Gy). Two months after treatment, mice (total n=42 males and 42 females) (Irradiated or Sham), were placed with or without running wheels (Runner or Sedentary) for 54 days. The first 10 days mice received daily injections of bromodeoxyuridine (BrdU) to label dividing cells. The last 14 days mice were tested on water maze (two trials per day for 5 days, then 1 h later probe test), rotarod (four trials per day for 3 days), and contextual fear conditioning (2 days), then measured for neurogenesis using immunohistochemical detection of BrdU and neuronal nuclear protein (NeuN) mature neuronal marker. Consistent with previous studies, in Sham animals, running increased neurogenesis fourfold and gains in performance were observed for the water maze (spatial learning and memory), rotarod (motor performance), and contextual fear (conditioning). These positive results provided the reference to determine whether gains in performance were blocked by irradiation. Irradiation reduced neurogenesis by 50% in both groups, Runner and Sedentary. Irradiation did not affect running or baseline performance on any task. Minimal changes in microglia associated with inflammation (using immunohistochemical detection of cd68) were detected at the time of behavioral testing. Irradiation did not reduce gains in performance on rotarod or contextual fear, however it eliminated gain in performance on the water maze. Results support the hypothesis that intact exercise-induced hippocampal neurogenesis is required for improved spatial memory, but not motor performance or contextual fear in C57BL/6J mice.     

Exercise-induced changes in dendritic structure and complexity in the adult hippocampal dentate gyrus

Neurogenesis is a constitutive activity in the adult dentate gyrus whereby new cells are created in the subgranular zone, before becoming neurons in the dentate gyrus granule cell layer. New granule cells are thought to migrate from the subgranular zone outwards to the edge of the cell layer as they mature. In these experiments we examined the dendritic morphology of granule cells in the subgranular zone, and the inner and outer regions of the granule cell zone in Sprague-Dawley rats with low and high rates of neurogenesis. In animals with lower rates of neurogenesis, the number of primary dendrites, degree of dendritic complexity and total dendritic length was lowest in cells located in the subgranular zone, higher in inner granule cell zone neurons, and highest in outer granule cell zone granule cells. Subgranular zone granule cells typically extended one primary dendrite and had a simple, immature dendritic tree, while granule cells in the outer granule cell zone had an increased number of primary dendrites, greater dendritic complexity, and greater total dendritic length. Animals that engaged in voluntary exercise showed increased neurogenesis, and the proportion of cells with one or two primary dendrites was increased in all of the granule cell zones. Despite having fewer primary processes, these cells showed enhanced dendritic complexity and an overall increase in their total dendritic length. These results indicate that granule cell dendritic morphology may be indicative of the age and position of a cell in the granule cell layer, but that in animals with increased rates of neurogenesis, the proportion of cells exhibiting what is considered an immature phenotype is increased throughout the all regions of the dentate gyrus cell layer.     

Adult neurogenesis is reduced in the dorsal hippocampus of rats displaying learned helplessness behavior

Clinical and preclinical studies suggest that the hippocampus has a role in the pathophysiology of major depression. In the learned helplessness (LH) animal model of depression after inescapable shocks (ISs) animals that display LH behavior have reduced cell proliferation in the hippocampus; this effect can be reversed by antidepressant treatment. Using this model, we compared rats that displayed LH behavior and rats that did not show LH behavior (NoLH) after ISs to determine whether reduced hippocampal cell proliferation is associated with the manifestation of LH behavior or is a general response to stress. Specifically, we examined cell proliferation, neurogenesis, and synaptic function in dorsal and ventral hippocampus of LH and NoLH animals and control rats that were not shocked. The LH rats had showed reduced cell proliferation, neurogenesis, and synaptic transmission in the dorsal hippocampus, whereas no changes were seen in the ventral hippocampus. These changes were not observed in the NoLH animals. In a group of NoLH rats that received the same amount of electrical shock as the LH rats to control for the unequal shocks received in these two groups, we observed changes in Ki-67⁺ cells associated with acute stress. We conclude that reduced hippocampal cell proliferation and neurogenesis are associated with the manifestation of LH behavior and that the dorsal hippocampus is the most affected area.