卡马西平对成年癫癎大鼠海马齿状回BrdU/NeuN表达水平及其对空间记忆的影响

目的 研究卡马西平对成年癫癎大鼠海马齿状回新生神经元的影响及其与空间记忆之间的关系.方法 采用氯化锂和匹罗卡品联合诱导大鼠癫痫 间模型,利用5-溴脱氧尿苷嘧啶与神经元核性蛋白双标记观察海马齿状回内源性神经前体细胞分化为成熟神经元的情况;利用行为学分析评价大鼠的空间记忆.结果 (1)卡马西平可增加癫癎大鼠海马齿状回新生成熟神经元的数量(P＜0.05);(2)卡马西平对癫癎大鼠的空间记忆有明显改善作用(P＜0.01).结论 卡马西平增加癫癎大鼠海马齿状回新生成熟神经元形成,是其改善癫癎大鼠空间记忆的可能机制之一.     

卡马西平对成年癫大鼠海马齿状回BrdU/NeuN表达水平及其对空间记忆的影响

目的研究卡马西平对成年癫大鼠海马齿状回新生神经元的影响及其与空间记忆之间的关系。方法采用氯化锂和匹罗卡品联合诱导大鼠癫模型,利用5-溴脱氧尿苷嘧啶与神经元核性蛋白双标记观察海马齿状回内源性神经前体细胞分化为成熟神经元的情况;利用行为学分析评价大鼠的空间记忆。结果 (1)卡马西平可增加癫大鼠海马齿状回新生成熟神经元的数量(P<0.05);(2)卡马西平对癫大鼠的空间记忆有明显改善作用(P<0.01)。结论卡马西平增加癫大鼠海马齿状回新生成熟神经元形成,是其改善癫大鼠空间记忆的可能机制之一。     

卡马西平对匹罗卡品诱导成年癫间疒大鼠海马齿状回神经前体细胞增殖的影响

目的研究卡马西平对成年癫大鼠海马齿状回内源性神经前体细胞增殖的影响。方法采用氯化锂和匹罗卡品联合诱导大鼠癫模型,将癫大鼠随机分为癫对照组和癫卡马西平组,正常大鼠随机分为正常对照组和正常卡马西平组。癫对照组和正常对照组给以蒸馏水灌胃,同时癫卡马西平组和正常卡马西平组给予卡马西平灌胃。于灌胃后第6d腹腔注射5-溴脱氧尿苷嘧啶(BrdU)标记海马齿状回的内源性神经前体细胞的增殖情况;用免疫组化方法观察各组大鼠在注射BrdU后第1d、第7d齿状回BrdU阳性细胞数量的表达。结果①注射BrdU后第1d,癫对照组大鼠海马齿状回BrdU阳性细胞数较正常对照组明显增加(P<0.01),癫卡马西平组大鼠海马齿状回BrdU阳性细胞数较癫对照组减少(P<0.05);②注射BrdU后第7d,癫对照组大鼠海马齿状回BrdU阳性细胞数较正常对照组明显增加(P<0.01),癫卡马西平组大鼠海马齿状回BrdU阳性细胞数较癫对照组明显减少(P<0.05)。结论卡马西平抑制癫大鼠海马齿状回内源性神经前体细胞增殖。     

托吡酯对癫痫大鼠海马细胞外液氨基酸和神经元凋亡的影响

目的研究托吡酯对癫癎大鼠海马区细胞外液氨基酸和神经元凋亡的影响.方法采用戊四氮(PTZ)致癎模型,大鼠癫癎发作后连续给予托吡酯(TPM)80 mg·kg-1·d-1和卡马西平40 mg·kg-1·d-1,共14 d.以TUNEL方法标记DNA片段,原位检测海马凋亡的神经细胞.脑内微透析技术采集大鼠海马细胞外液,反相高效液相色谱技术测定氨基酸类神经递质的含量.结果TPM组、卡马西平组与对照组比较,凋亡细胞数存在显著差异(P＜0.001),TPM组与卡马西平组相比无显著差异(P＞0.05).TPM可明显升高海马细胞外液γ-氨基丁酸(GABA)水平,并降低谷氨酸(Glu)浓度.结论TPM可减轻大鼠癫癎发作后的神经元损伤,这种作用可能是氨基酸变化的结果;但在我们的实验中,没有发现TPM对癫癎后脑损伤比卡马西平有更明显的神经保护作用.     

不同程度的性发作对成年大鼠空间学习记忆影响的研究

目的研究不同程度的性发作对成年大鼠空间学习记忆的影响。方法采用氯化锂和匹罗卡品联合诱导大鼠不同程度的癫模型(轻型和重型)。于造模后第6d给所有大鼠腹腔注射5-溴脱氧尿苷嘧啶(BrdU+)标记海马齿状回增殖的内源性神经前体细胞;用免疫组化方法观察各组大鼠注射BrdU+后第1d和第28d齿状回BrdU+阳性细胞数以及第28d的BrdU+/神经元核性蛋白(NeuN+)阳性细胞数及分布情况;利用Morris水迷宫评价大鼠的学习记忆功能。结果与正常组及轻型组比较,在各个时间点重型组海马齿状回BrdU+细胞数均增加(P<0.05),28d时BrdU+/NeuN+细胞数相应增多,但其占BrdU+细胞数的比例明显下降(P<0.05)。28d时重型组大鼠的学习记忆功能较正常组及轻型组明显下降(P<0.05)。结论严重的癫发作造成大鼠对空间学习记忆功能的损害,可能与其刺激大鼠海马齿状回内源性神经前体细胞增殖水平,抑制其分化为新生的成熟神经元有关。     

老年大鼠脑出血后海马齿状回神经干细胞的增殖与分化

目的 观察老年大鼠脑出血后海马齿状回神经干细胞(NSCs)的增殖与分化,探讨脑出血后NSCs的变化规律.方法 制作老年大鼠脑出血模型,5-溴脱氧尿核苷(BrdU)腹腔注射标记增殖细胞,用免疫组化法检测大鼠海马齿状回BrdU、神经元核抗原(NeuN)、胶质纤维酸性蛋白(GFAP)阳性细胞数的变化.结果 正常组和假手术组老年大鼠海马齿状回均有少量BrdU阳性细胞,脑出血后大鼠各时间段的BrdU阳性细胞数目均较正常组和假手术组明显增加,7d组达到峰值后逐渐下降,28d组仍高于正常组和假手术组.正常老年大鼠海马齿状回可见少量BrdU/NeuN和BrdU/GFAP双标阳性细胞,脑出血后双标阳性细胞数较正常组明显增加.结论 脑出血后老年大鼠海马齿状回NSCs增殖明显,且可以向神经元和神经胶质细胞分化.     

丰富环境促进颞叶癫(痫)大鼠神经发生及其机制的研究

目的 探讨丰富环境对颞叶癫(痫)大鼠齿状回新生细胞分化和存活的影响及其相关分子机制.方法 成年Wistar 大鼠随机分为4组:假手术组、丰富环境+假手术组、癫(痫)组、丰富环境+癫(痫)组,各组均n=15.大鼠侧脑室注射海人酸制作颞叶癫(痫)模型.丰富环境干预30 d后,应用免疫荧光技术观察大鼠海马齿状回的新生细胞分化和存活情况,用Western blot方法检测各组海马脑源性神经营养因子(BDNF)、cAMP应答元件结合蛋白(pCREB)、蛋白激酶A(PKA)表达水平.结果 丰富环境+假手术组、丰富环境+癫(痫)组齿状回新生细胞标记物(BrdU)和新生成熟神经细胞标记物(BrdU/NeuN)阳性细胞数分别多于假手术组、癫(痫)组(P＜0.05),而新生星形胶质细胞BrdU/GFAP阳性细胞数无统计学意义,并且丰富环境+假手术组、丰富环境+癫(痫)组海马BDNF和pCREB蛋白表达水平分别高于假手术组、癫(痫)组(P＜o.05),而PKA蛋白表达水平无增高.结论 丰富环境可能通过增强pCREB/BDNF通路促进成年颞叶癫(痫)大鼠海马齿状回的神经发生.     

神经营养因子-3在颞叶癫(癎)后的表达与海马苔藓纤维发芽的关系

目的 探讨神经营养因子-3(NT-3)在颞叶癫(癎)大鼠海马内表达与苔藓纤维发芽(MFS)的可能关系.方法 大鼠侧脑室注射红藻氨酸(KA)建寺颞叶癫(癎)模型后,侧脑室注射NT-3反义寡核苷酸(ASODN)及正义寡核苷酸(SODN);应用免疫组化法观察海马NT-3表达;应用Timm银染方法,光镜和电镜观察海马MFS,并与空白对照组及脂质体对照组进行比较.结果 致(癎)后大鼠海马齿状回NT-3表达下降;海马苔藓纤维明显粗乱,侧支发芽;齿状回内分子层可见银标记突触末端,主要为轴-树型非对称突触,其中ASODN组海马NT-3蛋白水平降低及MFS程度更明显.结论 KA致痢和NT-3 ASODN均能降低大鼠海马齿状回NT-3表达,增加MFS程度.提示NT-3可能通过对MFS及突触重组作用来影响颞叶癫(癎)的发生和发展.     

新生期痫性发作对海马齿状回神经发生的影响

海马齿状回颗粒细胞层下区(subgranular zone,SGZ)是哺乳动物主要的神经发生区域之一。痫性发作可诱导SGZ新生神经细胞异常增殖、迁移、整合,而且可以对学习记忆能力产生影响。目前,新生期痫性发作后神经发生的机制尚未阐明,已有研究发现该过程受多种因素调节。本文就新生期痫性发作对海马齿状回神经发生的影响及可能的调节机制进行综述。     

匹罗卡品癫(癎)模型中蛋白质netrin-1的表达与苔藓纤维出芽的动态变化

目的:探讨神经诱向因子蛋白质netrin-1在癫(癎)持续状态后海马苔藓纤维出芽(MFS)中的作用.方法:氯化锂-匹罗卡品建立大鼠颞叶癫(癎)(TLE)模型,采用Timm染色和免疫组化的方法分别检测MFS和netrin-1在大鼠海马组织中的表达.结果:TLE组大鼠在模型形成的第2周和第4周,海马齿状回内netrin-1的表达较正常对照组明显增加,并可见到MFS,穿越齿状回颗粒细胞层到达内分子层,并形成一条致密的层状带.结论:癫(癎)状态后在海马齿状回netrin-1的表达上调,证明其可能参与了癫(癎)后MFS过程.     

Effects of CXCR7-neutralizing antibody on neurogenesis in the hippocampal dentate gyrus and cognitive function in the chronic phase of cerebral ischemia

Stromal cell-derived factor-1 and its receptor CXCR4 are essential regulators of the neurogenesis that occurs in the adult hippocampal dentate gyrus.However,the effects of CXCR7,a new atypical receptor of stromal cell-derived factor-1,on hippocampal neurogenesis after a stroke remain largely unknown.Our study is the first to investigate the effect of a CXCR7-neutralizing antibody on neurogenesis in the dentate gyrus and the associated recovery of cognitive function of rats in the chronic stage of cerebral ischemia.The rats were randomly divided into sham,sham+anti-CXCR7,ischemia and ischemia+anti-CXCR7 groups.Endothelin-1 was injected in the ipsilateral motor cortex and striatum to induce focal cerebral ischemia.Sham group rats were injected with saline instead of endothelin-1 via intracranial injection.Both sham and ischemic rats were treated with intraventricular infusions of CXCR7-neutralizing antibodies for 6 days 1 week after surgery.Immunofluorescence staining with doublecortin,a marker for neuronal precursors,was performed to assess the neurogenesis in the dentate gyrus.We found that anti-CXCR7 antibody infusion enhanced the proliferation and dendritic development of doublecortin-labeled cells in the dentate gyrus in both ischemic and sham-operated rats.Spatial learning and memory functions were assessed by Morris water maze tests 30-32 days after ischemia.CXCR7-neutralizing antibody treatment significantly reduced the escape latency of the spatial navigation trial and increased the time spent in the target quadrant of spatial probe trial in animals that received ischemic insult,but not in sham operated rats.These results suggest that CXCR7-neutralizing antibody enhances the neurogenesis in the dentate gyrus and improves the cognitive function after cerebral ischemia in rats.All animal experimental protocols and procedures were approved by the Institutional Animal Care and Use Committee of China Medical University(CMU16089 R)on December 8,2016.     

Emergence of spontaneous seizures during the year following lithium/pilocarpine-induced epilepsy and neuronal loss within the right temporal cortices

Thirty days after the induction of seizures in 16 rats with lithium (3 mEq/kg) and pilocarpine (30 mg/kg), the numbers of episodes of motor seizures (rapid forelimb clonus) during daily 10-minute observational periods were recorded for 11 months. The proportions of neuronal loss were ranked using two methods by light microscopy for all structures between the posterior and anterior commissures. Amounts of damage within the dentate gyrus, hilus (CA4), and CA3 field were most strongly correlated with numbers of seizures per month about 6 months before the brains were removed. The strongest correlations occurred between the amounts of damage within the right temporal cortices, even after the variance associated with damage within the dentate gyrus had been removed, and the numbers of seizures during the last 2 months. These results may explain the greater proportion of spontaneous seizures that begin with left side forelimb clonus and suggest a particular sensitivity of the right side of the brain to either their initiation or their consequences.     

Roles of astrocytes and microglia in seizure‐induced aberrant neurogenesis in the hippocampus of adult rats

Recent evidence showed that epileptic seizures increase hippocampal neurogenesis in the adult rat, but prolonged seizures result in the aberrant hippocampal neurogenesis that often leads to a recurrent excitatory circuitry and thus contributes to epileptogenesis. However, the mechanism underlying the aberrant neurogenesis after prolonged seizures remains largely unclear. In this study, we examined the role of activated astrocytes and microglia in the aberrant hippocampal neurogenesis induced by status epilepticus. Using a lithium‐pilocarpine model to mimic human temporal lobe epilepsy, we found that status epilepticus induced a prominent activation of astrocytes and microglia in the dentate gyrus 3, 7, 14, and 20 days after the initial seizures. Then, we injected fluorocitrate stereotaxicly into the dentate hilus to inhibit astrocytic metabolism and found that fluorocitrate failed to prevent the seizure‐induced formation of ectopic hilar basal dendrites but instead promoted the degeneration of dentate granule cells after seizures. In contrast, a selective inhibitor of microglia activation, minocycline, inhibited the aberrant migration of newborn neurons at 14 days after status epilepticus. Furthermore, with stereotaxic injection of lipopolysaccharide into the intact dentate hilus to activate local microglia, we found that lipopolysaccharide promoted the development of ectopic hilar basal dendrites in the hippocampus. These results indicate that the activated microglia in the epileptic hilus may guide the aberrant migration of newborn neurons and that minocycline could be a potential drug to impede seizure‐induced aberrant migration of newborn neurons. © 2009 Wiley‐Liss, Inc.     

Proepileptic influence of a focal vascular lesion affecting entorhinal cortex-CA3 connections after status epilepticus

In limbic seizures, neuronal excitation is conveyed from the entorhinal cortex directly to CA1 and subicular regions. This phenomenon is associated with a reduced ability of CA3 to respond to entorhinal cortex inputs. Here, we describe a lesion that destroys the perforant path in CA3 after status epilepticus (SE) induced by pilocarpine injection in 8-week-old rats. Using magnetic resonance imaging, immunohistochemical, and ultrastructural analyses, we determined that this lesion develops after 30 minutes of SE and is characterized by microhemorrhages and ischemia. After a longer period of SE, the lesion invariably involves the upper blade of the dentate gyrus. Adult rats treated with subcutaneous diazepam (20 mg kg for 3 days) did not develop the dentate gyrus lesion and had less frequent spontaneous recurrent seizures (p < 0.01). Young (3-week-old) rats rarely (20%) developed the CA3 lesion, and their spontaneous seizures were delayed (p < 0.01). To investigate the role of the damaged CA3 in seizure activity, we reinduced SE in adult and young epileptic rats. Using FosB/DeltaFosB markers, we found induction of FosB/DeltaFosB immunopositivity in CA3 neurons of young but not in adult rats. These experiments indicate that SE can produce a focal lesion in the perforant path that may affect the roles of the hippocampus in epileptic rats.     

Long-Term Adrenalectomy can Decrease or Increase Hippocampal Dentate Gyrus Volumes

Male and female Long-Evans adult rats were adrenalectomized and sacrificed 6 weeks later to determine whether dentate gyrus damage would differ in females and males. A subset of adrenalectomized rats of both sexes had significantly reduced dentate gyrus volumes compared to the same sex SHAM operated rats. The remainder of the male and female adrenalectomized rats which did not have clear dentate gyrus damage had significantly larger dentate gyrus volumes compared to the same sex SHAM rats. The dentate gyrus volumes of all adrenalectomized rats were significantly correlated with two indices of residual hormonal levels (Na⁺/K⁺ ratios and body weight gain 6 weeks after surgery), indicating that endogenous corticosterone levels may be a determining factor in the response of the dentate gyrus to adrenalectomy. These dentate gyrus volumetric changes could not be attributed to tissue shrinkage as there were no changes in CA3 volumes in any of the groups. These results suggest that long-term adrenalectomy can result in either increased or decreased dentate gyrus volumes and that the adrenal steroid levels of each individual adrenalectomized rat may be the factor determining the direction of the dentate gyrus volumetric response.     

Spontaneous limbic seizures after intrahippocampal infusion of brain-derived neurotrophic factor

The results of several studies have contributed to the hypothesis that BDNF promotes seizure activity, particularly in adult hippocampus. To test this hypothesis, BDNF, vehicle (phosphate-buffered saline, PBS), or albumin was infused directly into the hippocampus for 2 weeks using osmotic minipumps. Rats were examined behaviorally, electrophysiologically, and anatomically. An additional group was tested for sensitivity to the convulsant pilocarpine. Spontaneous behavioral seizures were observed in BDNF-infused rats (8/32; 25%) but not in controls (0/20; 0%). In a subset of six animals (three BDNF, three albumin), blind electrophysiological analysis of scalp recordings contralateral to the infused hippocampus demonstrated abnormalities in all BDNF rats; but not controls. Neuronal loss in BDNF-treated rats was not detected relative to PBS- or albumin-treated animals, but immunocytochemical markers showed a pattern of expression in BDNF-treated rats that was similar to rats with experimentally induced seizures. Thus, BDNF-infused rats had increased expression of NPY in hilar neurons of the dentate gyrus relative to control rats. NPY and BDNF expression was increased in the mossy fiber axons of dentate gyrus granule cells relative to controls. The increase in NPY and BDNF expression in BDNF-treated rats was bilateral and occurred throughout the septotemporal axis of the hippocampus. Mossy fiber sprouting occurred in five BDNF-treated rats but no controls. In another group of infused rats that was tested for seizure sensitivity to the convulsant pilocarpine, BDNF-infused rats had a shorter latency to status epilepticus than PBS-infused rats. In addition, the progression from normal behavior to severe seizures was faster in BDNF-treated rats. These data support the hypothesis that intrahippocampal BDNF infusion can facilitate, and potentially initiate, seizure activity in adult hippocampus.     

Increased levels of acidic calponin during dendritic spine plasticity after pilocarpine-induced seizures

We have previously shown that, in HEK 293 cells, overexpression of acidic calponin, an actin-binding protein, induces remodeling of actin filaments, leading to a change in cell morphology. In addition, this protein is found in dendritic spines of adult hippocampal neurons. We hypothesized that this protein plays a role in regulating actin-based filaments during dendritic spine plasticity. To assess this hypothesis, the pilocarpine model of temporal lobe epilepsy was selected because an important reorganization of the glutamatergic network, which includes an aberrant sprouting of granule cell axons, neo-synaptogenesis, and dendritic spine remodeling, is well established in the dentate gyrus. This reorganization begins after the initial period of status epilepticus after pilocarpine injection, during the silent period when animals display a normal behavior, and reaches a plateau at the chronic stage when the animals have developed spontaneous recurrent seizures. Our data show that the intensity of immunolabeling for acidic calponin was clearly increased in the inner one-third of the molecular layer of the dentate gyrus, the site of mossy fiber sprouting, and neo-synaptogenesis, at 1 and 2 weeks after pilocarpine injection (silent period) when the reorganization was taking place. In contrast, in chronic pilocarpine-treated animals, when the reorganization was established, the levels of labeling for acidic calponin in the inner molecular layer were similar to those observed in control rats. In addition, double immunostaining studies suggested that the increase in acidic calponin levels occurred within the dendritic spines. Altogether, these results are consistent with an involvement of acidic calponin in dendritic spine plasticity.