远志总皂苷对AD模型大鼠海马Ng及pCaMKⅡα表达的影响

目的观察远志总皂苷(TEN)对阿尔茨海默病(AD)模型大鼠海马CA1区神经颗粒素(Ng)以及磷酸化的钙/钙调蛋白依赖性蛋白激酶Ⅱα亚基(pCaMKⅡα)表达的影响,探讨TEN防治AD的作用机制。方法将60只雄性Wistar大鼠随机分为对照组,模型组,TEN低剂量治疗组(12.5mg/ml)和TEN高剂量治疗组(37.5 mg/ml),每组15只,模型组予以腹腔注射D-半乳糖(D-gal)致衰并联合鹅膏覃氨酸(IBO)定向Meynert基底核损毁法建立AD大鼠模型,TEN低、高剂量治疗组则在造模的同时TEN灌胃治疗8w,对照组则用等体积的生理盐水代替D-gal和IBO。采用免疫组化方法来检测大鼠海马CA1区Ng及pCaMKⅡα的表达。结果模型组大鼠海马CA1区Ng及pCaMKⅡα平均吸光度值比对照组显著降低(P<0.01);TEN治疗组两组平均吸光度值均较模型组显著增高(P<0.01);且TEN高剂量治疗组(37.5 mg/ml)的平均吸光度值比TEN低剂量治疗组(12.5mg/ml)显著增高(P<0.01)。结论 TEN可显著升高AD模型大鼠海马CA1区Ng及pCaMKⅡα的表达,且具有剂量依赖性。     

单唾液酸神经节苷脂对帕金森病痴呆大鼠海马烟碱型乙酞胆碱受体α7亚基表达的影响

目的观察单唾液酸神经节苷脂(GM-1)对帕金森病痴呆(PDD)大鼠海马CA1区烟碱型乙酞胆碱受体(nAChRs)α7表达的影响。方法将雄性SD大鼠随机分为空白对照组、阳性对照组、模型组、GM-1低剂量组GM-1中剂量组、GM-1高剂量组,每组7只。PDD模型建立后,给予GM-1低剂量组(10 mg/kg)、中剂量组(20 mg/kg)及高剂量组(40 mg/kg)大鼠GM-1腹腔注射,1次/d,共8周;阳性对照组给予多奈哌齐0.5 mg/kg灌胃,1次/d,共8周。采用Morris水迷宫实验观察各实验组大鼠行为学指标,逆转录实时荧光定量PCR检测海马nAChRα7 mRNA表达,Western blotting定量检测海马nAChRα7蛋白表达,免疫荧光双标检测nAchRα7及神经元细胞(NeuN)水平。结果与空白对照组相比,阳性对照组、模型组、GM-1低剂量组、GM-1中剂量组、GM-1高剂量组逃避潜伏期均延长,模型组、GM-1低剂量组、GM-1中剂量组穿越平台次数明显减少(均P0.05)。与阳性对照组相比,模型组、GM-1低剂量组逃避潜伏期明显延长,模型组、GM-1低剂量组、GM-1中剂量组穿越平台次数明显减少(均P0.05)。GM-1低剂量组nAChRα7 mRNA表达显著高于空白对照组、阳性对照组、模型组、GM-1中剂量组和GM-1高剂量组(均P0.05)。与空白对照组及阳性对照组比较,模型组及GM-1中剂量组nAChRα7蛋白表达显著降低(均P0.05)。模型组nAChRα7蛋白表达显著低于GM-1低剂量组及GM-1高剂量组(均P0.05)。与空白对照组及阳性对照组比较,GM-1低剂量组、中剂量组nAchRα7显著降低,GM-1低剂量组、中剂量组及高剂量组NeuN显著降低(均P0.05)。与模型组比较,GM-1低剂量组nAchRα7、NeuN及GM-1中剂量组NeuN均显著降低(均P0.05)。GM-1高剂量组nAchRα7显著高于低剂量组(P0.05)。结论 GM-1可通过提高PDD大鼠海马CA1区nAChRα7的表达,改善认知功能。高剂量(40 mg/kg)GM-1的改善作用更明显。     

银杏内酯对拟AD模型大鼠海马烟碱型乙酰胆碱能受体表达的影响

目的探讨银杏内酯对拟Alzheimer disease(AD)大鼠学习记忆能力影响的可能机制。方法大鼠海马冈田酸(Okadaic acid,OA)微量注射,银杏内酯灌胃。Morris水迷宫实验检测大鼠学习记忆能力;Western blot- ting实验检测大鼠海马烟碱型乙酰胆碱能受体的表达;RT-PCR实验检测海马烟碱型乙酰胆碱能受体mRNA的表达。结果与对照组比较,模型组大鼠学习记忆能力明显下降(P<0.01),烟碱型乙酰胆碱能受体表达减少(P<0.05);与模型组相比,银杏内酯组大鼠学习记忆能力明显提高(P<0.01),烟碱型乙酰胆碱能受体表达增多(P<0.05)。各实验组大鼠烟碱型乙酰胆碱能受体α_3亚单位mRNA变化不明显;与对照组相比,模型组大鼠烟碱型乙酰胆碱能受体α_7亚单位mRNA明显增多(P<0.05);与模型组相比,银杏内酯组大鼠烟碱型乙酰胆碱能受体α_7亚单位mRNA减少明显(P<0.05)。结论银杏内酯提高拟AD大鼠的学习记忆能力可能与其在mRNA水平上影响烟碱型乙酰胆碱能受体,从而保护和改善其功能有关。     

远志总皂苷对阿尔茨海默病模型大鼠海马脑源性神经营养因子及酪氨酸蛋白激酶B表达的影响

目的观察远志总皂苷对阿尔茨海默病模型大鼠海马CA1区脑源性神经营养因子(BDNF)及其特异性受体酪氨酸蛋白激酶B(TrkB)表达的影响,探讨远志总皂苷对阿尔茨海默病的干预作用机制。方法雄性Wistar大鼠被随机分为生理盐水组(正常对照组)、阿尔茨海默病模型组(模型组),以及远志总皂苷低剂量(12.50 mg/ml)和高剂量(37.50 mg/ml)组;采用D-半乳糖致衰老联合鹅膏覃氨酸损毁基底前脑Meynert核法建立阿尔茨海默病大鼠模型,免疫组织化学染色检测大鼠海马CA1区BDNF及其受体TrkB表达水平。结果 BDNF和TrkB阳性物质呈棕黄色,主要表达于海马CA1区神经元胞膜。模型组大鼠海马CA1区BDNF及其受体TrkB表达水平为0.30±0.02和0.21±0.07,低于正常对照组的0.47±0.02和0.46±0.05(均P=0.000);与模型组相比,远志总皂苷低剂量组(0.35±0.05,0.32±0.07)和高剂量组(0.43±0.05,0.37±0.03)大鼠海马CA1区BDNF及其受体TrkB表达水平均显著升高(均P=0.000),但以高剂量组升高更为显著(均P=0.000)。结论远志总皂苷可以显著升高阿尔茨海默病模型大鼠海马CA1区BDNF及其受体TrkB表达水平,且具有剂量依赖性,这可能是其改善认知功能的机制之一。     

远志总皂苷增强鹅膏蕈氨酸诱导阿尔茨海默病大鼠的突触可塑性研究

目的观察远志提取物远志总皂苷(TEN)对D-半乳糖致衰鹅膏蕈氨酸(IBO)诱导阿尔茨海默病(AD)模型大鼠突触可塑性的影响,并探讨其可能机制。方法将雄性Wistar大鼠随机分为对照组、AD模型组及TEN高、低剂量组,每组8只。通过电生理实验测定各组大鼠长时程增强(LTP)的变化,用免疫组织化学方法测定海马CA1区神经元N-甲基-D-天冬氨酸受体2A亚基(NR2A)积分吸光度(IOD)值,间接观察其表达情况,并进行各组间比较。结果高频刺激(HFS)后1 min、30 min和60 min对照组LTP值为(203.17±7.468)%、(178.15±8.110)%和(164.17±7.026)%,AD模型组LTP值〔(168.63±10.809)%、(120.12±7.382)%和(102.88±2.357)%〕较对照组显著降低(均P<0.05)。TEN低剂量组LTP值为(177.67±14.038)%、(141.83±4.956)%和(121.17±4.792)%,TEN高剂量组LTP值为(192.00±2.449)%、(168.00±2.449)%和(141.75±9.251)%,均较AD模型组升高(P<0.05)。与对照组(30.12±3.45)比较,AD模型组IOD值(11.74±1.69)显著降低(P<0.05);与AD模型组比较,TEN组低剂量组、高剂量组IOD值(分别为20.78±2.66、25.86±2.98)均明显增高(P<0.05),且TEN高剂量组高于TEN低剂量组(P<0.05)。结论 TEN可能使海马CA1区LTP升高和NR2A表达增加,从而改善AD大鼠突触可塑性。     

白藜芦醇对AD大鼠学习记忆能力和海马P-tau表达的影响

目的探讨白藜芦醇(Resveratrol,Res)对阿尔茨海默病(Alzheimer’s disease,AD)模型大鼠学习记忆能力的影响及作用机制。方法 50只雄性SD大鼠随机分为假手术组、模型组和白藜芦醇高、中、低剂量组。采用Aβ双侧海马注射建立AD大鼠模型。水迷宫试验观察大鼠学习记忆能力的变化,HE染色观察大鼠海马组织形态结构变化,免疫组化SP法检测大鼠海马组织P-tau的表达。结果白藜芦醇可改善AD大鼠的学习记忆能力(P<0.01),减少海马神经元丢失,显著性降低海马P-tau蛋白的表达(P<0.01)。结论白藜芦醇能改善AD模型大鼠的学习记忆功能,其作用机制可能与有效降低P-tau蛋白有关。     

香港远志提取物对拟阿尔茨海默病大鼠学习记忆的影响及机制

目的探讨香港远志提取物对拟阿尔茨海默病(AD)模型大鼠学习记忆能力的影响及机制。方法SD大鼠随机分4组:假手术组、模型组及治疗A、B组。双侧海马CA1区注射Aβ25～35建立拟AD大鼠模型,治疗组按设定方式给药,假手术组、模型组给1%吐温溶液。给药28d,Morris水迷宫方法测定大鼠学习记忆能力,定量分析海马区乙酰胆碱酯酶(AChE)、超氧化物歧化酶(SOD)活力及丙二醛(MDA)含量。结果与假手术组比较,模型组大鼠的学习记忆能力、SOD活力显著降低,AchE活力、MDA含量显著增高(P<0.01)。与模型组比较,治疗组大鼠的学习记忆能力、SOD活力显著增高,AchE活力、MDA含量显著降低(P<0.05,或P<0.01)。结论香港远志乙酸乙酯提取物,可有效改善拟AD大鼠学习和记忆功能障碍,作用机制可能与降低AchE活力、调节胆碱能系统平衡;降低MDA含量、增强SOD活力,减少氧自由基产生,缓解氧化应激损伤有关。     

远志总皂苷对海马神经干细胞定向分化的作用及对Mash1表达的影响

目的 观察远志总皂苷(TEN)对体外培养海马神经干细胞向胆碱能神经元定向分化的作用,并进一步分析其对神经干细胞Mashl表达的影响. 方法 分离新生24h内昆明小鼠海马,悬浮培养神经干细胞,取第3代神经干细胞进行分化诱导.实验分4组:空白对照组、5mg/LTEN组、20mg/LTEN组、100mg/LTEN组.应用免疫组织化学法检测神经干细胞中神经元特异性烯醇化酶(NSE)及胆碱乙酰转移酶(ChAT)阳性细胞比率;采用RT-PCR半定量法检测各组神经干细胞Mashl的表达.结果 免疫组化结果显示:与对照组比较,TEN组神经干细胞向神经元及胆碱能神经元分化的比率明显升高,以20 mg/L剂量最明显,差异均有统计学意义(P<0.05);20 mg/L组Mashl的表达(0.9426±0.07286)亦明显高于对照组(0.7141±0.04016),差异具有统计学意义(P<0.05). 结论 TEN能够促进体外培养的海马神经干细胞向神经元及胆碱能神经元定向分化,能够促进神经干细胞中Mashl的表达.     

知母皂苷Ⅱ对老龄大鼠学习记忆行为及海马区神经元的影响

目的本实验研究知母皂苷BⅡ(Timosaponin B-Ⅱ,TB-Ⅱ)对自然衰老大鼠学习记忆能力的改善及海马区神经元的保护作用。方法 SD大鼠老年对照组(15只)、青年大鼠对照组(15只)、TB-II 1 mg/kg组(15只)、TB-II2 mg/kg组(15只)和TB-II 4 mg/kg组(15只)。Morris水迷宫实验测量动物逃避潜伏时间; Elisa法测定脑脊液IL-6和TNF-α含量; TUNEL法检测海马区凋亡神经元; HPLC法检测多巴胺、去甲肾上腺素和5-羟色胺含量。结果水迷宫实验显示老龄对照组逃避潜伏时间比青年对照组增加,差异有统计学意义(P 0. 05);给药组与老年对照组相比逃避潜伏时间明显缩短,差异有统计学意义(P 0. 05);给药组脑脊液IL-6和TNF-α浓度下降(P 0. 05);给药组海马区神经元凋亡减少(P 0. 05);给药组DA、NE和5-HT含量增加(P 0. 05)。结论知母皂苷BⅡ通过抑制大脑炎症介质生成和抑制海马区神经元凋亡,提高神经递质含量,明显改善自然衰老大鼠的学习和记忆能力。     

人α7nAChR的克隆、测序及可变剪接

目的:克隆人α7烟碱型乙酰胆碱受体(α7nAChR)亚单位全长cDNA,为研究α7在Alzheimer病中的作用机制奠定基础。方法:用PCR技术扩增人海马α7 cDNA,并进行克隆,酶切验证和测序。结果:成功扩增出人全长α7cDNA,测序证实与基因库中人α7(GI:1458119)序列完全一致,同时发现了两种α7的可变剪接形式。结论:人脑中可能存在3种不同的α7基因表达类型。     

Alpha 7 nicotinic receptor subunit is present on serotonin neurons projecting to hippocampus and septum

The serotonergic transmitter system regulates hippocampal activity through its raphe projection to hippocampus and medial septum/diagonal band of Broca complex (MS/DBB), and most likely also indirectly through its interaction with the cholinergic neurotransmitter system. Nicotine, e.g., enhances hippocampal serotonin release probably through presynaptic nicotinic receptors. We investigated the possible presence of the alpha 7-nicotinic subunit on serotonergic neurons projecting to hippocampus and MS/DBB. By retrograde neuronal tracing, hippocampal serotonergic neurons were identified and with double fluorescence immunostaining and Alexa-488 bound alpha-bungarotoxin the presence of active alpha 7 receptor on their soma was determined. Most of the retrogradely labeled serotonin neurons contained the alpha 7 subunit. A low degree of colocalization between alpha-bungarotoxin and serotonin-positive neurons suggest that the alpha 7 subunit may be transported anterogradely to the serotonergic axonal terminals.     

APP/PS1双转基因小鼠早期记忆功能障碍与胆碱能系统的关系研究

目的观察转APP/PS1基因阿尔茨海默病小鼠(APP/PS1小鼠)早期空间学习记忆功能及乙酰胆碱能系统的变化以及两者之间的相关性,探讨阿尔茨海默病早期学习记忆障碍的发病机制。方法应用Morris水迷宫法评定3月龄APP/PS1小鼠及相应野生型(WT)小鼠的空间学习记忆功能;采用免疫组织化学及组织化学染色方法检测脑组织中β-淀粉样蛋白(Aβ)斑块沉积情况;采用ELISA法检测脑组织中乙酰胆碱(ACh)含量以及胆碱乙酰转移酶(ChAT)和乙酰胆碱酯酶(AChE)活性,并探讨小鼠脑组织中ACh含量与其空间记忆能力、ChAT活性的相关性。结果水迷宫评定结果显示两组小鼠到达平台的潜伏期无统计学差异(P>0.05);APP/PS1小鼠在目标象限的游泳时间百分比〔(29.02±4.27)%〕和距离百分比〔(28.85±3.77)%〕较WT小鼠均下降(P<0.05)。APP/PS1小鼠脑组织中尚无Aβ斑块的沉积。APP/PS1小鼠脑组织中ACh含量〔(45.23±1.40)ng/g prot〕和ChAT活性〔(279.53±12.13)U/g组织湿重〕均较WT小鼠〔分别为(54.08±4.84)ng/gprot、(315.84±11.32)U/g组织湿重〕显著降低(P<0.05),两组小鼠脑组织中AChE活性无统计学差异(P>0.05)。小鼠脑组织中ACh含量与其空间记忆功能(目标象限航行时间百分比、目标象限航行路程百分比)呈正相关(r=0.861、r=0.874,P<0.05),ACh含量与ChAT活性呈正相关(r=0.926,P<0.05)。结论 APP/PS1小鼠空间记忆功能障碍、ACh含量减少和ChAT活性降低可发生于Aβ斑块沉积之前。脑组织中ACh含量减少和ChAT活性降低可能与APP/PS1小鼠记忆功能损害密切相关。     

6-hydroxydopamine lesion of rat nigrostriatal dopaminergic neurons differentially affects nicotinic acetylcholine receptor subunit mRNA expression

Nicotinic acetylcholine receptor (nAChR) subunit mRNA expression in the rat substantia nigra (SN) was assayed by semiquantitative RT-PCR following 6-hydroxydopamine (6-OHDA) lesion of nigrostriatal dopaminergic neurons. Six months after unilateral injection of 6-OHDA or saline into the SN, total RNA was isolated from ipsilateral and contralateral tissue samples. RT-PCR amplifications were performed with template titration using primers specific for sequences encoding

Mouse strain-specific nicotinic acetylcholine receptor expression by inhibitory interneurons and astrocytes in the dorsal hippocampus

The response by individuals to nicotine is likely to reflect the interaction of this compound with target nAChRs. However, resolving how different genetic backgrounds contribute to unique mouse strain-specific responses to this compound remains an important and unresolved issue. To examine this question in detail, expression of the nicotine acetylcholine receptor (nAChR) subunits alpha3, alpha4, alpha5, alpha7, beta2, and beta4 was measured in the dorsal hippocampus using immunohistochemistry in mouse strains or lines BALB/c, C3H/J, C57BL/6, CBA/J, DBA/2, Long Sleep (LS), Short Sleep (SS), and CF1. The nAChRs in all mice colocalized with glutamic acid decarboxylase (GAD)-positive interneurons that were subclassified into at least four groups based on nAChR subunit heterogeneity. A notable difference between mouse strains was the expression of nAChRs by astrocyte subpopulations in CA1 subregions whose numbers vary inversely with nAChR-immunostained neurons. This novel relationship also correlated with published parameters of strain sensitivity to nicotine. Attempts to identify the origin of this significant difference in nAChR expression among strains included comparison of the entire nAChRalpha4 gene sequence. Although multiple polymorphisms were identified, including two that changed nAChRalpha4 amino acid coding, none of these clearly correlate with strain-related differences in cell type-specific nAChR expression. These findings suggest that mouse strain-specific behavioral and physiological responses to nicotine are likely to be a reflection of a complex interplay between genetic factors that shape differences in expression and cellular architecture of this modulatory neurotransmitter system in the mammalian nervous system.     

Nicotinic acetylcholine receptor expression in the hippocampus of 27 mouse strains reveals novel inhibitory circuitry

Mouse strains are well-characterized to exhibit differences in their physiological and behavioral responses to nicotine. This report examines the expression of the high-affinity nicotine binding receptor subunit, neuronal nicotinic receptor subunit alpha 4 (nAChR alpha 4), in the dorsal hippocampus of 27 inbred mouse strains. Multiple differences among mouse strains in the cellular expression of nAChR alpha 4 between subregions of the hippocampal field are evident. Differences that we describe in the expression of nAChR alpha 4 suggest mouse strains of diverse genetic origin could exhibit significant variation in how this receptor contributes to modulating intrahippocampal circuitry. These findings define a genetic frame-work in which the strain-specific responses to nicotine include underlying contributions by the varied anatomical context in which nAChRs are expressed.     

Reduction of neuroinflammation alleviated mouse post bone fracture and stroke memory dysfunction

Tibia fracture (BF) enhances stroke injury and post-stroke memory dysfunction in mouse. Reduction of neuroinflammation by activation of α-7 nicotinic acetylcholine receptor (α-7 nAchR) reduced acute neuronal injury and sensorimotor dysfunction in mice with BF 1-day after stroke. We hypothesize that reduction of neuroinflammation by activation of α-7 nAchR improves long-term memory function of mice with BF 6-h before stroke. The mice were randomly assigned to saline, PHA-568487 (α-7 nAchR agonist) and methyllycaconitine (antagonist) treatment groups. The sensorimotor function was tested by adhesive removal and corner tests at 3 days, the memory function was tested by Y-maze test weekly for 8 weeks and novel objective recognition test at 8 weeks post-injuries. We found PHA-568487 treatment reduced, methyllycaconitine increased the number of CD68⁺ cells in the peri-infarct and hippocampal regions, neuronal injury in the infarct region, sensorimotor and long-term memory dysfunctions. PHA-568487 treatment also reduced, while methyllycaconitine treatment increased atrophy of hippocampal granule cell layer and white matter damage in the striatum. In addition, PHA-568487 treatment increased neuron proliferation in granule cell layer. Our data indicated that reduction of neuroinflammation through activation of α-7 nAchR decreased neuronal damage, sensorimotor and long-term memory dysfunction of mice with BF shortly before stroke.     

Dementia rating and nicotinic receptor expression in the prefrontal cortex in schizophrenia.

BACKGROUND: The etiology of dementia that occurs in patients with schizophrenia is not well understood. Nicotinic acetylcholine receptors have been implicated in cognitive function, and deficits in these receptors have been reported in schizophrenia. METHODS: The present study investigates possible associations of nicotinic receptor subunit expression in the dorsal lateral prefrontal cortex, an area known to be affected in schizophrenia, and dementia rating. RESULTS: alpha7 immunoreactivity was reduced by 20% to 28% and [(3)H]epibatidine binding was increased twofold in groups of patients with schizophrenia compared to normal control subjects matched for age, postmortem delay, and low levels of brain nicotine and cotinine. In contrast, no significant differences in alpha4, alpha3, or beta2 immunoreactivity or alpha7 messenger RNA expression were observed in schizophrenia patients compared with control subject values. Clinical dementia ratings in patients with schizophrenia were correlated with neither [(3)H]epibatidine binding nor nicotinic receptor subunit expression. CONCLUSIONS:These data indicate no relationship between the trend for reduced neocortical alpha7 subunit protein expression in schizophrenia and dementia. Further investigations are required to establish whether the reduction in alpha7 protein in the dorsal lateral prefrontal cortex is associated with clinical features other than dementia in schizophrenia.     

Explicit and implicit memory for music in healthy older adults and patients with mild Alzheimer’s disease

Introduction: Previous studies have found that music paired with lyrics at encoding may improve the memory performance of patients with mild Alzheimer’s disease (AD). To further explore memory for different types of musical stimuli, the current study examined both implicit and explicit memory for music with and without lyrics compared to spoken lyrics.

Method: In this mixed design, patients with probable mild AD (n = 15) and healthy older adults (n = 13) listened to auditory clips (song, instrumental, or spoken lyrics varied across three sessions) and then had their memory tested. Implicit memory was measured by the mere exposure effect. Explicit recognition memory was measured using a confidence-judgment receiver operating characteristic (ROC) paradigm, which allowed examination of the separate contributions made by familiarity and recollection.

Results: A significant implicit memory mere exposure effect was found for both groups in the instrumental and song but not the spoken condition. Both groups had the best explicit memory performance in the spoken condition, followed by song, and then instrumental conditions. Healthy older adults demonstrated more recollection than patients with AD in the song and spoken conditions, but both groups performed similarly in the instrumental condition. Patients with AD demonstrated more familiarity in the instrumental and song conditions than in the spoken condition.

Conclusions: The results have implications for memory interventions for patients with mild AD. The implicit memory findings suggest that patients with AD may still show a preference for information familiar to them. The explicit memory results support prior findings that patients with AD rely heavily on familiarity, but also suggest that there may be limitations on the benefits that music can provide to recognition memory performance.