姜黄素以端粒酶为靶点治疗Aβ损伤的体外研究

目的　探讨端粒酶在姜黄素治疗β淀粉样蛋白（Aβ）损伤的神经保护效应中的作用。方法　用Aβ1-42（10　μg/mL）预处理SK-N-SH细胞建立损伤的细胞模型后,用姜黄素（10　μg/mL）干预治疗组,处理前后检测细胞存活率、细胞内氧化应激水平及hTERT的表达水平,并通过RNA干扰技术降低hTERT的表达,以此验证端粒酶在姜黄素的干预作用中所起的作用。结果　Aβ1-42预处理组的氧化应激水平及细胞毒性均有显著增高（P＜0.001）,hTERT的表达水平明显下降（P＜0.001）。姜黄素干预使SK-N-SH细胞免受Aβ1-42损伤（P＜0.001）并上调hTERT的表达水平（P＜0.001）。而当端粒酶活性被TERT的小分子干扰RNA抑制后,姜黄素的神经保护作用也随之消失（P＞0.05）。结论　姜黄素对抗Aβ毒性的神经保护作用有赖于端粒酶活性,端粒酶则可能是姜黄素治疗效应的靶点。     

补肾益智方治疗阿尔茨海默病斑马鱼模型的作用及机制研究

目的 通过阿尔茨海默病斑马鱼模型,探讨补肾益智方的作用机制。方法 选取6月龄斑马鱼,随机分成5组,分为空白对照组（n=12）、模型组（n=10）、阳性药组（n=10）、补肾益智方高剂量组（n=11）和低剂量组（n=12）。除空白对照组,其余各组均用AlCl₃·6H₂O配制成浓度为100 μg/L的溶液持续浸泡斑马鱼30 d,每天更换一半的染毒培养液。染毒结束后利用T迷宫实验剔除染毒失败的斑马鱼。造模结束后,分别给予阳性药组多奈哌齐20 μg/mL,高、低剂量组补肾益智方30、10 μg/mL浸泡14 d。给药结束后,通过T迷宫实验检测斑马鱼学习记忆能力;免疫组化染色观察神经元变化;qPCR检测相关基因的表达;Western blot检测相关蛋白的表达。结果 ①在T迷宫测试第4天,模型组潜伏时间为（198.00±45.78）s,补肾益智方低剂量组为（12.75±2.29）s,补肾益智方高剂量组为（7.27±0.90）s,补肾益智方治疗组斑马鱼的潜伏时间明显低于模型组,差异有统计学意义（P<0.05）;②补肾益智方治疗组斑马鱼的端脑神经元数量较模型组明显增多、排列变整齐,星型胶质细胞增多;③补肾益智方组斑马鱼脑ACHE活力显著降低（P<0.01）、ChAT活力显著增加（P<0.05）;④补肾益智方治疗组斑马鱼脑组织中appb、bace1表达显著降低（P<0.01）,sod、cat、nrf2基因表达显著增加（P<0.01）,keap1基因表达显著降低（P<0.01）;⑤补肾益智方治疗组斑马鱼脑组织蛋白表达情况与qPCR结果一致,APP、BACE1表达显著降低（P<0.01）,Nrf2表达显著增加（P<0.01）,Keap1表达显著降低（P<0.01）。结论 补肾益智方能有效改善AD斑马鱼的学习记忆能力,减少Aβ生成,减轻氧化应激。      

Arc/Arg3.1在糖尿病性脑病大鼠海马组织中的表达及其与认知功能改变的关系

目的：探讨糖尿病大鼠认知功能与海马Arc蛋白和β淀粉样蛋白（Aβ）表达的相关性,探讨突触可塑性在糖尿病性脑病（DE）发病机制中的作用。方法30只SPF级雄性8周龄大鼠随机分为对照组和糖尿病组,糖尿病组高脂饮食喂养4周后腹腔注射链脲佐菌素建立2型糖尿病大鼠模型,观察不同阶段动物的体质量、空腹血糖（FBG）、空腹血清胰岛素（FSI）,并计算胰岛素敏感指数（ISI）。实验末行水迷宫测试评估两组大鼠认知功能;酶联免疫吸附测定法、免疫组织化学法和蛋白质印迹法检测大鼠海马组织Aβ和Arc的表达。结果糖尿病组大鼠在目标象限的探索时间较对照组缩短（P＜0.01）,原平台穿越次数较对照组减少（P＜0.01）。糖尿病组Aβ表达较对照组升高（P＜0.01）,Arc/Arg3.1表达降低（P＜0.01）。结论糖尿病大鼠认知功能受损可能与Arc表达降低导致突触可塑性失衡加剧Aβ的沉积和神经元损伤有关。     

Aβ_(20-29)短肽阻断ApoE/Aβ结合并减少Aβ_(1-42)纤维化及其神经毒性的效应作用

目的:探讨β-淀粉样蛋白(Aβ)20-29(Aβ_(20-29))短肽在阻断载脂蛋白E(ApoE)4与Aβ_(1-42)相结合并减少Aβ_(1-42)纤维化及其神经毒性中的效应作用。方法:应用硫磺素-T(Th-T)荧光分析和透射电镜方法,观察Aβ_(20-29)短肽阻断ApoE与Aβ_(1-42)相结合及其防止Aβ_(1-42)纤维化的效应作用;应用培养的PC12细胞,观察Aβ_(20-29)短肽对ApoE4+Aβ_(1-42)神经毒性的效应作用。结果:荧光分析和透射电镜观察显示:Aβ_(20-29)短肽不能形成纤维性Aβ,ApoE4对Aβ_(1-42)纤维化具有显著促进作用,Aβ_(20-29)短肽能够显著减少ApoE4对Aβ_(1-42)纤维化的促进作用,且呈剂量依赖关系。应用培养的PC12细胞及MTT法测定细胞活性,表明Aβ_(20-29)短肽对PC12细胞无神经毒性作用,其能够显著减少ApoE4+Aβ_(1-42)的神经毒性作用。结论:Aβ_(20-29)短肽在体外能够有效抑制ApoE4与Aβ_(1-42)相结合,并显著减少Aβ_(1-42)纤维化及其神经毒性作用,提示Aβ_(20-29)短肽有可能成...     

Calcium-Sensing Receptors of Human Astrocyte-Neuron Teams: Amyloid-β-Driven Mediators and Therapeutic Targets of Alzheimer’s Disease

It is generally assumed that the neuropathology of sporadic (late-onset or nonfamilial) Alzheimer’s disease (AD) is driven by the overproduction and spreading of first Amyloid-β_x-42 (Aβ₄₂) and later hyperphosphorylated (hp)-Tau oligomeric “infectious seeds”. Hitherto, only neurons were held to make and spread both oligomer types; astrocytes would just remove debris. However, we have recently shown that exogenous fibrillar or soluble Aβ peptides specifically bind and activate the Ca²⁺-sensing receptors (CaSRs) of untransformed human cortical adult astrocytes and postnatal neurons cultured in vitro driving them to produce, accrue, and secrete surplus endogenous Aβ₄₂. While the Aβ-exposed neurons start dying, astrocytes survive and keep oversecreting Aβ₄₂, nitric oxide (NO), and vascular endothelial growth factor (VEGF)-A. Thus astrocytes help neurons’ demise. Moreover, we have found that a highly selective allosteric CaSR agonist (“calcimimetic”), NPS R-568, mimics the just mentioned neurotoxic actions triggered by Aβ●CaSR signaling. Contrariwise, and most important, NPS 2143, a highly selective allosteric CaSR antagonist (“calcilytic”), fully suppresses all the Aβ●CaSR signaling-driven noxious actions. Altogether our findings suggest that the progression of AD neuropathology is promoted by unceasingly repeating cycles of accruing exogenous Aβ₄₂ oligomers interacting with the CaSRs of swelling numbers of astrocyte-neuron teams thereby recruiting them to overrelease additional Aβ₄₂ oligomers, VEGF-A, and NO. Calcilytics would beneficially break such Aβ/CaSR-driven vicious cycles and hence halt or at least slow the otherwise unstoppable spreading of AD neuropathology     

Nasal mucosal inhalation of amyloid-beta peptide 3–10 defective adenovirus attenuates cytotoxicity induced by beta-amyloid(1–42)

Three-month-old Alzheimer's disease model transgenic mice were immunized with Aβ1–42, Plp-Adenovirus [Ad]-X-CMV-(Aβ3–10)10-CpG [AdCpG-(Aβ3–10)10] or AdCpG virus fluid via nasal mucosal inhalation, respectively. ELISA analysis of serum showed Aβ42 antibody titers were significantly increased in mice immunized with Aβ1–42 and AdCpG-(Aβ3–10)10. Concanavalin A and AdCpG-(Aβ3–10)10 stimulation significantly increased the number of proliferating spleen cells cultured from AdCpG(Aβ3–10)10 and Aβ42 groups compared with the control group. In the AdCpG(Aβ3–10)10 group, levels of interleukin(IL)-4 and IL-10 were increased, while those of IL-2 and interferon-γ were decreased. In the Aβ42 group, levels of IL-4, IL-10, IL-2 and interferon-γ were all increased. Experimental findings indicate that AdCpG-(Aβ3–10)10 vaccine can produce strong T helper 2(Th2) humoral immune responses in addition to the production of Aβ42 antibody. The cellular immunologic response was weak and avoided Aβ1–42-mediated cytotoxicity.     

Nicotine modifies in vivo and in vitro rat hippocampal amyloid precursor protein processing in young but not old rats

Previous studies have shown that administration of nicotine modifies the expression and secretion of amyloid precursor protein (APP) in various cell lines. The present study investigated the extent to which chronic subcutaneous nicotine administration influences APP levels and processing in cerebral cortex, striatum and hippocampus of young and old rat brains. The results showed that constant nicotine infusion (0.25 or 4.00 mg/kg/day) increased the levels of particulate APP (APPp) but not secreted APP (APPs) in the hippocampus of young rats in vivo. This response to nicotine was not observed in the striatum or cerebral cortex of young rats or in any of the brain regions examined in old animals. Subsequent in vitro analysis demonstrated that nicotine enhanced the release of APPs from hippocampal slice preparations and that this increase was attenuated by mecamylamine, a non-selective nicotinic acetylcholine receptor (nAChR) antagonist. The in vitro effect of nicotine on APPs was age-related, being only detected from hippocampal slices derived from the young but not the older animals. These results suggest that nicotine modulates APP expression and secretion in the hippocampus and that the responses observed to the drug are age-dependent being only detected in younger rats.     

白藜芦醇通过SIRT1激活ADAM10促进APPα代谢

目的：探讨白藜芦醇可否通过SIRT1激活解整合素金属蛋白酶10（ADAM10）促进APPα代谢抑制Aβ分泌。方法：选取过表达人瑞典突变淀粉样前体蛋白APP695sw的细胞模型,分别设立DMSO空白对照组、SIRT1激活剂白藜芦醇组和SIRT1抑制剂EX527组。给药后,ELISA法分别检测细胞培养上清中sAPPα和Aβ的含量,免疫印记Western Blot法检测细胞SIRT1和ADAM10的蛋白水平。结果：与对照组比较,白藜芦醇组细胞培养上清sAPPα的含量增高,Aβ含量下降,sAPPα/Aβ比值增大,细胞SIRT1和ADAM10蛋白水平增高;而抑制剂EX527组与对照相比,细胞培养上清sAPPα的含量降低,Aβ含量升高,sAPPα/Aβ比值减小,细胞SIRT1和ADAM10蛋白水平降低;抑制剂下调SIRT1后各项指标与激动剂组呈现相反的趋势（P<0.05）。结论：白藜芦醇可通过SIRT1激活ADAM10,促进APP进行α非淀粉样代谢途径,增强sAPPα分泌并抑制Aβ产生。     

β淀粉样蛋白对大鼠学习记忆功能及tau蛋白异常磷酸化的影响

为了探讨β淀粉样蛋白对大鼠学习记忆功能和tau蛋白异常磷酸化的影响,本文在海马注射Aβ25-35建立阿尔茨海黙病(AD)大鼠模型的基础上,通过行为学检测、HE染色、免疫组化和免疫蛋白印迹技术对动物的学习能力、组织的病理改变和tau(pS202)、tau(pT231)和tau-5的表达情况进行了分析。在行为学检测中,Aβ注射组大鼠在穿梭箱实验中的主动回避次数和被动回避次数减少,失败次数增多,而在Morris水迷宫测试中的逃避潜伏期和游泳距离延长。HE染色显示Aβ注射组大鼠海马CA1、CA3、齿状回的神经细胞数目减少;而免疫组化和免疫印迹结果显示注射组tau(pS202)阳性细胞明显增加,tau(pS202)、tau(pT231)和tau-5蛋白表达增加。以上结果提示海马内注射Aβ25-35可引起大鼠学习记忆功能下降,可能与神经细胞减少,tau蛋白异常磷酸化增多有关。     

Glucosamine and Its Analogues as Modulators of Amyloid-β Toxicity

In Alzheimer’s disease (AD), amyloid-β (Aβ) oligomers are considered key mediators of synaptic dysfunction and cognitive impairment. These unstable intermediate Aβ species can interfere with different cellular organelles, leading to neuronal cell death, through the formation of Ca²⁺-permeable membrane pores, impairment in the levels of acetylcholine neurotransmitters, increased insulin resistance, promotion of pro-inflammatory cascades, among others. Based on a series of evidences that indicate the key role of glycosaminoglycans (GAGs) in amyloid plaque formation, we evaluated the capacity of four monosaccharides, i.e., glucosamine (GlcN), N-acetyl glucosamine (GlcNAc), glucosamine-6-sulfate (GlcN6S), and glucosamine-6-phosphate (GlcN6P), to reduce the Aβ-mediated pathological hallmarks. The tested monosaccharides, in particular, GlcN6S and GlcN6P, were able to interact with Aβ aggregates, reducing neuronal cell death, Aβ-mediated damage to the cellular membrane, acetylcholinesterase activity, insulin resistance, and pro-inflammation levels.